FOUS30 KWBC 220759
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
359 AM EDT Tue Apr 22 2025

Day 1
Valid 12Z Tue Apr 22 2025 - 12Z Wed Apr 23 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE TEXAS PANHANDLE INTO WESTERN OKLAHOMA AND THE CENTRAL GULF
COAST...

...Texas and Oklahoma...

A west-east orientated warm front paired with a dryline over West
Texas will maintain an environment conducive for convection through
the night. An expeditious shortwave ejecting out of the Southern=20
Rockies will navigate over the Caprock aiding in focused mid-level=20
ascent within the confines of the boundary and relative instability
maximum situated near the front and points south and east.=20
Scattered convection will likely billow up off the eastern New
Mexico Caprock down into the Stockton Plateau leading to strong=20
mesoscale cores maintaining a prevalent convective footprint over=20
the Southern Plains.=20

Cell propagation will be east to southeast motions given the=20
850-250mb shear field, entering into fairly unstable environments=20
downstream that will be capable of holding the convective pattern=20
well into the evening. Precipitable water values will be 1+
deviations above season average which could yield hourly rates of
1-2 inches/hour. These types of setups tend to be tricky, but the=20
setup is historically one that favors isolated flash flood=20
concerns, especially within any urbanized areas across the Caprock=20
into the western Red River Basin. The inherited Marginal Risk
continued to highlight the region with an elevated threat for heavy
rainfall and flash flooding.

...Gulf Coast...

Convection will focus along the slow-moving frontal boundary over
the Lower Mississippi Valley, particularly across southern
Louisiana. Locally heavy rain with cores generally anchored to any
remnants of the front as it decays within the southern Parishes of
the state. Several CAMs indicated a heavy rainfall footprint from
the Texas/Louisiana border to the New Orleans metro area. The
flooding threat is modest at best due to the uncertain nature of=20
where the pulse convective regime will initiate, however the=20
individual totals being depicted via CAMs (5-8") and some global=20 deterministic (3-5") are very much capable of causing some flash=20
flood concerns across the area. A Marginal Risk remains in effect
for this portion of the state, with only minor reshaping from the
previous issuance.

Campbell/Kleebauer


Day 2 Valid 12Z Wed Apr 23 2025 - 12Z Thu Apr 24 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE CENTRAL AND SOUTHERN PLAINS...

Several shortwaves will be exiting the Rockies throughout the day=20
with several pockets of convective development sprawled across the=20
Central and Southern High Plains by the evening hours. While the
confidence continues to be lower on the maximum amounts there is
however higher confidence on the potential for scattered flash=20
flood prospects. Although the location of QPF maxima vary, there=20
is a general consensus of a widespread 1 to 2 inches from the Front
Range of Colorado/Wyoming/Nebraska south to the Red River Basin=20
near Texas to Kansas/Oklahoma. Some of these areas will have seen=20 significant rainfall prior to any additional impacts leading to=20
some localized lower FFG indices once the event occurs. The=20
inherited Marginal continued to mostly highlight areas across the=20
Plains that had an elevated threat for heavy rainfall and flash=20
flooding. The latest guidance and WPC QPF trended higher with QPF=20
over northeast Kansas, southern Nebraska, southwest Iowa and=20
northwest Missouri. As such, the Marginal Risk area was modified to
encompass that part of the region.

Campbell/Kleebauer


Day 3 Valid 12Z Thu Apr 24 2025 - 12Z Fri Apr 25 2025

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
KANSAS, OKLAHOMA, ARKANSAS AND MISSOURI...=20

The pattern will be favorable for multiple rounds of showers and
thunderstorms to move through the south-central U.S. With a moist,
unstable flow expected and shortwave energy passing through heavy=20
rainfall will likely develop across the region which may lead to=20
local flash flooding. Areal averages of 1 to 2 inches are forecast
with locally higher amounts possible. A Slight Risk for excessive=20
rainfall is in effect for a large portion of Kansas, northern=20
Oklahoma, far northwest Arkansas and western Missouri. A Marginal=20
Risk area spans from northern Texas to southern Nebraska and=20
extreme southwest Iowa.

Campbell

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!7DX7Yqu-nxctWKk8_gPbTEg1uajmJjv2fQOHhpt0UiYr= itAqKK-cnJ6QTefXxirrFMK0qK1QqbZ59B_VujwFvKjsX_k$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!7DX7Yqu-nxctWKk8_gPbTEg1uajmJjv2fQOHhpt0UiYr= itAqKK-cnJ6QTefXxirrFMK0qK1QqbZ59B_VujwFPv2DpF8$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!7DX7Yqu-nxctWKk8_gPbTEg1uajmJjv2fQOHhpt0UiYr= itAqKK-cnJ6QTefXxirrFMK0qK1QqbZ59B_VujwFkI7fY6E$=20

=3D =3D =3D
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FOUS30 KWBC 221208
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
808 AM EDT Tue Apr 22 2025

Day 1
Valid 12Z Tue Apr 22 2025 - 12Z Wed Apr 23 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE TEXAS PANHANDLE INTO WESTERN OKLAHOMA AND THE CENTRAL GULF
COAST INTO THE SOUTHEAST...

12z Update: The Marginal risk was expanded over the Southeast and
now stretches from LA northeastward into portions of MS/AL and the
southern Appalachians. Convection near a stalled boundary will be
capable of producing heavy rainfall rates today across this=20
corridor. See MPD 147 for more info on the near term possible=20
flash flood risk across portions of northern MS and AL.

Chenard

...Previous Discussion...

...Texas and Oklahoma...

A west-east orientated warm front paired with a dryline over West
Texas will maintain an environment conducive for convection through
the night. An expeditious shortwave ejecting out of the Southern
Rockies will navigate over the Caprock aiding in focused mid-level
ascent within the confines of the boundary and relative instability
maximum situated near the front and points south and east.
Scattered convection will likely billow up off the eastern New
Mexico Caprock down into the Stockton Plateau leading to strong
mesoscale cores maintaining a prevalent convective footprint over
the Southern Plains.

Cell propagation will be east to southeast motions given the
850-250mb shear field, entering into fairly unstable environments
downstream that will be capable of holding the convective pattern
well into the evening. Precipitable water values will be 1+
deviations above season average which could yield hourly rates of
1-2 inches/hour. These types of setups tend to be tricky, but the
setup is historically one that favors isolated flash flood
concerns, especially within any urbanized areas across the Caprock
into the western Red River Basin. The inherited Marginal Risk
continued to highlight the region with an elevated threat for heavy
rainfall and flash flooding.

...Gulf Coast...

Convection will focus along the slow-moving frontal boundary over
the Lower Mississippi Valley, particularly across southern
Louisiana. Locally heavy rain with cores generally anchored to any
remnants of the front as it decays within the southern Parishes of
the state. Several CAMs indicated a heavy rainfall footprint from
the Texas/Louisiana border to the New Orleans metro area. The
flooding threat is modest at best due to the uncertain nature of
where the pulse convective regime will initiate, however the
individual totals being depicted via CAMs (5-8") and some global
deterministic (3-5") are very much capable of causing some flash
flood concerns across the area. A Marginal Risk remains in effect
for this portion of the state, with only minor reshaping from the
previous issuance.

Campbell/Kleebauer


Day 2
Valid 12Z Thu Apr 24 2025 - 12Z Fri Apr 25 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE CENTRAL AND SOUTHERN PLAINS...

Several shortwaves will be exiting the Rockies throughout the day
with several pockets of convective development sprawled across the
Central and Southern High Plains by the evening hours. While the
confidence continues to be lower on the maximum amounts there is
however higher confidence on the potential for scattered flash
flood prospects. Although the location of QPF maxima vary, there
is a general consensus of a widespread 1 to 2 inches from the Front
Range of Colorado/Wyoming/Nebraska south to the Red River Basin
near Texas to Kansas/Oklahoma. Some of these areas will have seen
significant rainfall prior to any additional impacts leading to
some localized lower FFG indices once the event occurs. The
inherited Marginal continued to mostly highlight areas across the
Plains that had an elevated threat for heavy rainfall and flash
flooding. The latest guidance and WPC QPF trended higher with QPF
over northeast Kansas, southern Nebraska, southwest Iowa and
northwest Missouri. As such, the Marginal Risk area was modified to
encompass that part of the region.

Campbell/Kleebauer


Day 3=20
Valid 12Z Thu Apr 24 2025 - 12Z Fri Apr 25 2025

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
KANSAS, OKLAHOMA, ARKANSAS AND MISSOURI...

The pattern will be favorable for multiple rounds of showers and
thunderstorms to move through the south-central U.S. With a moist,
unstable flow expected and shortwave energy passing through heavy
rainfall will likely develop across the region which may lead to
local flash flooding. Areal averages of 1 to 2 inches are forecast
with locally higher amounts possible. A Slight Risk for excessive
rainfall is in effect for a large portion of Kansas, northern
Oklahoma, far northwest Arkansas and western Missouri. A Marginal
Risk area spans from northern Texas to southern Nebraska and
extreme southwest Iowa.

Campbell

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!5A5u2BevogXhh2MoEuH_wzGHfeB-HbojUeM2tPjyEc6j= PjFTEQzcw1Z3rcs7K9oXm50MD-CyY-02uH2ep_FLCLS4764$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!5A5u2BevogXhh2MoEuH_wzGHfeB-HbojUeM2tPjyEc6j= PjFTEQzcw1Z3rcs7K9oXm50MD-CyY-02uH2ep_FLLr9oiP0$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!5A5u2BevogXhh2MoEuH_wzGHfeB-HbojUeM2tPjyEc6j= PjFTEQzcw1Z3rcs7K9oXm50MD-CyY-02uH2ep_FLeCDASrA$=20

=3D =3D =3D
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FOUS30 KWBC 221500
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1100 AM EDT Tue Apr 22 2025

Day 1
Valid 16Z Tue Apr 22 2025 - 12Z Wed Apr 23 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTH...

The inherited Marginal Risk areas across the Panhandles of Texas
and Oklahoma as well as the newly expanded Marginal from the lower
Mississippi Valley to the southern Appalachians were combined to
cover much of Texas with this update. There remain 2 distinct
features forcing the thunderstorms, a stationary boundary draped
from the Lower Mississippi Valley to the southern Appalachians, and
a progressive dry line that will spawn new thunderstorms across
western and central Texas later this afternoon though tonight.
While the area in between...namely east Texas, has a notably lower
chance of flash flooding, enough of the guidance suggests there to
be enough overlap late tonight between earlier convection and those
areas harder hit over the past day or so to justify the combining
of the inherited Marginal Risk areas.

This summer-like pattern of convection is much less predictable
than the colder season larger precipitation shields of the past
several months. It's therefore becoming the season where larger
swaths of the country are broadly under a localized threat for
flash flooding as thunderstorm complexes interact with one another
in largely unpredictable ways, with enhanced impacts should those
interactions occur over urban areas. The combined Marginals thus
highlight these larger features for the potential for training
convection once cell interactions are taken into account. Given the
increasing amounts of atmospheric Gulf moisture advecting into
these features, resultant convection will have the potential to
cause localized rainfall rates of up to 2 inches per hour.
Localized flash flooding is most likely to occur where these rates
coincide with lower FFGs from recent heavy rainfall.

Wegman


Day 2
Valid 12Z Wed Apr 23 2025 - 12Z Thu Apr 24 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE CENTRAL AND SOUTHERN PLAINS...

Several shortwaves will be exiting the Rockies throughout the day
with several pockets of convective development sprawled across the
Central and Southern High Plains by the evening hours. While the
confidence continues to be lower on the maximum amounts there is
however higher confidence on the potential for scattered flash
flood prospects. Although the location of QPF maxima vary, there
is a general consensus of a widespread 1 to 2 inches from the Front
Range of Colorado/Wyoming/Nebraska south to the Red River Basin
near Texas to Kansas/Oklahoma. Some of these areas will have seen
significant rainfall prior to any additional impacts leading to
some localized lower FFG indices once the event occurs. The
inherited Marginal continued to mostly highlight areas across the
Plains that had an elevated threat for heavy rainfall and flash
flooding. The latest guidance and WPC QPF trended higher with QPF
over northeast Kansas, southern Nebraska, southwest Iowa and
northwest Missouri. As such, the Marginal Risk area was modified to
encompass that part of the region.

Campbell/Kleebauer


Day 3
Valid 12Z Thu Apr 24 2025 - 12Z Fri Apr 25 2025

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
KANSAS, OKLAHOMA, ARKANSAS AND MISSOURI...

The pattern will be favorable for multiple rounds of showers and
thunderstorms to move through the south-central U.S. With a moist,
unstable flow expected and shortwave energy passing through heavy
rainfall will likely develop across the region which may lead to
local flash flooding. Areal averages of 1 to 2 inches are forecast
with locally higher amounts possible. A Slight Risk for excessive
rainfall is in effect for a large portion of Kansas, northern
Oklahoma, far northwest Arkansas and western Missouri. A Marginal
Risk area spans from northern Texas to southern Nebraska and
extreme southwest Iowa.

Campbell

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!6Z4X0QM-cOMdluYqDWyBTngntLAWivQKkz0R_yGU1w1p= Tqd2oXhVSgwQ0ogq9arCggHsHgXNwUfloRW_-zXClAzcyTw$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!6Z4X0QM-cOMdluYqDWyBTngntLAWivQKkz0R_yGU1w1p= Tqd2oXhVSgwQ0ogq9arCggHsHgXNwUfloRW_-zXCAA1gQ70$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!6Z4X0QM-cOMdluYqDWyBTngntLAWivQKkz0R_yGU1w1p= Tqd2oXhVSgwQ0ogq9arCggHsHgXNwUfloRW_-zXC4V9_vGo$=20

=3D =3D =3D
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FOUS30 KWBC 221900
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
300 PM EDT Tue Apr 22 2025

Day 1
Valid 16Z Tue Apr 22 2025 - 12Z Wed Apr 23 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTH...

...16Z Update...

The inherited Marginal Risk areas across the Panhandles of Texas
and Oklahoma as well as the newly expanded Marginal from the lower
Mississippi Valley to the southern Appalachians were combined to
cover much of Texas with this update. There remain 2 distinct
features forcing the thunderstorms, a stationary boundary draped
from the Lower Mississippi Valley to the southern Appalachians, and
a progressive dry line that will spawn new thunderstorms across
western and central Texas later this afternoon though tonight.
While the area in between...namely east Texas, has a notably lower
chance of flash flooding, enough of the guidance suggests there to
be enough overlap late tonight between earlier convection and those
areas harder hit over the past day or so to justify the combining
of the inherited Marginal Risk areas.

This summer-like pattern of convection is much less predictable
than the colder season larger precipitation shields of the past
several months. It's therefore becoming the season where larger
swaths of the country are broadly under a localized threat for
flash flooding as thunderstorm complexes interact with one another
in largely unpredictable ways, with enhanced impacts should those
interactions occur over urban areas. The combined Marginals thus
highlight these larger features for the potential for training
convection once cell interactions are taken into account. Given the
increasing amounts of atmospheric Gulf moisture advecting into
these features, resultant convection will have the potential to
cause localized rainfall rates of up to 2 inches per hour.
Localized flash flooding is most likely to occur where these rates
coincide with lower FFGs from recent heavy rainfall.

Wegman


Day 2
Valid 12Z Wed Apr 23 2025 - 12Z Thu Apr 24 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE PLAINS AND THE SOUTHEAST...

...19Z Update...

The inherited Marginal Risk was greatly expanded towards the south
and east with this update. The area now includes much of northern
and eastern Texas, and the northern portions of the Southeast
through into the Carolinas. This eastward expansion has largely to
do with the increasing Gulf moisture streaming north into the
Southeast with a very persistent souther LLJ, and a similarly
persistent stationary front that will remain draped across the
Southeast. The clash of this warm and humid air with the front will
cause a renewed round of showers and thunderstorms from east Texas
through to the Carolinas. While the large-scale pattern favors more
slow-moving training thunderstorms, there is significant
disagreement in the guidance as to what form those storms will
take, whether groups of cells and MCSs interact, and ultimately
where these interactions may occur. Since the front remains in
place, the storms are likely to move over many of the same areas
being impacted by ongoing showers and storms this afternoon, which
locally increases the flash flooding risk.

There is somewhat better agreement in the guidance that the=20
wettest areas will likely focusing into southern Nebraska and=20
northern Kansas on Wednesday. This too will be the result of an MCS
or clusters of thunderstorms developing and training multiple times
over the same areas. The Marginal remains in place as the consensus
of heaviest rains on the order of 1-2 inches (locally higher, of
course) is in a portion of Kansas and Nebraska that has largely
missed out on recent heavy rainfall, and the antecedent dry
conditions should help to offset and delay the greatest impacts
from any heavy rain.

The area of the Marginal of least concern appears to be over
Oklahoma, which while seeing some scattered shower and thunderstorm
activity, should be between the MCSs/areas of more organized and
persistent convection. However, due to heavy rainfall, lower FFGs
over much of the state lower the threshold needed to achieve flash
flooding, so the Marginal is largely unchanged there.

Wegman

...Previous Discussion...

Several shortwaves will be exiting the Rockies throughout the day
with several pockets of convective development sprawled across the
Central and Southern High Plains by the evening hours. While the
confidence continues to be lower on the maximum amounts there is
however higher confidence on the potential for scattered flash
flood prospects. Although the location of QPF maxima vary, there
is a general consensus of a widespread 1 to 2 inches from the Front
Range of Colorado/Wyoming/Nebraska south to the Red River Basin
near Texas to Kansas/Oklahoma. Some of these areas will have seen
significant rainfall prior to any additional impacts leading to
some localized lower FFG indices once the event occurs. The
inherited Marginal continued to mostly highlight areas across the
Plains that had an elevated threat for heavy rainfall and flash
flooding. The latest guidance and WPC QPF trended higher with QPF
over northeast Kansas, southern Nebraska, southwest Iowa and
northwest Missouri. As such, the Marginal Risk area was modified to
encompass that part of the region.

Campbell/Kleebauer


Day 3
Valid 12Z Thu Apr 24 2025 - 12Z Fri Apr 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF=20
KANSAS, OKLAHOMA, ARKANSAS AND MISSOURI...

...19Z Update...

Multiple clusters of thunderstorms will likely be ongoing in
different portions of the ERO risk areas at the start of the Day
3/Thursday time period. These MCS's will likely weaken and
dissipate through the late morning, as MCS's typically do. However,
with peak heating and the increased instability associated
therewith, renewed rounds of showers and thunderstorms will
redevelop. Since this is likely to occur over many of the same
areas hit with heavy rain both now and on D2/Wednesday, this will
once again renew the potential for localized flash flooding over
portions of the Southeast.=20

For the Slight Risk area, these showers and storms will likely
redevelop in areas particularly forecast to be hard hit with heavy
rain from the D2/Wednesday time period, along with the potential
for a new MCS to form Thursday night, resulting in more widespread
heavy rainfall. Thus, the Slight Risk was maintained where it was
already issued, and expanded south and east with this update into
more of Missouri, Arkansas, and Oklahoma. This expansion is largely
a function of much of this area being hit with heavy rain a few
days ago, and the rivers will not have fully drained, and the
typical evolution of MCSs in the guidance to trend south with time.=20

For all areas, the LLJ out of the Gulf will tap into some of the
deepest moisture yet as compared with the previous two days. This
will support both heavier rainfall with the strongest storms, and
greater coverage of showers and storms in general. Due to inherent uncertainties with how the MCSs/storms will evolve and interact
with each other, at this point it appears unlikely additional
upgrades to a Moderate will be needed, as errors in thunderstorm
placement and coverage are high by the Day 3 period. However,
should the forecast remain wet and rainfall from the current D1 and
D2 periods outperform, then a targeted Moderate Risk cannot be
completely ruled out by the time more of the CAMs have a chance to
analyze the weather pattern.

Wegman

...Previous Discussion...

The pattern will be favorable for multiple rounds of showers and
thunderstorms to move through the south-central U.S. With a moist,
unstable flow expected and shortwave energy passing through heavy
rainfall will likely develop across the region which may lead to
local flash flooding. Areal averages of 1 to 2 inches are forecast
with locally higher amounts possible. A Slight Risk for excessive
rainfall is in effect for a large portion of Kansas, northern
Oklahoma, far northwest Arkansas and western Missouri. A Marginal
Risk area spans from northern Texas to southern Nebraska and
extreme southwest Iowa.

Campbell

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!4gZ_IzidjML7wJCYMcv7rX97az_4mWQvpaiNK6XcCT0d= w2kj-K3EZ1bKnf70tAIC0GszZrmSySxiEW6ptFZHY4CHkI4$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!4gZ_IzidjML7wJCYMcv7rX97az_4mWQvpaiNK6XcCT0d= w2kj-K3EZ1bKnf70tAIC0GszZrmSySxiEW6ptFZH6qQ5NdY$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!4gZ_IzidjML7wJCYMcv7rX97az_4mWQvpaiNK6XcCT0d= w2kj-K3EZ1bKnf70tAIC0GszZrmSySxiEW6ptFZHdsVA8ak$=20

=3D =3D =3D
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FOUS30 KWBC 230050
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
850 PM EDT Tue Apr 22 2025

Day 1
Valid 01Z Wed Apr 23 2025 - 12Z Wed Apr 23 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTH...

...01Z Excessive Rainfall Discussion...

Returned to having two Marginal Risk areas with the loss of daytime heating/instability...namely along/near the Gulf coast and Lower
Mississippi Valley as well as across parts of West Texas into the
Southern Plains. The convection that persists into the late
evening/early morning hours from Louisiana and southeast Texas
should continue to focus along and south of a quasi-stationary
boundary stretching from the Lower Mississippi Valley into the
southern Appalachians. From parts of West Texas eastward into=20
Oklahoma and should be developing along and east of a progressive=20
dry-line and then expanding eastward as the low level jet develops=20
later tonight. As mentioned previously...the some of the areas=20
where convection develops later tonight have notably lower flash=20
flood guidance but the signal for heavy rainfall amounts/rates is=20
less not as stong.

Bann

Day 2
Valid 12Z Wed Apr 23 2025 - 12Z Thu Apr 24 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE PLAINS AND THE SOUTHEAST...

...19Z Update...

The inherited Marginal Risk was greatly expanded towards the south
and east with this update. The area now includes much of northern
and eastern Texas, and the northern portions of the Southeast
through into the Carolinas. This eastward expansion has largely to
do with the increasing Gulf moisture streaming north into the
Southeast with a very persistent souther LLJ, and a similarly
persistent stationary front that will remain draped across the
Southeast. The clash of this warm and humid air with the front will
cause a renewed round of showers and thunderstorms from east Texas
through to the Carolinas. While the large-scale pattern favors more
slow-moving training thunderstorms, there is significant
disagreement in the guidance as to what form those storms will
take, whether groups of cells and MCSs interact, and ultimately
where these interactions may occur. Since the front remains in
place, the storms are likely to move over many of the same areas
being impacted by ongoing showers and storms this afternoon, which
locally increases the flash flooding risk.

There is somewhat better agreement in the guidance that the
wettest areas will likely focusing into southern Nebraska and
northern Kansas on Wednesday. This too will be the result of an MCS
or clusters of thunderstorms developing and training multiple times
over the same areas. The Marginal remains in place as the consensus
of heaviest rains on the order of 1-2 inches (locally higher, of
course) is in a portion of Kansas and Nebraska that has largely
missed out on recent heavy rainfall, and the antecedent dry
conditions should help to offset and delay the greatest impacts
from any heavy rain.

The area of the Marginal of least concern appears to be over
Oklahoma, which while seeing some scattered shower and thunderstorm
activity, should be between the MCSs/areas of more organized and
persistent convection. However, due to heavy rainfall, lower FFGs
over much of the state lower the threshold needed to achieve flash
flooding, so the Marginal is largely unchanged there.

Wegman

...Previous Discussion...

Several shortwaves will be exiting the Rockies throughout the day
with several pockets of convective development sprawled across the
Central and Southern High Plains by the evening hours. While the
confidence continues to be lower on the maximum amounts there is
however higher confidence on the potential for scattered flash
flood prospects. Although the location of QPF maxima vary, there
is a general consensus of a widespread 1 to 2 inches from the Front
Range of Colorado/Wyoming/Nebraska south to the Red River Basin
near Texas to Kansas/Oklahoma. Some of these areas will have seen
significant rainfall prior to any additional impacts leading to
some localized lower FFG indices once the event occurs. The
inherited Marginal continued to mostly highlight areas across the
Plains that had an elevated threat for heavy rainfall and flash
flooding. The latest guidance and WPC QPF trended higher with QPF
over northeast Kansas, southern Nebraska, southwest Iowa and
northwest Missouri. As such, the Marginal Risk area was modified to
encompass that part of the region.

Campbell/Kleebauer


Day 3
Valid 12Z Thu Apr 24 2025 - 12Z Fri Apr 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
KANSAS, OKLAHOMA, ARKANSAS AND MISSOURI...

...19Z Update...

Multiple clusters of thunderstorms will likely be ongoing in
different portions of the ERO risk areas at the start of the Day
3/Thursday time period. These MCS's will likely weaken and
dissipate through the late morning, as MCS's typically do. However,
with peak heating and the increased instability associated
therewith, renewed rounds of showers and thunderstorms will
redevelop. Since this is likely to occur over many of the same
areas hit with heavy rain both now and on D2/Wednesday, this will
once again renew the potential for localized flash flooding over
portions of the Southeast.

For the Slight Risk area, these showers and storms will likely
redevelop in areas particularly forecast to be hard hit with heavy
rain from the D2/Wednesday time period, along with the potential
for a new MCS to form Thursday night, resulting in more widespread
heavy rainfall. Thus, the Slight Risk was maintained where it was
already issued, and expanded south and east with this update into
more of Missouri, Arkansas, and Oklahoma. This expansion is largely
a function of much of this area being hit with heavy rain a few
days ago, and the rivers will not have fully drained, and the
typical evolution of MCSs in the guidance to trend south with time.

For all areas, the LLJ out of the Gulf will tap into some of the
deepest moisture yet as compared with the previous two days. This
will support both heavier rainfall with the strongest storms, and
greater coverage of showers and storms in general. Due to inherent uncertainties with how the MCSs/storms will evolve and interact
with each other, at this point it appears unlikely additional
upgrades to a Moderate will be needed, as errors in thunderstorm
placement and coverage are high by the Day 3 period. However,
should the forecast remain wet and rainfall from the current D1 and
D2 periods outperform, then a targeted Moderate Risk cannot be
completely ruled out by the time more of the CAMs have a chance to
analyze the weather pattern.

Wegman

...Previous Discussion...

The pattern will be favorable for multiple rounds of showers and
thunderstorms to move through the south-central U.S. With a moist,
unstable flow expected and shortwave energy passing through heavy
rainfall will likely develop across the region which may lead to
local flash flooding. Areal averages of 1 to 2 inches are forecast
with locally higher amounts possible. A Slight Risk for excessive
rainfall is in effect for a large portion of Kansas, northern
Oklahoma, far northwest Arkansas and western Missouri. A Marginal
Risk area spans from northern Texas to southern Nebraska and
extreme southwest Iowa.

Campbell

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!_Cz4O4QnkZQhrrzG8eEOVWKZvuirFIGiiFbNF-vgT1wy= mnu4VrAKbsbpugHjCnEfFmiLh_kx4S7bpUfihdalLUAP8Ow$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!_Cz4O4QnkZQhrrzG8eEOVWKZvuirFIGiiFbNF-vgT1wy= mnu4VrAKbsbpugHjCnEfFmiLh_kx4S7bpUfihdalBYFTEus$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!_Cz4O4QnkZQhrrzG8eEOVWKZvuirFIGiiFbNF-vgT1wy= mnu4VrAKbsbpugHjCnEfFmiLh_kx4S7bpUfihdalek9bs8w$=20

=3D =3D =3D
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FOUS30 KWBC 230759
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
359 AM EDT Wed Apr 23 2025

Day 1
Valid 12Z Wed Apr 23 2025 - 12Z Thu Apr 24 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE PLAINS AND THE SOUTHEAST...

Persistent Gulf moisture advecting northward through the Gulf=20
states over a stalled frontal boundary draped across the Southeast
will continue to produce scattered to widespread convection capable
of producing heavy rainfall. Rounds of showers and thunderstorms
will fire up along the the boundary from Texas to the Carolinas
with some training and backbuilding expected. Given there will be
very little movement of the front the storms are likely to track over
many of the same areas being impacted by ongoing showers and=20
storms of late, which locally increases the flash flooding risk. A
convective complex tracking east across the Hill Country during=20
the very early hours of Wednesday is spreading 0.5 to 1 inch/hour
rain rates along its path which may lead to isolated urban flash
flooding. Refer to WPC mesoscale precipitation discussion #160 for
more details.=20

The latest guidance has better confidence that the wettest areas=20
will likely focus over southern Nebraska and northern Kansas. This
too will be the result of an MCS or clusters of thunderstorms=20
developing and training multiple times over the same areas. The=20
Marginal remains in place as the consensus of heaviest rains on the
order of 1-2 inches (locally higher, of course) is in a portion of
Kansas and Nebraska that has largely missed out on recent heavy=20
rainfall, and the antecedent dry conditions should help to offset=20
and delay the greatest impacts from any heavy rain.

The area of the Marginal of least concern appears to be over
Oklahoma, which while seeing some scattered shower and thunderstorm
activity, should be between the MCSs/areas of more organized and
persistent convection. However, due to heavy rainfall, lower FFGs
over much of the state lower the threshold needed to achieve flash
flooding, so the Marginal is largely unchanged there.

Campbell/Wegman


Day 2
Valid 12Z Thu Apr 24 2025 - 12Z Fri Apr 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
KANSAS, OKLAHOMA, ARKANSAS AND MISSOURI...

Multiple clusters of thunderstorms will likely be ongoing in
different portions of the ERO risk areas at the start of the Day
3/Thursday time period. These MCS's will likely weaken and
dissipate through the late morning, as MCS's typically do. However,
with peak heating and the increased instability there will be
renewed rounds of showers and thunderstorms. Since this is likely=20
to occur over many of the same areas hit with recent heavy rain=20
this will once again renew the potential for localized flash=20
flooding over portions of the Southeast. Much of the guidance has
areal averages of 1 to 2 inches with higher maximums possible
falling over much of the same footprint in the day(s) prior. The
potential for a new MCS to form Thursday night will keep the=20
threat for flash flooding elevated. The inherited Slight Risk
remained largely untouched as it continued to reflect the areas
with the greater threat for flash flooding.

In similar fashion as Day 1, the low level jet will keep a steady
influx of Gulf moisture over the stalled boundary which will
maintain support for heavier rainfall with the strongest storms,=20
and greater coverage of showers and storms in general. A Marginal
Risk covers the northern Gulf states and Southeast.

Campbell


Day 3
Valid 12Z Fri Apr 25 2025 - 12Z Sat Apr 26 2025

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL MID-MISSISSIPPI VALLEY/Tennessee VALLEY TO PORTIONS OF THE NORTHEAST...

Recent and ongoing rainfall over some portions of this broad=20
region will make some areas susceptible to additional rains. During
this period a surface low pressure system and its attendant front
will likely track from the Mississippi Valley toward the Great
Lakes region and interior Northeast. This system will usher in
showers and thunderstorms to areas with increased soil saturation
and lower FFGs. The broad Marginal Risk was maintained from the
Tennessee Valley to the New Hampshire/Maine border given the
increasing signal for heavier and more widespread QPF.

Campbell

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!-uTuhbeontz0R9D_LhWWrxX7H17lTHzLUhMFm9wPn9JA= b0waoMA_bNiB4NlMRGlD-sSpOlRLUxYesAhS0M4V3w0ZjaE$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!-uTuhbeontz0R9D_LhWWrxX7H17lTHzLUhMFm9wPn9JA= b0waoMA_bNiB4NlMRGlD-sSpOlRLUxYesAhS0M4VJ5MSx2g$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!-uTuhbeontz0R9D_LhWWrxX7H17lTHzLUhMFm9wPn9JA= b0waoMA_bNiB4NlMRGlD-sSpOlRLUxYesAhS0M4VsIEpPto$=20

=3D =3D =3D
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FOUS30 KWBC 231551
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1151 AM EDT Wed Apr 23 2025

Day 1
Valid 16Z Wed Apr 23 2025 - 12Z Thu Apr 24 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE PLAINS AND THE SOUTHEAST...

...16Z Update...

Only minor changes were made to the large Marginal Risk area across
the Plains and Southeast this morning. From a review of an ensemble
of the CAMS to HREF probabilities, the Marginal Risk looks in
really good shape. Ongoing convection across Texas, Kansas, and=20
individual cells developing in the Southeast as well as expected
dryline storms in the southern Plains and MCS development further
north into NE/KS all remain in generally good agreement among the
guidance. The smaller details of those features, however, are far
from certain, lending to only "Marginal Risk" levels of confidence.
Regardless, for the vast majority of the area, impacts should=20
remain localized. Cell interactions and localized training may=20
cause more widely scattered flash flooding in a few areas, but high
uncertainty about where that may happen precludes any Slight Risk=20
upgrades at this time.=20

Wegman

...Previous Discussion...

Persistent Gulf moisture advecting northward through the Gulf
states over a stalled frontal boundary draped across the Southeast
will continue to produce scattered to widespread convection capable
of producing heavy rainfall. Rounds of showers and thunderstorms
will fire up along the the boundary from Texas to the Carolinas
with some training and backbuilding expected. Given there will be
very little movement of the front the storms are likely to track over
many of the same areas being impacted by ongoing showers and
storms of late, which locally increases the flash flooding risk. A
convective complex tracking east across the Hill Country during
the very early hours of Wednesday is spreading 0.5 to 1 inch/hour
rain rates along its path which may lead to isolated urban flash
flooding. Refer to WPC mesoscale precipitation discussion #160 for
more details.

The latest guidance has better confidence that the wettest areas
will likely focus over southern Nebraska and northern Kansas. This
too will be the result of an MCS or clusters of thunderstorms
developing and training multiple times over the same areas. The
Marginal remains in place as the consensus of heaviest rains on the
order of 1-2 inches (locally higher, of course) is in a portion of
Kansas and Nebraska that has largely missed out on recent heavy
rainfall, and the antecedent dry conditions should help to offset
and delay the greatest impacts from any heavy rain.

The area of the Marginal of least concern appears to be over
Oklahoma, which while seeing some scattered shower and thunderstorm
activity, should be between the MCSs/areas of more organized and
persistent convection. However, due to heavy rainfall, lower FFGs
over much of the state lower the threshold needed to achieve flash
flooding, so the Marginal is largely unchanged there.

Campbell/Wegman


Day 2
Valid 12Z Thu Apr 24 2025 - 12Z Fri Apr 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
KANSAS, OKLAHOMA, ARKANSAS AND MISSOURI...

Multiple clusters of thunderstorms will likely be ongoing in
different portions of the ERO risk areas at the start of the Day
3/Thursday time period. These MCS's will likely weaken and
dissipate through the late morning, as MCS's typically do. However,
with peak heating and the increased instability there will be
renewed rounds of showers and thunderstorms. Since this is likely
to occur over many of the same areas hit with recent heavy rain
this will once again renew the potential for localized flash
flooding over portions of the Southeast. Much of the guidance has
areal averages of 1 to 2 inches with higher maximums possible
falling over much of the same footprint in the day(s) prior. The
potential for a new MCS to form Thursday night will keep the
threat for flash flooding elevated. The inherited Slight Risk
remained largely untouched as it continued to reflect the areas
with the greater threat for flash flooding.

In similar fashion as Day 1, the low level jet will keep a steady
influx of Gulf moisture over the stalled boundary which will
maintain support for heavier rainfall with the strongest storms,
and greater coverage of showers and storms in general. A Marginal
Risk covers the northern Gulf states and Southeast.

Campbell


Day 3
Valid 12Z Fri Apr 25 2025 - 12Z Sat Apr 26 2025

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL MID-MISSISSIPPI VALLEY/Tennessee VALLEY TO PORTIONS OF THE NORTHEAST...

Recent and ongoing rainfall over some portions of this broad
region will make some areas susceptible to additional rains. During
this period a surface low pressure system and its attendant front
will likely track from the Mississippi Valley toward the Great
Lakes region and interior Northeast. This system will usher in
showers and thunderstorms to areas with increased soil saturation
and lower FFGs. The broad Marginal Risk was maintained from the
Tennessee Valley to the New Hampshire/Maine border given the
increasing signal for heavier and more widespread QPF.

Campbell

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!6eFga0Zxwcz8BHZLCLUMePNXI7SzlUu5nnavmmOUZ8DM= fBWTQ0dTBccukPl-1YgErmnMuohTZQqpfkfMz51AyVPXAoE$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!6eFga0Zxwcz8BHZLCLUMePNXI7SzlUu5nnavmmOUZ8DM= fBWTQ0dTBccukPl-1YgErmnMuohTZQqpfkfMz51AbY5S-bI$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!6eFga0Zxwcz8BHZLCLUMePNXI7SzlUu5nnavmmOUZ8DM= fBWTQ0dTBccukPl-1YgErmnMuohTZQqpfkfMz51A7vRNf6g$=20

=3D =3D =3D
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FOUS30 KWBC 231921
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
321 PM EDT Wed Apr 23 2025

Day 1
Valid 16Z Wed Apr 23 2025 - 12Z Thu Apr 24 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE PLAINS AND THE SOUTHEAST...

...16Z Update...

Only minor changes were made to the large Marginal Risk area across
the Plains and Southeast this morning. From a review of an ensemble
of the CAMS to HREF probabilities, the Marginal Risk looks in
really good shape. Ongoing convection across Texas, Kansas, and
individual cells developing in the Southeast as well as expected
dryline storms in the southern Plains and MCS development further
north into NE/KS all remain in generally good agreement among the
guidance. The smaller details of those features, however, are far
from certain, lending to only "Marginal Risk" levels of confidence.
Regardless, for the vast majority of the area, impacts should
remain localized. Cell interactions and localized training may
cause more widely scattered flash flooding in a few areas, but high
uncertainty about where that may happen precludes any Slight Risk
upgrades at this time.

Wegman

...Previous Discussion...

Persistent Gulf moisture advecting northward through the Gulf
states over a stalled frontal boundary draped across the Southeast
will continue to produce scattered to widespread convection capable
of producing heavy rainfall. Rounds of showers and thunderstorms
will fire up along the the boundary from Texas to the Carolinas
with some training and backbuilding expected. Given there will be
very little movement of the front the storms are likely to track over
many of the same areas being impacted by ongoing showers and
storms of late, which locally increases the flash flooding risk. A
convective complex tracking east across the Hill Country during
the very early hours of Wednesday is spreading 0.5 to 1 inch/hour
rain rates along its path which may lead to isolated urban flash
flooding. Refer to WPC mesoscale precipitation discussion #160 for
more details.

The latest guidance has better confidence that the wettest areas
will likely focus over southern Nebraska and northern Kansas. This
too will be the result of an MCS or clusters of thunderstorms
developing and training multiple times over the same areas. The
Marginal remains in place as the consensus of heaviest rains on the
order of 1-2 inches (locally higher, of course) is in a portion of
Kansas and Nebraska that has largely missed out on recent heavy
rainfall, and the antecedent dry conditions should help to offset
and delay the greatest impacts from any heavy rain.

The area of the Marginal of least concern appears to be over
Oklahoma, which while seeing some scattered shower and thunderstorm
activity, should be between the MCSs/areas of more organized and
persistent convection. However, due to heavy rainfall, lower FFGs
over much of the state lower the threshold needed to achieve flash
flooding, so the Marginal is largely unchanged there.

Campbell/Wegman


Day 2
Valid 12Z Thu Apr 24 2025 - 12Z Fri Apr 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE CENTRAL AND SOUTHERN PLAINS...

...1930Z Update...

The guidance surrounding the coverage and intensity of showers and thunderstorms across the country Thursday remains highly variable,
which has resulted in some bigger changes to the Day 2 outlook.
Generally, there have been increases in the forecast around Iowa,
Oklahoma and North Texas, and the southern Appalachians and north
Georgia. Meanwhile the main area of decreases was in Missouri and
Arkansas. As a result of these changes, the Slight Risk area was
trimmed on the eastern side largely out of Missouri and Arkansas,
and expanded south to cover portions of north Texas, including the
DFW Metroplex.

For the Marginal, it too was expanded west to cover the rest of
west Kansas and the eastern half of the Oklahoma Panhandle, the
eastern Texas Panhandle (for initiation of dryline convection
Thursday afternoon), and more significantly, was expanded north
into eastern Kentucky from the southern Appalachians. All of these
areas have had some heavy rain in recent days, resulting in
depressed FFGs. For DFW, that heavy rain was as recently as this
morning. Only an isolated flash flooding risk is expected in the
Marginal Risk area...with the urban centers assuming the brunt of
that risk.

Wegman

...Previous Discussion...

Multiple clusters of thunderstorms will likely be ongoing in
different portions of the ERO risk areas at the start of the Day
3/Thursday time period. These MCS's will likely weaken and
dissipate through the late morning, as MCS's typically do. However,
with peak heating and the increased instability there will be
renewed rounds of showers and thunderstorms. Since this is likely
to occur over many of the same areas hit with recent heavy rain
this will once again renew the potential for localized flash
flooding over portions of the Southeast. Much of the guidance has
areal averages of 1 to 2 inches with higher maximums possible
falling over much of the same footprint in the day(s) prior. The
potential for a new MCS to form Thursday night will keep the
threat for flash flooding elevated. The inherited Slight Risk
remained largely untouched as it continued to reflect the areas
with the greater threat for flash flooding.

In similar fashion as Day 1, the low level jet will keep a steady
influx of Gulf moisture over the stalled boundary which will
maintain support for heavier rainfall with the strongest storms,
and greater coverage of showers and storms in general. A Marginal
Risk covers the northern Gulf states and Southeast.

Campbell


Day 3
Valid 12Z Fri Apr 25 2025 - 12Z Sat Apr 26 2025

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN PLAINS, MID-MISSISSIPPI VALLEY, OHIO VALLEY, AND
PORTIONS OF THE NORTHEAST...

...1930Z Update...

A strengthening surface low developing ahead of a strengthening
upper level shortwave trough will drive the storms from a forcing
standpoint through the period. Starting in the Plains it will track
northeast into the Great Lakes Friday night, with showers and
storms forming along the cold front to the south and east of the
low center. This will bring periodically heavy rainfall to portions
of the Northeast, which has been in a drier period the past week.
Gulf moisture continuing to advect in from the south will lead to
shower and thunderstorm activity starting Friday afternoon across=20
the Tennessee and Ohio Valleys, and continuing into Friday night as
the front lags behind (south and west) of the surface low.
Meanwhile, the trailing (western) end of the cold front may be the
trigger for additional thunderstorms into southern Oklahoma, north
Texas, and the southern Texas Panhandle. For this reason (and
previous days' rains), the Marginal was expanded to cover this area
for an isolated flash flooding threat, though coverage of storms
looks to be significantly decreased on Friday in this area as
compared to previous days.

Wegman

...Previous Discussion...

Recent and ongoing rainfall over some portions of this broad
region will make some areas susceptible to additional rains. During
this period a surface low pressure system and its attendant front
will likely track from the Mississippi Valley toward the Great
Lakes region and interior Northeast. This system will usher in
showers and thunderstorms to areas with increased soil saturation
and lower FFGs. The broad Marginal Risk was maintained from the
Tennessee Valley to the New Hampshire/Maine border given the
increasing signal for heavier and more widespread QPF.

Campbell

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!-VQpffFNBPwUCo9Fpzm93loIubdQpxH7wuCE2etXOL5R= PofQV7key4fDoAfTojhRn6XIdX2oEQheeR37vubq8jAGgiw$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!-VQpffFNBPwUCo9Fpzm93loIubdQpxH7wuCE2etXOL5R= PofQV7key4fDoAfTojhRn6XIdX2oEQheeR37vubqUgYRMio$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!-VQpffFNBPwUCo9Fpzm93loIubdQpxH7wuCE2etXOL5R= PofQV7key4fDoAfTojhRn6XIdX2oEQheeR37vubqBjvew44$=20

=3D =3D =3D
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FOUS30 KWBC 240052
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
852 PM EDT Wed Apr 23 2025

Day 1
Valid 01Z Thu Apr 24 2025 - 12Z Thu Apr 24 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE PLAINS AND THE SOUTHEAST...


...01Z Update...
Broke the large Marginal Risk area into two areas--one area over
the western High Plains in vicinity of a surface dry line and the
second area extending from the Southern Mississippi Valley into
parts of the Tennessee Valley/Southeast US along and south of a quasi-stationary front which was acting as a focus. The HRRR/HREF
both have convection persisting into the late night/early morning
hours in the Plains...although the 23Z run from the HRRR tended to
focus activity and heaviest rainfall more in western Kansas than=20
elsewhere. The convection in from the Gulf states into the=20
southern Appalachians should taper off by late evening and=20
dissipate...but felt it was too early to remove the Marginal risk=20
area at this point.

Bann


...16Z Update...

Only minor changes were made to the large Marginal Risk area across
the Plains and Southeast this morning. From a review of an ensemble
of the CAMS to HREF probabilities, the Marginal Risk looks in
really good shape. Ongoing convection across Texas, Kansas, and
individual cells developing in the Southeast as well as expected
dryline storms in the southern Plains and MCS development further
north into NE/KS all remain in generally good agreement among the
guidance. The smaller details of those features, however, are far
from certain, lending to only "Marginal Risk" levels of confidence.
Regardless, for the vast majority of the area, impacts should
remain localized. Cell interactions and localized training may
cause more widely scattered flash flooding in a few areas, but high
uncertainty about where that may happen precludes any Slight Risk
upgrades at this time.

Wegman

...Previous Discussion...

Persistent Gulf moisture advecting northward through the Gulf
states over a stalled frontal boundary draped across the Southeast
will continue to produce scattered to widespread convection capable
of producing heavy rainfall. Rounds of showers and thunderstorms
will fire up along the the boundary from Texas to the Carolinas
with some training and backbuilding expected. Given there will be
very little movement of the front the storms are likely to track over
many of the same areas being impacted by ongoing showers and
storms of late, which locally increases the flash flooding risk. A
convective complex tracking east across the Hill Country during
the very early hours of Wednesday is spreading 0.5 to 1 inch/hour
rain rates along its path which may lead to isolated urban flash
flooding. Refer to WPC mesoscale precipitation discussion #160 for
more details.

The latest guidance has better confidence that the wettest areas
will likely focus over southern Nebraska and northern Kansas. This
too will be the result of an MCS or clusters of thunderstorms
developing and training multiple times over the same areas. The
Marginal remains in place as the consensus of heaviest rains on the
order of 1-2 inches (locally higher, of course) is in a portion of
Kansas and Nebraska that has largely missed out on recent heavy
rainfall, and the antecedent dry conditions should help to offset
and delay the greatest impacts from any heavy rain.

The area of the Marginal of least concern appears to be over
Oklahoma, which while seeing some scattered shower and thunderstorm
activity, should be between the MCSs/areas of more organized and
persistent convection. However, due to heavy rainfall, lower FFGs
over much of the state lower the threshold needed to achieve flash
flooding, so the Marginal is largely unchanged there.

Campbell/Wegman


Day 2
Valid 12Z Thu Apr 24 2025 - 12Z Fri Apr 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE CENTRAL AND SOUTHERN PLAINS...

...1930Z Update...

The guidance surrounding the coverage and intensity of showers and thunderstorms across the country Thursday remains highly variable,
which has resulted in some bigger changes to the Day 2 outlook.
Generally, there have been increases in the forecast around Iowa,
Oklahoma and North Texas, and the southern Appalachians and north
Georgia. Meanwhile the main area of decreases was in Missouri and
Arkansas. As a result of these changes, the Slight Risk area was
trimmed on the eastern side largely out of Missouri and Arkansas,
and expanded south to cover portions of north Texas, including the
DFW Metroplex.

For the Marginal, it too was expanded west to cover the rest of
west Kansas and the eastern half of the Oklahoma Panhandle, the
eastern Texas Panhandle (for initiation of dryline convection
Thursday afternoon), and more significantly, was expanded north
into eastern Kentucky from the southern Appalachians. All of these
areas have had some heavy rain in recent days, resulting in
depressed FFGs. For DFW, that heavy rain was as recently as this
morning. Only an isolated flash flooding risk is expected in the
Marginal Risk area...with the urban centers assuming the brunt of
that risk.

Wegman

...Previous Discussion...

Multiple clusters of thunderstorms will likely be ongoing in
different portions of the ERO risk areas at the start of the Day
3/Thursday time period. These MCS's will likely weaken and
dissipate through the late morning, as MCS's typically do. However,
with peak heating and the increased instability there will be
renewed rounds of showers and thunderstorms. Since this is likely
to occur over many of the same areas hit with recent heavy rain
this will once again renew the potential for localized flash
flooding over portions of the Southeast. Much of the guidance has
areal averages of 1 to 2 inches with higher maximums possible
falling over much of the same footprint in the day(s) prior. The
potential for a new MCS to form Thursday night will keep the
threat for flash flooding elevated. The inherited Slight Risk
remained largely untouched as it continued to reflect the areas
with the greater threat for flash flooding.

In similar fashion as Day 1, the low level jet will keep a steady
influx of Gulf moisture over the stalled boundary which will
maintain support for heavier rainfall with the strongest storms,
and greater coverage of showers and storms in general. A Marginal
Risk covers the northern Gulf states and Southeast.

Campbell


Day 3
Valid 12Z Fri Apr 25 2025 - 12Z Sat Apr 26 2025

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN PLAINS, MID-MISSISSIPPI VALLEY, OHIO VALLEY, AND
PORTIONS OF THE NORTHEAST...

...1930Z Update...

A strengthening surface low developing ahead of a strengthening
upper level shortwave trough will drive the storms from a forcing
standpoint through the period. Starting in the Plains it will track
northeast into the Great Lakes Friday night, with showers and
storms forming along the cold front to the south and east of the
low center. This will bring periodically heavy rainfall to portions
of the Northeast, which has been in a drier period the past week.
Gulf moisture continuing to advect in from the south will lead to
shower and thunderstorm activity starting Friday afternoon across
the Tennessee and Ohio Valleys, and continuing into Friday night as
the front lags behind (south and west) of the surface low.
Meanwhile, the trailing (western) end of the cold front may be the
trigger for additional thunderstorms into southern Oklahoma, north
Texas, and the southern Texas Panhandle. For this reason (and
previous days' rains), the Marginal was expanded to cover this area
for an isolated flash flooding threat, though coverage of storms
looks to be significantly decreased on Friday in this area as
compared to previous days.

Wegman

...Previous Discussion...

Recent and ongoing rainfall over some portions of this broad
region will make some areas susceptible to additional rains. During
this period a surface low pressure system and its attendant front
will likely track from the Mississippi Valley toward the Great
Lakes region and interior Northeast. This system will usher in
showers and thunderstorms to areas with increased soil saturation
and lower FFGs. The broad Marginal Risk was maintained from the
Tennessee Valley to the New Hampshire/Maine border given the
increasing signal for heavier and more widespread QPF.

Campbell

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!9zUTsbIVNT0GF0iY7GHAgvk3fE4T1JIA1WlXZO_Zrz1K= LeaR2R4r9fYCHiN7A-m2qkFFfDlmMtky9s0s-Rv2UTyjbjA$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!9zUTsbIVNT0GF0iY7GHAgvk3fE4T1JIA1WlXZO_Zrz1K= LeaR2R4r9fYCHiN7A-m2qkFFfDlmMtky9s0s-Rv23MfqAPk$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!9zUTsbIVNT0GF0iY7GHAgvk3fE4T1JIA1WlXZO_Zrz1K= LeaR2R4r9fYCHiN7A-m2qkFFfDlmMtky9s0s-Rv2I6hTsy4$=20

=3D =3D =3D
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FOUS30 KWBC 240759
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
359 AM EDT Thu Apr 24 2025

Day 1
Valid 12Z Thu Apr 24 2025 - 12Z Fri Apr 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE CENTRAL/SOUTHERN PLAINS AND IOWA...

The latest suite of guidance continues to be be highly variable=20
with the placement of highest QPF; however persisted with increases
over Iowa as well as Oklahoma and Texas. The Slight Risk saw a=20
southward expansion for the Hill Country and to the northeast=20
placing the northern boundary into central Iowa. Meanwhile there=20
was a reduction across western Oklahoma and along the Missouri and
Kansas border. Areal averages of 1 to 2 inches with local maximums
of 4+ inches possible.

Multiple clusters of thunderstorms will likely be ongoing. With peak
heating and the increased instability there will be renewed rounds
of showers and thunderstorms. Since this is likely to occur over=20
many of the same areas hit with recent heavy rain this will once=20
again renew the potential for localized flash flooding over=20
portions of the Southeast. There will be a steady influx of Gulf=20
moisture streaming over the stalled boundary which will maintain=20
support for heavier rainfall with the strongest storms, and greater
coverage of showers and storms in general. A Marginal Risk covers=20
the northern Gulf states and Southeast.

Campbell


Day 2
Valid 12Z Fri Apr 25 2025 - 12Z Sat Apr 26 2025

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN PLAINS, MID-MISSISSIPPI VALLEY, OHIO VALLEY, AND
PORTIONS OF THE NORTHEAST...

A strengthening surface low developing ahead of a strengthening
upper level shortwave trough will drive the storms from a forcing
standpoint through the period. Starting in the Plains it will track
northeast into the Great Lakes Friday evening, with showers and=20
storms forming along the cold front to the south and east of the=20
low center. This will bring periodically heavy rainfall to=20
portions of the Northeast, which has been in a drier period the=20
past week. Gulf moisture continuing to advect in from the south=20
will lead to shower and thunderstorm activity starting Friday=20
afternoon across the Tennessee and Ohio Valleys, and continuing=20
into Friday night as the front lags behind (south and west) of the=20
surface low. Meanwhile, the trailing (western) end of the cold=20
front may be the trigger for additional thunderstorms into southern
Oklahoma, north Texas, and the southern Texas Panhandle.=20

In coordination will the offices in the Northeast the Marginal Risk
was removed from New Hampshire, Vermont, much of New York and
northeast Pennsylvania. This area has been drier of late and with
green up already in progress, much of the rain will be absorbed
with minimal if any flooding possible. Elsewhere, the Marginal had
minor reshaping to reflect the latest WPC QPF and model trends.

Campbell/Wegman


Day 3
Valid 12Z Sat Apr 26 2025 - 12Z Sun Apr 27 2025

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN PLAINS AND FOR PORTIONS OF NEW ENGLAND...

...New England...

Showers and thunderstorms are expected to pass through New England
thanks to upper level shortwave energy and wavy surface fronts.=20
The flow is expected to be fairly progressive so it will help limit
the potential for flash flood. Given the recent QPF trends and=20
placement, the inherited Marginal Risk area was significantly=20
modified to only include northeast Vermont, northern New Hampshire=20
and the majority of the state of Maine.=20

...Southern Plains...

The steady influx of rich moisture ahead of a deeply strengthening
storm system ejecting into the Plains will fuel rounds of heavy=20
rain and thunderstorms across portions of the central U.S. from the
weekend into next week. Guidance has improved its focus on where
the higher QPF will occur. The old Day 4 Marginal Risk was reduced
out of Nebraska and Kansas, now spanning from Texas to western
Arkansas as the new Marginal Risk area for this period. Heavy rain
will be favorable with the upper trough diffluence combined with=20 front/dryline instabilities.

Campbell


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!-YzSAaXAoiCA7YSOrhljjwIE5bBs-U01S_OG4tpbD_ki= Zg5J6TsxvpOGc26GoW4RR4wXu_5WX5jU8nKYzREfmzX7WYI$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!-YzSAaXAoiCA7YSOrhljjwIE5bBs-U01S_OG4tpbD_ki= Zg5J6TsxvpOGc26GoW4RR4wXu_5WX5jU8nKYzREftrOTn8Y$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!-YzSAaXAoiCA7YSOrhljjwIE5bBs-U01S_OG4tpbD_ki= Zg5J6TsxvpOGc26GoW4RR4wXu_5WX5jU8nKYzREfMZyPDBE$=20

=3D =3D =3D
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FOUS30 KWBC 241402
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1002 AM EDT Thu Apr 24 2025

Day 1
Valid 12Z Thu Apr 24 2025 - 12Z Fri Apr 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR EASTERN
LOUISIANA AND PORTIONS OF THE CENTRAL/SOUTHERN PLAINS AND IOWA...

...14Z Special Update...

A long-lived prolific heavy rainfall making MCS continues to drift
slowly across eastern Louisiana this morning. Given its history of
flash flood producing rains, a double upgrade to a Slight has been
issued for the area. For more details, see the associated Mesoscale Precipitation Discussion #169 just issued at=20 wpc.ncep.noaa.gov/metwatch/metwatch_mpd_multi.php?md=3D0169&yr=3D2025.

Wegman

...Previous Discussion...

The latest suite of guidance continues to be be highly variable
with the placement of highest QPF; however persisted with increases
over Iowa as well as Oklahoma and Texas. The Slight Risk saw a
southward expansion for the Hill Country and to the northeast
placing the northern boundary into central Iowa. Meanwhile there
was a reduction across western Oklahoma and along the Missouri and
Kansas border. Areal averages of 1 to 2 inches with local maximums
of 4+ inches possible.

Multiple clusters of thunderstorms will likely be ongoing. With peak
heating and the increased instability there will be renewed rounds
of showers and thunderstorms. Since this is likely to occur over
many of the same areas hit with recent heavy rain this will once
again renew the potential for localized flash flooding over
portions of the Southeast. There will be a steady influx of Gulf
moisture streaming over the stalled boundary which will maintain
support for heavier rainfall with the strongest storms, and greater
coverage of showers and storms in general. A Marginal Risk covers
the northern Gulf states and Southeast.

Campbell


Day 2
Valid 12Z Fri Apr 25 2025 - 12Z Sat Apr 26 2025

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN PLAINS, MID-MISSISSIPPI VALLEY, OHIO VALLEY, AND
PORTIONS OF THE NORTHEAST...

A strengthening surface low developing ahead of a strengthening
upper level shortwave trough will drive the storms from a forcing
standpoint through the period. Starting in the Plains it will track
northeast into the Great Lakes Friday evening, with showers and
storms forming along the cold front to the south and east of the
low center. This will bring periodically heavy rainfall to
portions of the Northeast, which has been in a drier period the
past week. Gulf moisture continuing to advect in from the south
will lead to shower and thunderstorm activity starting Friday
afternoon across the Tennessee and Ohio Valleys, and continuing
into Friday night as the front lags behind (south and west) of the
surface low. Meanwhile, the trailing (western) end of the cold
front may be the trigger for additional thunderstorms into southern
Oklahoma, north Texas, and the southern Texas Panhandle.

In coordination will the offices in the Northeast the Marginal Risk
was removed from New Hampshire, Vermont, much of New York and
northeast Pennsylvania. This area has been drier of late and with
green up already in progress, much of the rain will be absorbed
with minimal if any flooding possible. Elsewhere, the Marginal had
minor reshaping to reflect the latest WPC QPF and model trends.

Campbell/Wegman


Day 3
Valid 12Z Sat Apr 26 2025 - 12Z Sun Apr 27 2025

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN PLAINS AND FOR PORTIONS OF NEW ENGLAND...

...New England...

Showers and thunderstorms are expected to pass through New England
thanks to upper level shortwave energy and wavy surface fronts.
The flow is expected to be fairly progressive so it will help limit
the potential for flash flood. Given the recent QPF trends and
placement, the inherited Marginal Risk area was significantly
modified to only include northeast Vermont, northern New Hampshire
and the majority of the state of Maine.

...Southern Plains...

The steady influx of rich moisture ahead of a deeply strengthening
storm system ejecting into the Plains will fuel rounds of heavy
rain and thunderstorms across portions of the central U.S. from the
weekend into next week. Guidance has improved its focus on where
the higher QPF will occur. The old Day 4 Marginal Risk was reduced
out of Nebraska and Kansas, now spanning from Texas to western
Arkansas as the new Marginal Risk area for this period. Heavy rain
will be favorable with the upper trough diffluence combined with
front/dryline instabilities.

Campbell


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!6tX8p4SozC8VDSI5z8vyve5vo7JkFNdvDi6SJsRJsq2N= 3pZ067U5M1vi6D_dGuQFVWvpv2fxnKUY42Vv4HHa2bmu300$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!6tX8p4SozC8VDSI5z8vyve5vo7JkFNdvDi6SJsRJsq2N= 3pZ067U5M1vi6D_dGuQFVWvpv2fxnKUY42Vv4HHa6Sl1iio$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!6tX8p4SozC8VDSI5z8vyve5vo7JkFNdvDi6SJsRJsq2N= 3pZ067U5M1vi6D_dGuQFVWvpv2fxnKUY42Vv4HHakhGaVfE$=20

=3D =3D =3D
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FOUS30 KWBC 242000
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
400 PM EDT Thu Apr 24 2025

Day 1
Valid 16Z Thu Apr 24 2025 - 12Z Fri Apr 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR EASTERN
LOUISIANA, NORTHEAST TEXAS, AND NORTHEASTERN KANSAS THROUGH CENTRAL
IOWA...

...16Z Update...

The inherited Slight Risk across much of the Plains was divided
into two much smaller risk areas with this update, with the middle
carved out back down to a Marginal. The CAMs guidance has been in
poor agreement regarding how these MCSs, as well as any new
convection later this afternoon, will behave through tonight. Where
there is at least some consensus among the guidance is for greater
amounts of convection in the new, smaller Slight Risk areas and
less in the middle, which was the catalyst behind dividing the
Slight.

...Eastern Louisiana...

The newly issued Slight in eastern Louisiana is in place for an
ongoing MCS that has a history of producing rainfall rates of 2-4
inches per hour, along with training and backbuilding that has
allowed this heavy rainfall to occur over a small area for an
extended period of time. On the whole the MCS has been weakening,
but local cores with rates that high continue this morning. CAMs
guidance is in reasonable agreement that some level of heavy rain
from convection will continue in this area, likely north of Lake
Pontchartrain, through 18Z. It appears likely that this Slight
will be able to be downgraded this afternoon with higher confidence
in the convective trends.

...Northeast Texas...

The southern end of the previous Slight has been expanded south and
east in response to a much more robust MCS (compared to the one in
Louisiana) across northern Texas this morning. Individual cores of
heavy rain have been far more persistent into the late morning, and
have developed into an east-west oriented line that is now
generally south of the I-20 corridor, and fortunately well south
and west of the Dallas-Fort Worth Metroplex. While urban concerns
remain heightened in the Metroplex for the possibility of
additional storm development this afternoon, the greatest near term
concerns will be between I-20 and I-35 in central Texas. With peak
heating, expect additional storms to develop south of the current
storms in the area of greatest inflow of moisture and instability.

...Kansas to Iowa...

Multiple small clusters of storms from northern Kansas through
central Iowa are largely weakening this morning. However, there is
some CAMs consensus that additional strong convection will break
out in southeast Nebraska this afternoon. This convection will
advect northeast into Iowa, where previous rounds of heavy rain
have depressed FFGs. Thus, despite a lower likelihood of training
and faster moving cells, the low-confidence Slight remains in place
with a small expansion northeast further into central Iowa based on
the trends in the guidance. There remains some possibility tonight
that additional convection will fire along remnant outflow
boundaries in northern Kansas where the current line of showers has
already cleared, which is why for now the Slight remains for that
area.

...Marginal Risk...

Elsewhere, as mentioned above expect a relative minimum of
convection over most of Oklahoma and southern Kansas today and
tonight, though isolated cells remain very possible. For the
Southeast, no changes were made, with expected individual cells or
small clusters of storms developing this afternoon with peak
heating. The coverage of storms in this area is unlikely to be very
robust, precluded the need for a Slight Risk upgrade for now.

Wegman


Day 2
Valid 12Z Fri Apr 25 2025 - 12Z Sat Apr 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
NORTH TEXAS AND SOUTHWEST OKLAHOMA...

...2030Z Update...

In coordination with LUB/Lubbock, TX and SJT/San Angelo, TX
forecast offices, a Slight Risk was hoisted for portions of north
Texas and southwest Oklahoma this afternoon. Surprisingly good
agreement among the 12Z suite of CAMs guidance suggests persistent
and slow-moving thunderstorms will develop across this region
Friday afternoon. The storms will likely initiate along the
dryline, and congeal Friday evening into an MCS. The forecast for
the individual cells contained within the MCS is uncertain for
Friday night, but there is some concern that stronger
storms/supercells may be stalled or very slow moving, causing
localized flash flooding impacts, while the MCS as a whole remains
over an area hard hit with heavy rain in recent days.

The Marginal Risk remains in place over much of the Midwest and
Tennessee Valleys for more stratiform, but longer lived rainfall
across the region, with embedded convection that may cause isolated
instances of flash flooding, especially in the lower FFG areas hit
with heavy rain recently, resulting in locally saturated soils. The
Marginal Risk into Arkansas and Missouri was removed with this
update as it appears more likely that the MCS out west and the
rainfall across the east remain separate.

Wegman

...Previous Discussion...

A strengthening surface low developing ahead of a strengthening
upper level shortwave trough will drive the storms from a forcing
standpoint through the period. Starting in the Plains it will track
northeast into the Great Lakes Friday evening, with showers and
storms forming along the cold front to the south and east of the
low center. This will bring periodically heavy rainfall to
portions of the Northeast, which has been in a drier period the
past week. Gulf moisture continuing to advect in from the south
will lead to shower and thunderstorm activity starting Friday
afternoon across the Tennessee and Ohio Valleys, and continuing
into Friday night as the front lags behind (south and west) of the
surface low. Meanwhile, the trailing (western) end of the cold
front may be the trigger for additional thunderstorms into southern
Oklahoma, north Texas, and the southern Texas Panhandle.

In coordination will the offices in the Northeast the Marginal Risk
was removed from New Hampshire, Vermont, much of New York and
northeast Pennsylvania. This area has been drier of late and with
green up already in progress, much of the rain will be absorbed
with minimal if any flooding possible. Elsewhere, the Marginal had
minor reshaping to reflect the latest WPC QPF and model trends.

Campbell/Wegman


Day 3
Valid 12Z Sat Apr 26 2025 - 12Z Sun Apr 27 2025

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN PLAINS...

...2030Z Update...

...Southern Plains...

An MCS that developed over the Texas Panhandle Friday and Friday
night will persist into Saturday across the Marginal Risk area,
with less areal coverage of rain on Saturday as compared with
Friday. Uncertainty regarding MCS behavior on Saturday remains very
high, and further updates and the move of this time frame into CAMs
range may require a later upgrade to a Slight, particularly if
heavy rain remains further west towards the Panhandle for longer.
Regardless, additional convection is likely to form again Saturday
afternoon along the dryline near the New Mexico border, which may
further worsen flooding concerns in the areas where the storms
develop.

...New England...

Does an inch of rain in Maine fall swiftly enough to cause pain?
The answer is no, so the Marginal has been removed.=20

Largely stratiform rain and the fast movement of the rainfall=20
plume over soils that are at or drier than normal should preclude=20
flash flooding in this area.

Wegman


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!8t4UCo-GRYlsmFNI3tlNhGjRt3cbzfZRjSKYuXiS7ahl= yYxHGqJF8x-Nn8b2ICcNgEy7f1xibDimqqh9nvKHhfB-ae0$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!8t4UCo-GRYlsmFNI3tlNhGjRt3cbzfZRjSKYuXiS7ahl= yYxHGqJF8x-Nn8b2ICcNgEy7f1xibDimqqh9nvKH7SrvKsQ$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!8t4UCo-GRYlsmFNI3tlNhGjRt3cbzfZRjSKYuXiS7ahl= yYxHGqJF8x-Nn8b2ICcNgEy7f1xibDimqqh9nvKH0ehm9SY$=20

=3D =3D =3D
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FOUS30 KWBC 241551
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1151 AM EDT Thu Apr 24 2025

Day 1
Valid 12Z Thu Apr 24 2025 - 12Z Fri Apr 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR EASTERN
LOUISIANA, NORTHEAST TEXAS, AND NORTHEASTERN KANSAS THROUGH CENTRAL=20
IOWA...

...16Z Update...

The inherited Slight Risk across much of the Plains was divided
into two much smaller risk areas with this update, with the middle
carved out back down to a Marginal. The CAMs guidance has been in
poor agreement regarding how these MCSs, as well as any new
convection later this afternoon, will behave through tonight. Where
there is at least some consensus among the guidance is for greater
amounts of convection in the new, smaller Slight Risk areas and
less in the middle, which was the catalyst behind dividing the
Slight.

...Eastern Louisiana...

The newly issued Slight in eastern Louisiana is in place for an
ongoing MCS that has a history of producing rainfall rates of 2-4
inches per hour, along with training and backbuilding that has
allowed this heavy rainfall to occur over a small area for an
extended period of time. On the whole the MCS has been weakening,
but local cores with rates that high continue this morning. CAMs
guidance is in reasonable agreement that some level of heavy rain
from convection will continue in this area, likely north of Lake
Pontchartrain, through 18Z. It appears likely that this Slight=20
will be able to be downgraded this afternoon with higher confidence
in the convective trends.

...Northeast Texas...

The southern end of the previous Slight has been expanded south and
east in response to a much more robust MCS (compared to the one in
Louisiana) across northern Texas this morning. Individual cores of
heavy rain have been far more persistent into the late morning, and
have developed into an east-west oriented line that is now
generally south of the I-20 corridor, and fortunately well south
and west of the Dallas-Fort Worth Metroplex. While urban concerns
remain heightened in the Metroplex for the possibility of
additional storm development this afternoon, the greatest near term
concerns will be between I-20 and I-35 in central Texas. With peak
heating, expect additional storms to develop south of the current
storms in the area of greatest inflow of moisture and instability.

...Kansas to Iowa...

Multiple small clusters of storms from northern Kansas through=20
central Iowa are largely weakening this morning. However, there is
some CAMs consensus that additional strong convection will break
out in southeast Nebraska this afternoon. This convection will=20
advect northeast into Iowa, where previous rounds of heavy rain
have depressed FFGs. Thus, despite a lower likelihood of training
and faster moving cells, the low-confidence Slight remains in place
with a small expansion northeast further into central Iowa based on
the trends in the guidance. There remains some possibility tonight
that additional convection will fire along remnant outflow
boundaries in northern Kansas where the current line of showers has
already cleared, which is why for now the Slight remains for that
area.

...Marginal Risk...

Elsewhere, as mentioned above expect a relative minimum of
convection over most of Oklahoma and southern Kansas today and
tonight, though isolated cells remain very possible. For the
Southeast, no changes were made, with expected individual cells or
small clusters of storms developing this afternoon with peak
heating. The coverage of storms in this area is unlikely to be very
robust, precluded the need for a Slight Risk upgrade for now.

Wegman


Day 2
Valid 12Z Fri Apr 25 2025 - 12Z Sat Apr 26 2025

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN PLAINS, MID-MISSISSIPPI VALLEY, OHIO VALLEY, AND
PORTIONS OF THE NORTHEAST...

A strengthening surface low developing ahead of a strengthening
upper level shortwave trough will drive the storms from a forcing
standpoint through the period. Starting in the Plains it will track
northeast into the Great Lakes Friday evening, with showers and
storms forming along the cold front to the south and east of the
low center. This will bring periodically heavy rainfall to
portions of the Northeast, which has been in a drier period the
past week. Gulf moisture continuing to advect in from the south
will lead to shower and thunderstorm activity starting Friday
afternoon across the Tennessee and Ohio Valleys, and continuing
into Friday night as the front lags behind (south and west) of the
surface low. Meanwhile, the trailing (western) end of the cold
front may be the trigger for additional thunderstorms into southern
Oklahoma, north Texas, and the southern Texas Panhandle.

In coordination will the offices in the Northeast the Marginal Risk
was removed from New Hampshire, Vermont, much of New York and
northeast Pennsylvania. This area has been drier of late and with
green up already in progress, much of the rain will be absorbed
with minimal if any flooding possible. Elsewhere, the Marginal had
minor reshaping to reflect the latest WPC QPF and model trends.

Campbell/Wegman


Day 3
Valid 12Z Sat Apr 26 2025 - 12Z Sun Apr 27 2025

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN PLAINS AND FOR PORTIONS OF NEW ENGLAND...

...New England...

Showers and thunderstorms are expected to pass through New England
thanks to upper level shortwave energy and wavy surface fronts.
The flow is expected to be fairly progressive so it will help limit
the potential for flash flood. Given the recent QPF trends and
placement, the inherited Marginal Risk area was significantly
modified to only include northeast Vermont, northern New Hampshire
and the majority of the state of Maine.

...Southern Plains...

The steady influx of rich moisture ahead of a deeply strengthening
storm system ejecting into the Plains will fuel rounds of heavy
rain and thunderstorms across portions of the central U.S. from the
weekend into next week. Guidance has improved its focus on where
the higher QPF will occur. The old Day 4 Marginal Risk was reduced
out of Nebraska and Kansas, now spanning from Texas to western
Arkansas as the new Marginal Risk area for this period. Heavy rain
will be favorable with the upper trough diffluence combined with
front/dryline instabilities.

Campbell


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!53Z3_ZXfuqqWIKCcZW6uvrFfLEZ_l7GWquugYHYLJli2= rBemngICvubmNiBvKJJe-vhQeBc8LF6--PP1e_bH-w16tt0$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!53Z3_ZXfuqqWIKCcZW6uvrFfLEZ_l7GWquugYHYLJli2= rBemngICvubmNiBvKJJe-vhQeBc8LF6--PP1e_bHaSfndrM$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!53Z3_ZXfuqqWIKCcZW6uvrFfLEZ_l7GWquugYHYLJli2= rBemngICvubmNiBvKJJe-vhQeBc8LF6--PP1e_bHgu7OdcM$=20

=3D =3D =3D
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FOUS30 KWBC 250057
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
857 PM EDT Thu Apr 24 2025

Day 1
Valid 01Z Fri Apr 25 2025 - 12Z Fri Apr 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR EASTERN
LOUISIANA and NORTHEAST TEXAS, AND NORTHEASTERN KANSAS THROUGH=20
CENTRAL IOWA...


...01Z Update...
Removed one of the remaining two Slight risks given the history of
convection through the afternoon and fairly limited additional
amounts of rainfall expected during the overnight. Combined with
dry antecedent conditions across Iowa...removed the northern most
Slight risk area but maintained a low-confidence Marginal given the
strength of on-going convection and its potential for isolated
heavy rainfall rates before convection tapers off. Farther
south...maintained the broad Marginal risk area across the western
High Plains eastward across the Central and Southern Plains with=20
an embedded Slight Risk over part of eastern Texas based on short=20
term radar trends which supported the earlier high-res guidance.=20
Removed the Marginal risk area farther east as convection weakens=20
and dissipates with the loss of daytime heating.=20

Bann


...16Z Update...

The inherited Slight Risk across much of the Plains was divided
into two much smaller risk areas with this update, with the middle
carved out back down to a Marginal. The CAMs guidance has been in
poor agreement regarding how these MCSs, as well as any new
convection later this afternoon, will behave through tonight. Where
there is at least some consensus among the guidance is for greater
amounts of convection in the new, smaller Slight Risk areas and
less in the middle, which was the catalyst behind dividing the
Slight.

...Eastern Louisiana...

The newly issued Slight in eastern Louisiana is in place for an
ongoing MCS that has a history of producing rainfall rates of 2-4
inches per hour, along with training and backbuilding that has
allowed this heavy rainfall to occur over a small area for an
extended period of time. On the whole the MCS has been weakening,
but local cores with rates that high continue this morning. CAMs
guidance is in reasonable agreement that some level of heavy rain
from convection will continue in this area, likely north of Lake
Pontchartrain, through 18Z. It appears likely that this Slight
will be able to be downgraded this afternoon with higher confidence
in the convective trends.

...Northeast Texas...

The southern end of the previous Slight has been expanded south and
east in response to a much more robust MCS (compared to the one in
Louisiana) across northern Texas this morning. Individual cores of
heavy rain have been far more persistent into the late morning, and
have developed into an east-west oriented line that is now
generally south of the I-20 corridor, and fortunately well south
and west of the Dallas-Fort Worth Metroplex. While urban concerns
remain heightened in the Metroplex for the possibility of
additional storm development this afternoon, the greatest near term
concerns will be between I-20 and I-35 in central Texas. With peak
heating, expect additional storms to develop south of the current
storms in the area of greatest inflow of moisture and instability.

...Kansas to Iowa...

Multiple small clusters of storms from northern Kansas through
central Iowa are largely weakening this morning. However, there is
some CAMs consensus that additional strong convection will break
out in southeast Nebraska this afternoon. This convection will
advect northeast into Iowa, where previous rounds of heavy rain
have depressed FFGs. Thus, despite a lower likelihood of training
and faster moving cells, the low-confidence Slight remains in place
with a small expansion northeast further into central Iowa based on
the trends in the guidance. There remains some possibility tonight
that additional convection will fire along remnant outflow
boundaries in northern Kansas where the current line of showers has
already cleared, which is why for now the Slight remains for that
area.

...Marginal Risk...

Elsewhere, as mentioned above expect a relative minimum of
convection over most of Oklahoma and southern Kansas today and
tonight, though isolated cells remain very possible. For the
Southeast, no changes were made, with expected individual cells or
small clusters of storms developing this afternoon with peak
heating. The coverage of storms in this area is unlikely to be very
robust, precluded the need for a Slight Risk upgrade for now.

Wegman


Day 2
Valid 12Z Fri Apr 25 2025 - 12Z Sat Apr 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
NORTH TEXAS AND SOUTHWEST OKLAHOMA...

...2030Z Update...

In coordination with LUB/Lubbock, TX and SJT/San Angelo, TX
forecast offices, a Slight Risk was hoisted for portions of north
Texas and southwest Oklahoma this afternoon. Surprisingly good
agreement among the 12Z suite of CAMs guidance suggests persistent
and slow-moving thunderstorms will develop across this region
Friday afternoon. The storms will likely initiate along the
dryline, and congeal Friday evening into an MCS. The forecast for
the individual cells contained within the MCS is uncertain for
Friday night, but there is some concern that stronger
storms/supercells may be stalled or very slow moving, causing
localized flash flooding impacts, while the MCS as a whole remains
over an area hard hit with heavy rain in recent days.

The Marginal Risk remains in place over much of the Midwest and
Tennessee Valleys for more stratiform, but longer lived rainfall
across the region, with embedded convection that may cause isolated
instances of flash flooding, especially in the lower FFG areas hit
with heavy rain recently, resulting in locally saturated soils. The
Marginal Risk into Arkansas and Missouri was removed with this
update as it appears more likely that the MCS out west and the
rainfall across the east remain separate.

Wegman

...Previous Discussion...

A strengthening surface low developing ahead of a strengthening
upper level shortwave trough will drive the storms from a forcing
standpoint through the period. Starting in the Plains it will track
northeast into the Great Lakes Friday evening, with showers and
storms forming along the cold front to the south and east of the
low center. This will bring periodically heavy rainfall to
portions of the Northeast, which has been in a drier period the
past week. Gulf moisture continuing to advect in from the south
will lead to shower and thunderstorm activity starting Friday
afternoon across the Tennessee and Ohio Valleys, and continuing
into Friday night as the front lags behind (south and west) of the
surface low. Meanwhile, the trailing (western) end of the cold
front may be the trigger for additional thunderstorms into southern
Oklahoma, north Texas, and the southern Texas Panhandle.

In coordination will the offices in the Northeast the Marginal Risk
was removed from New Hampshire, Vermont, much of New York and
northeast Pennsylvania. This area has been drier of late and with
green up already in progress, much of the rain will be absorbed
with minimal if any flooding possible. Elsewhere, the Marginal had
minor reshaping to reflect the latest WPC QPF and model trends.

Campbell/Wegman


Day 3
Valid 12Z Sat Apr 26 2025 - 12Z Sun Apr 27 2025

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN PLAINS...

...2030Z Update...

...Southern Plains...

An MCS that developed over the Texas Panhandle Friday and Friday
night will persist into Saturday across the Marginal Risk area,
with less areal coverage of rain on Saturday as compared with
Friday. Uncertainty regarding MCS behavior on Saturday remains very
high, and further updates and the move of this time frame into CAMs
range may require a later upgrade to a Slight, particularly if
heavy rain remains further west towards the Panhandle for longer.
Regardless, additional convection is likely to form again Saturday
afternoon along the dryline near the New Mexico border, which may
further worsen flooding concerns in the areas where the storms
develop.

...New England...

Does an inch of rain in Maine fall swiftly enough to cause pain?
The answer is no, so the Marginal has been removed.

Largely stratiform rain and the fast movement of the rainfall
plume over soils that are at or drier than normal should preclude
flash flooding in this area.

Wegman


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!5jY6hNwnfkf8cNb1_Diaa2SyQn-8L0FQVi7N7JsK5dKm= Sz6zQLSoef5ZSBaGvyHG7lBk253qtx_rgym0flc0sEwjLEA$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!5jY6hNwnfkf8cNb1_Diaa2SyQn-8L0FQVi7N7JsK5dKm= Sz6zQLSoef5ZSBaGvyHG7lBk253qtx_rgym0flc05w15YIc$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!5jY6hNwnfkf8cNb1_Diaa2SyQn-8L0FQVi7N7JsK5dKm= Sz6zQLSoef5ZSBaGvyHG7lBk253qtx_rgym0flc0vjF0ugM$=20

=3D =3D =3D
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FOUS30 KWBC 250826
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
426 AM EDT Fri Apr 25 2025

Day 1
Valid 12Z Fri Apr 25 2025 - 12Z Sat Apr 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
NORTH TEXAS AND THE TEXAS PANHANDLE INTO SOUTHWEST OKLAHOMA...

...Summary...
Minor adjustments were made to the Slight Risk from yesterday's Day
2 ERO area across western portions of the TX/OK Red River Valley=20
into the Cap Rock and Rolling Plains. Meanwhile, the Marginal Risk
area farther east was extended to include more of the Lower MS
Valley.

...North TX...Central OK...TX-OK Panhandles...Eastern NM=20
Slight Risk area which was hoisted yesterday in the Day 2 ERO, in=20 coordination with affected TX/OK offices, continues into today's
Day 1 ERO with minor modifications. Upper level flow gradually becomes
more difluent today and tonight as the upper ridge axis pushes east
across the Southern Plains. Convection early this morning on the=20
leading edge of the outflow boundary south of the MCS will continue
to diminish south of the Red River, resulting in not much rainfall
from an areal-average standpoint. However, late this afternoon and
into the evening with the daytime heating and more favorable
forcing (increasing difluence aloft), additional storms will=20
develop along the dryline, likely growing upscale into an MCS that
will track slowly across the TX Panhandle and Red River Valley=20
into the overnight hours. The activity will parallel a W-E oriented
surface frontal boundary that will become quasi-stationary=20
overnight. The 00Z high-res guidance again indicated stronger
multicellular clusters and supercells, some of which become slow
moving per the simulated reflectivity guidance. Therefore there is
still concern that stronger storms/supercells within the MCS may=20
move more slowly or even stall, causing a more enhanced flash=20
flood risk, while the MCS as a whole remains over an area hard hit
with heavy rain in recent days. Within the Slight Risk area, the
latest (00Z) HREF shows highest probabilities of >5" within 12hrs
(40-50+ percent). Meanwhile, the Slight Risk area is also supported
by the latest UFVS-verified CSU ERO First Guess field.

...Lower-Mid MS Valley and TN Valley to OH Valley and Lower Great=20
Lakes, Southern-Central Appalachians...
The Marginal Risk inherited from yesterday's Day 2 ERO was expanded
to include more of the Lower MS Valley and a little more of the Mid
Atlantic Region. Over northern areas, deep-layer instability ahead
of the cold front is largely elevated and rather meager (less than
1000 J/Kg). However given the higher relative soil moisture and
lower FFGs over these areas, embedded convective elements may cause
isolated instances of flash flooding.=20

Farther south across the TN Valley and towards the Gulf Coast,=20
instability will be more plentiful (Mixed-layer CAPEs of 1000-1500=20
J/Kg), while TPW values are a bit more favorable as well (between=20
1.5-1.7"). Despite the more favorable thermodynamic profiles, the
more transient easterly progression of the shortwave energy will
limit the duration of the heaviest rainfall. Still, more elevated
1-2"+/hr probabilities in these areas may lead to localized short-
term runoff issues.

Hurley


Day 2
Valid 12Z Sat Apr 26 2025 - 12Z Sun Apr27 2025

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN PLAINS INTO THE SOUTHERN OZARKS AND JUST WEST OF THE
MISSISSIPPI DELTA...

...Southern Plains...
The MCS that is expected to traverse the Texas Panhandle and along
the Red River Valley Friday evening and overnight will persist=20
into Saturday across the Marginal Risk area. Guidance continues to
show more limited areal coverage of rain on Saturday as compared=20
with Friday with any additional convection that develops along the
dryline and the quasi-stationary west-to-east front. This=20
stationary front will eventually lift northeast as a warm front=20
Saturday night, taking the more organized/widespread convection=20
with it. Uncertainty regarding MCS behavior on Saturday remains=20
very high, and further updates and the move of this time frame into
CAMs range may require a later upgrade to a Slight, particularly=20
if heavy rain remains further west towards the Panhandle for=20
longer. Regardless, additional convection is likely to form again=20
Saturday afternoon along the dryline near the New Mexico border,=20
which may further worsen flooding concerns in the areas where the=20
storms develop.

Hurley/Wegman


Day 3
Valid 12Z Sun Apr 27 2025 - 12Z Mon Apr 28 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PARTS OF
THE GREAT BASIN AND FROM PORTIONS OF THE NORTHERN ROCKIES INTO THE
NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY...

Mid-upper trough across the southern Great Basin early Sunday will
lift across the central Rockies by 12Z Monday. This in-turn will
nudge the upper ridge axis east of the Northern Plains and Upper MS
Valley late Sunday-Sunday night, with a quick onset of upper level
divergence in its wake. Along with the more favorable dynamical
forcing (upper divergence and deep-layer ascent), deepening
southerly flow will tap the western Gulf and lead to an uptick in
low-mid layer moisture transport, with TPW values climbing to=20
1.25+ inches. Deep-layer instability meanwhile will also be ramping
up, to the tune of 1000-2000+ J/Kg MUCAPE per the 00Z GFS. Some of
the guidance (particularly the ECMWF) shows an MCS developing along
the western periphery of the upper ridge, then tracking east to
eventually southeast along the 850-300 mb thickness. At this point
(day 3 forecast) the forward-propagating Corfidi vectors would
support a more progressive MCS, though much will depend on the
strength of the LLJ. For now, have maintained a fairly broad
Marginal Risk area given the potential of intense short-term
(sub-3hr) rainfall rates.

Hurley


Day 1 threat area:=20 https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt= __;!!DZ3fjg!6eLTiZTG4OPC3cyWa-B-IqOvW45tRnoWQ2sYa5GtLevFJ4MeChVHYsZEMMTz0E0= UGZ9lhDLyRejxKvbulJQ9fZrUmrc$ Day 2 threat area:=20 https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt= __;!!DZ3fjg!6eLTiZTG4OPC3cyWa-B-IqOvW45tRnoWQ2sYa5GtLevFJ4MeChVHYsZEMMTz0E0= UGZ9lhDLyRejxKvbulJQ9nEQ0I4c$ Day 3 threat area:=20 https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt= __;!!DZ3fjg!6eLTiZTG4OPC3cyWa-B-IqOvW45tRnoWQ2sYa5GtLevFJ4MeChVHYsZEMMTz0E0= UGZ9lhDLyRejxKvbulJQ9Ly-OqDw$=20

=3D =3D =3D
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FOUS30 KWBC 251556
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1156 AM EDT Fri Apr 25 2025

Day 1
Valid 16Z Fri Apr 25 2025 - 12Z Sat Apr 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
NORTH TEXAS AND THE TEXAS PANHANDLE INTO SOUTHWEST OKLAHOMA...

...16Z Update...

No changes were made to the inherited ERO risk areas across the
country. The latest 12Z CAMs guidance just in have not shifted
significantly enough in any area to justify any changes, as an
ensemble of the guidance remains remarkably consistent with
previous runs, especially as compared with previous days.

This consistency may be due to the forcing, weak as it is, finally
shifting east into the Midwest and off the Plains, replacing the
previous troughing with some weak ridging. The ridging stabilizing
the upper levels through their warming is likely a contributing
factor to the lessening coverage of storms over most of the Plains.
There remains a notable convergence zone in the lower levels in the
Slight Risk area, which is why additional convection will develop
along the dry line this afternoon.

Further east, the large Marginal Risk from the Mississippi River
east is largely remnant convection with faster moving storms and
generally weaker forcing, making any stronger signals that would
favor a Slight largely nonexistent or too variable between=20
guidance to lock in on any one area.=20

Wegman

...Previous Discussion...

...Summary...
Minor adjustments were made to the Slight Risk from yesterday's Day
2 ERO area across western portions of the TX/OK Red River Valley
into the Cap Rock and Rolling Plains. Meanwhile, the Marginal Risk
area farther east was extended to include more of the Lower MS
Valley.

...North TX...Central OK...TX-OK Panhandles...Eastern NM
Slight Risk area which was hoisted yesterday in the Day 2 ERO, in
coordination with affected TX/OK offices, continues into today's
Day 1 ERO with minor modifications. Upper level flow gradually becomes
more diffluent today and tonight as the upper ridge axis pushes=20
east across the Southern Plains. Convection early this morning on=20
the leading edge of the outflow boundary south of the MCS will=20
continue to diminish south of the Red River, resulting in not much=20
rainfall from an areal-average standpoint. However, late this=20
afternoon and into the evening with the daytime heating and more=20
favorable forcing (increasing difluence aloft), additional storms=20
will develop along the dryline, likely growing upscale into an MCS=20
that will track slowly across the TX Panhandle and Red River Valley
into the overnight hours. The activity will parallel a W-E=20
oriented surface frontal boundary that will become quasi-stationary
overnight. The 00Z high-res guidance again indicated stronger=20
multicellular clusters and supercells, some of which become slow=20
moving per the simulated reflectivity guidance. Therefore there is=20
still concern that stronger storms/supercells within the MCS may=20
move more slowly or even stall, causing a more enhanced flash flood
risk, while the MCS as a whole remains over an area hard hit with=20
heavy rain in recent days. Within the Slight Risk area, the latest=20
(00Z) HREF shows highest probabilities of >5" within 12hrs (40-50+=20
percent). Meanwhile, the Slight Risk area is also supported by the=20
latest UFVS-verified CSU ERO First Guess field.

...Lower-Mid MS Valley and TN Valley to OH Valley and Lower Great
Lakes, Southern-Central Appalachians...
The Marginal Risk inherited from yesterday's Day 2 ERO was expanded
to include more of the Lower MS Valley and a little more of the Mid
Atlantic Region. Over northern areas, deep-layer instability ahead
of the cold front is largely elevated and rather meager (less than
1000 J/Kg). However given the higher relative soil moisture and
lower FFGs over these areas, embedded convective elements may cause
isolated instances of flash flooding.

Farther south across the TN Valley and towards the Gulf Coast,
instability will be more plentiful (Mixed-layer CAPEs of 1000-1500
J/Kg), while TPW values are a bit more favorable as well (between
1.5-1.7"). Despite the more favorable thermodynamic profiles, the
more transient easterly progression of the shortwave energy will
limit the duration of the heaviest rainfall. Still, more elevated
1-2"+/hr probabilities in these areas may lead to localized short-
term runoff issues.

Hurley


Day 2
Valid 12Z Sat Apr 26 2025 - 12Z Sun Apr 27 2025

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN PLAINS INTO THE SOUTHERN OZARKS AND JUST WEST OF THE
MISSISSIPPI DELTA...

...Southern Plains...
The MCS that is expected to traverse the Texas Panhandle and along
the Red River Valley Friday evening and overnight will persist
into Saturday across the Marginal Risk area. Guidance continues to
show more limited areal coverage of rain on Saturday as compared
with Friday with any additional convection that develops along the
dryline and the quasi-stationary west-to-east front. This
stationary front will eventually lift northeast as a warm front
Saturday night, taking the more organized/widespread convection
with it. Uncertainty regarding MCS behavior on Saturday remains
very high, and further updates and the move of this time frame into
CAMs range may require a later upgrade to a Slight, particularly
if heavy rain remains further west towards the Panhandle for
longer. Regardless, additional convection is likely to form again
Saturday afternoon along the dryline near the New Mexico border,
which may further worsen flooding concerns in the areas where the
storms develop.

Hurley/Wegman


Day 3
Valid 12Z Sun Apr 27 2025 - 12Z Mon Apr 28 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PARTS OF
THE GREAT BASIN AND FROM PORTIONS OF THE NORTHERN ROCKIES INTO THE
NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY...

Mid-upper trough across the southern Great Basin early Sunday will
lift across the central Rockies by 12Z Monday. This in-turn will
nudge the upper ridge axis east of the Northern Plains and Upper MS
Valley late Sunday-Sunday night, with a quick onset of upper level
divergence in its wake. Along with the more favorable dynamical
forcing (upper divergence and deep-layer ascent), deepening
southerly flow will tap the western Gulf and lead to an uptick in
low-mid layer moisture transport, with TPW values climbing to
1.25+ inches. Deep-layer instability meanwhile will also be ramping
up, to the tune of 1000-2000+ J/Kg MUCAPE per the 00Z GFS. Some of
the guidance (particularly the ECMWF) shows an MCS developing along
the western periphery of the upper ridge, then tracking east to
eventually southeast along the 850-300 mb thickness. At this point
(day 3 forecast) the forward-propagating Corfidi vectors would
support a more progressive MCS, though much will depend on the
strength of the LLJ. For now, have maintained a fairly broad
Marginal Risk area given the potential of intense short-term
(sub-3hr) rainfall rates.

Hurley


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt= __;!!DZ3fjg!9ee4-E_sVrH0LwUk8cFzdzqc5L3z0p197W2wlnpMbhIvnOfXpG4RXhcnGnls2VZ= DNYV-OUYMnnNFAAgpBjJzUaLBTdo$ Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt= __;!!DZ3fjg!9ee4-E_sVrH0LwUk8cFzdzqc5L3z0p197W2wlnpMbhIvnOfXpG4RXhcnGnls2VZ= DNYV-OUYMnnNFAAgpBjJzT0-49j0$ Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt= __;!!DZ3fjg!9ee4-E_sVrH0LwUk8cFzdzqc5L3z0p197W2wlnpMbhIvnOfXpG4RXhcnGnls2VZ= DNYV-OUYMnnNFAAgpBjJzY2fQoYQ$=20

=3D =3D =3D
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FOUS30 KWBC 251945
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
345 PM EDT Fri Apr 25 2025

Day 1
Valid 16Z Fri Apr 25 2025 - 12Z Sat Apr 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
NORTH TEXAS AND THE TEXAS PANHANDLE INTO SOUTHWEST OKLAHOMA...

...16Z Update...

No changes were made to the inherited ERO risk areas across the
country. The latest 12Z CAMs guidance just in have not shifted
significantly enough in any area to justify any changes, as an
ensemble of the guidance remains remarkably consistent with
previous runs, especially as compared with previous days.

This consistency may be due to the forcing, weak as it is, finally
shifting east into the Midwest and off the Plains, replacing the
previous troughing with some weak ridging. The ridging stabilizing
the upper levels through their warming is likely a contributing
factor to the lessening coverage of storms over most of the Plains.
There remains a notable convergence zone in the lower levels in the
Slight Risk area, which is why additional convection will develop
along the dry line this afternoon.

Further east, the large Marginal Risk from the Mississippi River
east is largely remnant convection with faster moving storms and
generally weaker forcing, making any stronger signals that would
favor a Slight largely nonexistent or too variable between
guidance to lock in on any one area.

Wegman

...Previous Discussion...

...Summary...
Minor adjustments were made to the Slight Risk from yesterday's Day
2 ERO area across western portions of the TX/OK Red River Valley
into the Cap Rock and Rolling Plains. Meanwhile, the Marginal Risk
area farther east was extended to include more of the Lower MS
Valley.

...North TX...Central OK...TX-OK Panhandles...Eastern NM
Slight Risk area which was hoisted yesterday in the Day 2 ERO, in
coordination with affected TX/OK offices, continues into today's
Day 1 ERO with minor modifications. Upper level flow gradually becomes
more diffluent today and tonight as the upper ridge axis pushes
east across the Southern Plains. Convection early this morning on
the leading edge of the outflow boundary south of the MCS will
continue to diminish south of the Red River, resulting in not much
rainfall from an areal-average standpoint. However, late this
afternoon and into the evening with the daytime heating and more
favorable forcing (increasing difluence aloft), additional storms
will develop along the dryline, likely growing upscale into an MCS
that will track slowly across the TX Panhandle and Red River Valley
into the overnight hours. The activity will parallel a W-E
oriented surface frontal boundary that will become quasi-stationary
overnight. The 00Z high-res guidance again indicated stronger
multicellular clusters and supercells, some of which become slow
moving per the simulated reflectivity guidance. Therefore there is
still concern that stronger storms/supercells within the MCS may
move more slowly or even stall, causing a more enhanced flash flood
risk, while the MCS as a whole remains over an area hard hit with
heavy rain in recent days. Within the Slight Risk area, the latest
(00Z) HREF shows highest probabilities of >5" within 12hrs (40-50+
percent). Meanwhile, the Slight Risk area is also supported by the
latest UFVS-verified CSU ERO First Guess field.

...Lower-Mid MS Valley and TN Valley to OH Valley and Lower Great
Lakes, Southern-Central Appalachians...
The Marginal Risk inherited from yesterday's Day 2 ERO was expanded
to include more of the Lower MS Valley and a little more of the Mid
Atlantic Region. Over northern areas, deep-layer instability ahead
of the cold front is largely elevated and rather meager (less than
1000 J/Kg). However given the higher relative soil moisture and
lower FFGs over these areas, embedded convective elements may cause
isolated instances of flash flooding.

Farther south across the TN Valley and towards the Gulf Coast,
instability will be more plentiful (Mixed-layer CAPEs of 1000-1500
J/Kg), while TPW values are a bit more favorable as well (between
1.5-1.7"). Despite the more favorable thermodynamic profiles, the
more transient easterly progression of the shortwave energy will
limit the duration of the heaviest rainfall. Still, more elevated
1-2"+/hr probabilities in these areas may lead to localized short-
term runoff issues.

Hurley


Day 2
Valid 12Z Sat Apr 26 2025 - 12Z Sun Apr 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHERN OKLAHOMA AND FAR NORTH TEXAS...

...20Z Update...

In coordination with OUN/Norman, OK forecast office, a Slight Risk
upgrade was introduced with this update. The flooding rains
in the Slight Risk area are expected to be from ongoing storms as
part of an overnight MCS that will be impacting the area at the=20
start of the period at 12Z/7am CDT. FFGs in the area have been
lowered from recent heavy rains along the Red River, including for
some areas as recently in the last few hours. Guidance remains in
good agreement of the development of a new MCS from dry line
convection this afternoon and evening, with the MCS persisting
through the overnight and into the morning hours before
dissipating. The good agreement with tonight's MCS stands in stark
contrast to the poor agreement of the various MCSs over the past
few days, so it lends to enough confidence between that and the
lowered FFGs along the Red River to upgrade the area to a Slight.
Elsewhere the surrounding Marginal remains largely unchanged.=20

Wegman

...Previous Discussion...

...Southern Plains...
The MCS that is expected to traverse the Texas Panhandle and along
the Red River Valley Friday evening and overnight will persist
into Saturday across the Marginal Risk area. Guidance continues to
show more limited areal coverage of rain on Saturday as compared
with Friday with any additional convection that develops along the
dryline and the quasi-stationary west-to-east front. This
stationary front will eventually lift northeast as a warm front
Saturday night, taking the more organized/widespread convection
with it. Uncertainty regarding MCS behavior on Saturday remains
very high, and further updates and the move of this time frame into
CAMs range may require a later upgrade to a Slight, particularly
if heavy rain remains further west towards the Panhandle for
longer. Regardless, additional convection is likely to form again
Saturday afternoon along the dryline near the New Mexico border,
which may further worsen flooding concerns in the areas where the
storms develop.

Hurley/Wegman


Day 3
Valid 12Z Sun Apr 27 2025 - 12Z Mon Apr 28 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PARTS OF
THE GREAT BASIN AND FROM PORTIONS OF THE NORTHERN ROCKIES INTO THE
NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY...

...20Z Update...

Very few changes were needed with the Marginal Risk areas on
D3/Sunday. Both Marginals are low-confidence, with the area of
Nevada struggling with both amounts and low snow levels, while most
of the northern Plains is relatively difficult to flood in general,
since the area is far enough from the Gulf to not have to contend
with heavy rain that often. That said, the LLJ from the Gulf will
extend that far north on Sunday, advecting in MUCAPE values=20
between 1,000 and 2,000 J/kg, so the atmospheric ingredients remain
present for storms to become strong enough to produce heavy=20
rainfall. It remains to be seen whether that rainfall will be heavy
enough to cause flooding. Given the relatively low FFGs, good=20
instability, and a constant moisture stream from the LLJ, the=20
Marginal in the area looks good.

Wegman

...Previous Discussion...

Mid-upper trough across the southern Great Basin early Sunday will
lift across the central Rockies by 12Z Monday. This in-turn will
nudge the upper ridge axis east of the Northern Plains and Upper MS
Valley late Sunday-Sunday night, with a quick onset of upper level
divergence in its wake. Along with the more favorable dynamical
forcing (upper divergence and deep-layer ascent), deepening
southerly flow will tap the western Gulf and lead to an uptick in
low-mid layer moisture transport, with TPW values climbing to
1.25+ inches. Deep-layer instability meanwhile will also be ramping
up, to the tune of 1000-2000+ J/Kg MUCAPE per the 00Z GFS. Some of
the guidance (particularly the ECMWF) shows an MCS developing along
the western periphery of the upper ridge, then tracking east to
eventually southeast along the 850-300 mb thickness. At this point
(day 3 forecast) the forward-propagating Corfidi vectors would
support a more progressive MCS, though much will depend on the
strength of the LLJ. For now, have maintained a fairly broad
Marginal Risk area given the potential of intense short-term
(sub-3hr) rainfall rates.

Hurley


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt= __;!!DZ3fjg!_16SdQZD3RKCW2JWKDBCUJOGAyUOgZZ4picUC_nUt1BKXgngbrP5z7c4pIxQPw8= UgS4XukiG6pd11T4E_VxvSeCpLPA$ Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt= __;!!DZ3fjg!_16SdQZD3RKCW2JWKDBCUJOGAyUOgZZ4picUC_nUt1BKXgngbrP5z7c4pIxQPw8= UgS4XukiG6pd11T4E_VxvprkhwbM$ Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt= __;!!DZ3fjg!_16SdQZD3RKCW2JWKDBCUJOGAyUOgZZ4picUC_nUt1BKXgngbrP5z7c4pIxQPw8= UgS4XukiG6pd11T4E_VxvZYpyy8Q$=20

=3D =3D =3D
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FOUS30 KWBC 260051
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
851 PM EDT Fri Apr 25 2025

Day 1
Valid 01Z Sat Apr 26 2025 - 12Z Sat Apr 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
NORTH TEXAS AND THE TEXAS PANHANDLE INTO SOUTHWEST OKLAHOMA...

...01Z Update...
A majority of the changes made to the Day 1 Excessive Rainfall
Outlook were based on short-term trends in satellite and radar
imagery. Expanded the southern end of the Marginal risk area in
Louisiana along a northwest-southeast convergence zone...with the
idea that upscale growth will continue for a period in response to strengthening low level flow from the Gulf. Farther
west...maintained the Marginal and Slight risk areas after
expanding and realigning the western side of each outlook category
to better match the satellite depiction.=20=20

...16Z Update...

No changes were made to the inherited ERO risk areas across the
country. The latest 12Z CAMs guidance just in have not shifted
significantly enough in any area to justify any changes, as an
ensemble of the guidance remains remarkably consistent with
previous runs, especially as compared with previous days.

This consistency may be due to the forcing, weak as it is, finally
shifting east into the Midwest and off the Plains, replacing the
previous troughing with some weak ridging. The ridging stabilizing
the upper levels through their warming is likely a contributing
factor to the lessening coverage of storms over most of the Plains.
There remains a notable convergence zone in the lower levels in the
Slight Risk area, which is why additional convection will develop
along the dry line this afternoon.

Further east, the large Marginal Risk from the Mississippi River
east is largely remnant convection with faster moving storms and
generally weaker forcing, making any stronger signals that would
favor a Slight largely nonexistent or too variable between
guidance to lock in on any one area.

Wegman

...Previous Discussion...

...Summary...
Minor adjustments were made to the Slight Risk from yesterday's Day
2 ERO area across western portions of the TX/OK Red River Valley
into the Cap Rock and Rolling Plains. Meanwhile, the Marginal Risk
area farther east was extended to include more of the Lower MS
Valley.

...North TX...Central OK...TX-OK Panhandles...Eastern NM
Slight Risk area which was hoisted yesterday in the Day 2 ERO, in
coordination with affected TX/OK offices, continues into today's
Day 1 ERO with minor modifications. Upper level flow gradually becomes
more diffluent today and tonight as the upper ridge axis pushes
east across the Southern Plains. Convection early this morning on
the leading edge of the outflow boundary south of the MCS will
continue to diminish south of the Red River, resulting in not much
rainfall from an areal-average standpoint. However, late this
afternoon and into the evening with the daytime heating and more
favorable forcing (increasing difluence aloft), additional storms
will develop along the dryline, likely growing upscale into an MCS
that will track slowly across the TX Panhandle and Red River Valley
into the overnight hours. The activity will parallel a W-E
oriented surface frontal boundary that will become quasi-stationary
overnight. The 00Z high-res guidance again indicated stronger
multicellular clusters and supercells, some of which become slow
moving per the simulated reflectivity guidance. Therefore there is
still concern that stronger storms/supercells within the MCS may
move more slowly or even stall, causing a more enhanced flash flood
risk, while the MCS as a whole remains over an area hard hit with
heavy rain in recent days. Within the Slight Risk area, the latest
(00Z) HREF shows highest probabilities of >5" within 12hrs (40-50+
percent). Meanwhile, the Slight Risk area is also supported by the
latest UFVS-verified CSU ERO First Guess field.

...Lower-Mid MS Valley and TN Valley to OH Valley and Lower Great
Lakes, Southern-Central Appalachians...
The Marginal Risk inherited from yesterday's Day 2 ERO was expanded
to include more of the Lower MS Valley and a little more of the Mid
Atlantic Region. Over northern areas, deep-layer instability ahead
of the cold front is largely elevated and rather meager (less than
1000 J/Kg). However given the higher relative soil moisture and
lower FFGs over these areas, embedded convective elements may cause
isolated instances of flash flooding.

Farther south across the TN Valley and towards the Gulf Coast,
instability will be more plentiful (Mixed-layer CAPEs of 1000-1500
J/Kg), while TPW values are a bit more favorable as well (between
1.5-1.7"). Despite the more favorable thermodynamic profiles, the
more transient easterly progression of the shortwave energy will
limit the duration of the heaviest rainfall. Still, more elevated
1-2"+/hr probabilities in these areas may lead to localized short-
term runoff issues.

Hurley


Day 2
Valid 12Z Sat Apr 26 2025 - 12Z Sun Apr 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHERN OKLAHOMA AND FAR NORTH TEXAS...

...20Z Update...

In coordination with OUN/Norman, OK forecast office, a Slight Risk
upgrade was introduced with this update. The flooding rains
in the Slight Risk area are expected to be from ongoing storms as
part of an overnight MCS that will be impacting the area at the
start of the period at 12Z/7am CDT. FFGs in the area have been
lowered from recent heavy rains along the Red River, including for
some areas as recently in the last few hours. Guidance remains in
good agreement of the development of a new MCS from dry line
convection this afternoon and evening, with the MCS persisting
through the overnight and into the morning hours before
dissipating. The good agreement with tonight's MCS stands in stark
contrast to the poor agreement of the various MCSs over the past
few days, so it lends to enough confidence between that and the
lowered FFGs along the Red River to upgrade the area to a Slight.
Elsewhere the surrounding Marginal remains largely unchanged.

Wegman

...Previous Discussion...

...Southern Plains...
The MCS that is expected to traverse the Texas Panhandle and along
the Red River Valley Friday evening and overnight will persist
into Saturday across the Marginal Risk area. Guidance continues to
show more limited areal coverage of rain on Saturday as compared
with Friday with any additional convection that develops along the
dryline and the quasi-stationary west-to-east front. This
stationary front will eventually lift northeast as a warm front
Saturday night, taking the more organized/widespread convection
with it. Uncertainty regarding MCS behavior on Saturday remains
very high, and further updates and the move of this time frame into
CAMs range may require a later upgrade to a Slight, particularly
if heavy rain remains further west towards the Panhandle for
longer. Regardless, additional convection is likely to form again
Saturday afternoon along the dryline near the New Mexico border,
which may further worsen flooding concerns in the areas where the
storms develop.

Hurley/Wegman


Day 3
Valid 12Z Sun Apr 27 2025 - 12Z Mon Apr 28 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PARTS OF
THE GREAT BASIN AND FROM PORTIONS OF THE NORTHERN ROCKIES INTO THE
NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY...

...20Z Update...

Very few changes were needed with the Marginal Risk areas on
D3/Sunday. Both Marginals are low-confidence, with the area of
Nevada struggling with both amounts and low snow levels, while most
of the northern Plains is relatively difficult to flood in general,
since the area is far enough from the Gulf to not have to contend
with heavy rain that often. That said, the LLJ from the Gulf will
extend that far north on Sunday, advecting in MUCAPE values
between 1,000 and 2,000 J/kg, so the atmospheric ingredients remain
present for storms to become strong enough to produce heavy
rainfall. It remains to be seen whether that rainfall will be heavy
enough to cause flooding. Given the relatively low FFGs, good
instability, and a constant moisture stream from the LLJ, the
Marginal in the area looks good.

Wegman

...Previous Discussion...

Mid-upper trough across the southern Great Basin early Sunday will
lift across the central Rockies by 12Z Monday. This in-turn will
nudge the upper ridge axis east of the Northern Plains and Upper MS
Valley late Sunday-Sunday night, with a quick onset of upper level
divergence in its wake. Along with the more favorable dynamical
forcing (upper divergence and deep-layer ascent), deepening
southerly flow will tap the western Gulf and lead to an uptick in
low-mid layer moisture transport, with TPW values climbing to
1.25+ inches. Deep-layer instability meanwhile will also be ramping
up, to the tune of 1000-2000+ J/Kg MUCAPE per the 00Z GFS. Some of
the guidance (particularly the ECMWF) shows an MCS developing along
the western periphery of the upper ridge, then tracking east to
eventually southeast along the 850-300 mb thickness. At this point
(day 3 forecast) the forward-propagating Corfidi vectors would
support a more progressive MCS, though much will depend on the
strength of the LLJ. For now, have maintained a fairly broad
Marginal Risk area given the potential of intense short-term
(sub-3hr) rainfall rates.

Hurley


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt= __;!!DZ3fjg!8sfVyASxDv7xm7QnWlYbXz7EtaZK55OIEj1XgYZU73qQuygZzIVYFyPFK6QLK7p= 1HHUrug8LNo0WB4BG9qas6w4Xrec$ Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt= __;!!DZ3fjg!8sfVyASxDv7xm7QnWlYbXz7EtaZK55OIEj1XgYZU73qQuygZzIVYFyPFK6QLK7p= 1HHUrug8LNo0WB4BG9qasTqyO--0$ Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt= __;!!DZ3fjg!8sfVyASxDv7xm7QnWlYbXz7EtaZK55OIEj1XgYZU73qQuygZzIVYFyPFK6QLK7p= 1HHUrug8LNo0WB4BG9qasP7OPyD8$=20

=3D =3D =3D
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FOUS30 KWBC 260829
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
429 AM EDT Sat Apr 26 2025

Day 1
Valid 12Z Sat Apr 26 2025 - 12Z Sun Apr 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
NORTH AND NORTHWEST TEXAS INTO SOUTHERN OKLAHOMA...

...Summary...
Based on the latest observational and guidance trends, have
expanded the Slight Risk from yesterday's Day 2 ERO a little=20
farther west-southwest to include a bit more of the Rolling Plains
in Northwest Texas. Otherwise, more minor adjustments were made to
the surrounding Marginal Risk area.

...Southern Plains...
MCS and resultant MCV currently traversing the Texas Panhandle=20
early this morning will gradually track ENE along the quasi-
stationary surface frontal boundary across much of the TX-OK Red=20
River Valley today. By late morning, the weakening LLJ will allow
the MCS to diminish, while later in the day (afternoon) a narrow broken
line of convection develops farther upstream along the dryline=20
across Northwest TX during peak heating. This second area of
convection is expected to take on a more ESE trek during the
afternoon and evening, thus the southwest 'bulge' to both the
Slight and Marginal Risk areas across the Rolling Plains and (for
the Marginal Risk) into northern portions of the Hill Country.=20
Overnight, the surface stationary front will eventually lift=20
northeast as a warm front Saturday night, taking the more=20 organized/widespread convection with it.=20

As with yesterday's Day 2 ERO, the Day 1 Slight Risk area was
adjusted to capture areas where 1-2+ in/hr rainfall rate probabilities
from the HREF/RRFS ensembles are highest, while also overlapping
areas where heavy rainfall has fallen over the past couple of days
(wetter antecedent interviews).=20

Hurley


Day 2
Valid 12Z Sun Apr 27 2025 - 12Z Mon Apr 28 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE NORTHERN HIGH PLAINS INTO THE UPPER MISSISSIPPI VALLEY...

Mid-upper trough across the southern Great Basin early Sunday will
lift across the central Rockies by 12Z Monday. This in-turn will=20
nudge the upper ridge axis east of the Northern Plains and Upper MS
Valley late Sunday-Sunday night, with a quick onset of upper level
divergence in its wake. Along with the more favorable dynamical=20
forcing (upper divergence and deep-layer ascent), deepening=20
southerly flow will tap the western Gulf and lead to an uptick in=20
low-mid layer moisture transport, with TPW values climbing to 1.3+=20
inches. Deep-layer instability meanwhile will also be ramping up,=20
to the tune of 1000-2000+ J/Kg MUCAPE per the 00Z models. To some=20
degree, the latest models indicate MCS development along the=20
western periphery of the upper ridge, tracking east to eventually=20
southeast along the 850-300 mb thickness. For the most part, the=20 forward-propagating Corfidi vectors would support a rather=20
progressive area of any organized convection that can grow=20
upscale, though much will depend on the strength of the LLJ. For=20
now, have maintained a fairly broad Marginal Risk area given the=20
potential of intense short-term (sub-3hr) rainfall rates.

Hurley


Day 3
Valid 12Z Mon Apr 28 2025 - 12Z Tue Apr 29 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE NORTHERN PLAINS INTO THE UPPER MIDWEST...

Mid-level circulation will open into a shortwave trough across the
northern Plains and Upper Midwest on Monday-Monday night. Ample
pre-frontal low-mid layer moisture transport and PW values climbing
to 1.5-1.75" will make for a favorable thermodynamic profile,=20
along with deep-layer instability as MUCAPEs peak between=20
2,000-3,000 J/Kg (even ~1,000 J/Kg wrapping westward into the=20
TROWAL zone). The biggest concern during this period will be with=20
cell training, especially late Monday-Monday night across the Upper
Midwest with the strengthening LLJ and weakening downwind Corfidi=20
Vectors. For now, guidance spread with the heavier QPF is still=20
rather high (not well consolidated to support a Slight Risk at=20
this point). However, per the GFS/ECMWF and especially the GEM-=20
Regional, localized totals of 3-5+ inches within 12 hours would=20
appear likely in this setup.

Hurley


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt= __;!!DZ3fjg!-UcQBTn_0liMEHHvybboXdRWUsQ9jVteIXIw5vkWMoIVuT14zrH86VbtiVNEw0c= 9aQA8Mkfnx0ONz1shgx-mvd6yZFM$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt= __;!!DZ3fjg!-UcQBTn_0liMEHHvybboXdRWUsQ9jVteIXIw5vkWMoIVuT14zrH86VbtiVNEw0c= 9aQA8Mkfnx0ONz1shgx-mxaARNtQ$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt= __;!!DZ3fjg!-UcQBTn_0liMEHHvybboXdRWUsQ9jVteIXIw5vkWMoIVuT14zrH86VbtiVNEw0c= 9aQA8Mkfnx0ONz1shgx-mdLb_zV8$=20

=3D =3D =3D
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FOUS30 KWBC 261552
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1152 AM EDT Sat Apr 26 2025

Day 1
Valid 16Z Sat Apr 26 2025 - 12Z Sun Apr 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
NORTH AND NORTHWEST TEXAS INTO SOUTHERN OKLAHOMA...

...16Z Update...

The Slight Risk area was adjusted downstream of the ongoing
convection occurring across far north Texas and central and
southern Oklahoma. A well established Mesoscale Convective Vortex
is approaching the Oklahoma City area as of the time of this
writing, with training thunderstorms actively causing flash
flooding south of the city. For that reason, a higher-end Slight=20
is in effect roughly from the Oklahoma City south to the Texas
state line along the I-35 corridor, extending west to about=20
Wichita Falls, TX.

Guidance is in understandably reasonable agreement that this MCS
will persist over the next few hours, as the embedded MCV tracks
along I-44. For now, the slow movement and lack of instability
suggests metro Tulsa only has an isolated (and therefore, Marginal)
flash flooding threat.

The Slight and surrounding Marginal were trimmed on the
northwestern side behind the MCS, as none of the guidance suggests
that there will be afternoon convection in this area with all the
instability having been used up. The Marginal is largely unchanged
owing to poor agreement in the CAMs as to how new convection will
emerge this afternoon across portions of central and northern
Texas. The behavior of the MCS as a whole will play a big role in
how any new convection develops this afternoon.

Wegman

...Previous Discussion...

...Summary...
Based on the latest observational and guidance trends, have
expanded the Slight Risk from yesterday's Day 2 ERO a little
farther west-southwest to include a bit more of the Rolling Plains
in Northwest Texas. Otherwise, more minor adjustments were made to
the surrounding Marginal Risk area.

...Southern Plains...
MCS and resultant MCV currently traversing the Texas Panhandle
early this morning will gradually track ENE along the quasi-
stationary surface frontal boundary across much of the TX-OK Red
River Valley today. By late morning, the weakening LLJ will allow
the MCS to diminish, while later in the day (afternoon) a narrow broken
line of convection develops farther upstream along the dryline
across Northwest TX during peak heating. This second area of
convection is expected to take on a more ESE trek during the
afternoon and evening, thus the southwest 'bulge' to both the
Slight and Marginal Risk areas across the Rolling Plains and (for
the Marginal Risk) into northern portions of the Hill Country.
Overnight, the surface stationary front will eventually lift
northeast as a warm front Saturday night, taking the more
organized/widespread convection with it.

As with yesterday's Day 2 ERO, the Day 1 Slight Risk area was
adjusted to capture areas where 1-2+ in/hr rainfall rate probabilities
from the HREF/RRFS ensembles are highest, while also overlapping
areas where heavy rainfall has fallen over the past couple of days
(wetter antecedent interviews).

Hurley


Day 2
Valid 12Z Sun Apr 27 2025 - 12Z Mon Apr 28 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE NORTHERN HIGH PLAINS INTO THE UPPER MISSISSIPPI VALLEY...

Mid-upper trough across the southern Great Basin early Sunday will
lift across the central Rockies by 12Z Monday. This in-turn will
nudge the upper ridge axis east of the Northern Plains and Upper MS
Valley late Sunday-Sunday night, with a quick onset of upper level
divergence in its wake. Along with the more favorable dynamical
forcing (upper divergence and deep-layer ascent), deepening
southerly flow will tap the western Gulf and lead to an uptick in
low-mid layer moisture transport, with TPW values climbing to 1.3+
inches. Deep-layer instability meanwhile will also be ramping up,
to the tune of 1000-2000+ J/Kg MUCAPE per the 00Z models. To some
degree, the latest models indicate MCS development along the
western periphery of the upper ridge, tracking east to eventually
southeast along the 850-300 mb thickness. For the most part, the forward-propagating Corfidi vectors would support a rather
progressive area of any organized convection that can grow
upscale, though much will depend on the strength of the LLJ. For
now, have maintained a fairly broad Marginal Risk area given the
potential of intense short-term (sub-3hr) rainfall rates.

Hurley


Day 3
Valid 12Z Mon Apr 28 2025 - 12Z Tue Apr 29 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE NORTHERN PLAINS INTO THE UPPER MIDWEST...

Mid-level circulation will open into a shortwave trough across the
northern Plains and Upper Midwest on Monday-Monday night. Ample
pre-frontal low-mid layer moisture transport and PW values climbing
to 1.5-1.75" will make for a favorable thermodynamic profile,
along with deep-layer instability as MUCAPEs peak between
2,000-3,000 J/Kg (even ~1,000 J/Kg wrapping westward into the
TROWAL zone). The biggest concern during this period will be with
cell training, especially late Monday-Monday night across the Upper
Midwest with the strengthening LLJ and weakening downwind Corfidi
Vectors. For now, guidance spread with the heavier QPF is still
rather high (not well consolidated to support a Slight Risk at
this point). However, per the GFS/ECMWF and especially the GEM-
Regional, localized totals of 3-5+ inches within 12 hours would
appear likely in this setup.

Hurley


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt= __;!!DZ3fjg!8xo5XMP1C5b29IAfNXn6FPGNwfPvMLZa7RQsgy1yeeTeTndYyRpZvNy-8ug6hlu= uAN_RFEvmTTj0GQK2LcaJHpCdSgw$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt= __;!!DZ3fjg!8xo5XMP1C5b29IAfNXn6FPGNwfPvMLZa7RQsgy1yeeTeTndYyRpZvNy-8ug6hlu= uAN_RFEvmTTj0GQK2LcaJcQaVrmY$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt= __;!!DZ3fjg!8xo5XMP1C5b29IAfNXn6FPGNwfPvMLZa7RQsgy1yeeTeTndYyRpZvNy-8ug6hlu= uAN_RFEvmTTj0GQK2LcaJrLUgsJs$=20

=3D =3D =3D
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FOUS30 KWBC 261900
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
300 PM EDT Sat Apr 26 2025

Day 1
Valid 16Z Sat Apr 26 2025 - 12Z Sun Apr 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
NORTH AND NORTHWEST TEXAS INTO SOUTHERN OKLAHOMA...

...16Z Update...

The Slight Risk area was adjusted downstream of the ongoing
convection occurring across far north Texas and central and
southern Oklahoma. A well established Mesoscale Convective Vortex
is approaching the Oklahoma City area as of the time of this
writing, with training thunderstorms actively causing flash
flooding south of the city. For that reason, a higher-end Slight
is in effect roughly from the Oklahoma City south to the Texas
state line along the I-35 corridor, extending west to about
Wichita Falls, TX.

Guidance is in understandably reasonable agreement that this MCS
will persist over the next few hours, as the embedded MCV tracks
along I-44. For now, the slow movement and lack of instability
suggests metro Tulsa only has an isolated (and therefore, Marginal)
flash flooding threat.

The Slight and surrounding Marginal were trimmed on the
northwestern side behind the MCS, as none of the guidance suggests
that there will be afternoon convection in this area with all the
instability having been used up. The Marginal is largely unchanged
owing to poor agreement in the CAMs as to how new convection will
emerge this afternoon across portions of central and northern
Texas. The behavior of the MCS as a whole will play a big role in
how any new convection develops this afternoon.

Wegman

...Previous Discussion...

...Summary...
Based on the latest observational and guidance trends, have
expanded the Slight Risk from yesterday's Day 2 ERO a little
farther west-southwest to include a bit more of the Rolling Plains
in Northwest Texas. Otherwise, more minor adjustments were made to
the surrounding Marginal Risk area.

...Southern Plains...
MCS and resultant MCV currently traversing the Texas Panhandle
early this morning will gradually track ENE along the quasi-
stationary surface frontal boundary across much of the TX-OK Red
River Valley today. By late morning, the weakening LLJ will allow
the MCS to diminish, while later in the day (afternoon) a narrow broken
line of convection develops farther upstream along the dryline
across Northwest TX during peak heating. This second area of
convection is expected to take on a more ESE trek during the
afternoon and evening, thus the southwest 'bulge' to both the
Slight and Marginal Risk areas across the Rolling Plains and (for
the Marginal Risk) into northern portions of the Hill Country.
Overnight, the surface stationary front will eventually lift
northeast as a warm front Saturday night, taking the more
organized/widespread convection with it.

As with yesterday's Day 2 ERO, the Day 1 Slight Risk area was
adjusted to capture areas where 1-2+ in/hr rainfall rate probabilities
from the HREF/RRFS ensembles are highest, while also overlapping
areas where heavy rainfall has fallen over the past couple of days
(wetter antecedent interviews).

Hurley


Day 2
Valid 12Z Sun Apr 27 2025 - 12Z Mon Apr 28 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHERN AND SOUTHEASTERN MONTANA...

...1930Z Update...

In coordination with BYZ/Billings, MT forecast office, a Slight
Risk upgrade was introduced with this update. Increasing forecast
rainfall (areal averages of 2-3 inches southwest of Billings) will
combine with high snow levels and burn scars to locally enhance the
flash flooding potential in this area of Montana. The combination
of surface troughing ahead of a northward moving leeside low out of
Colorado, an advancing upper level low and trough out of the
Rockies, and the northern tongue of an LLJ that originates straight
out of the Gulf will all combine their respective forcings to
support the area of heavy rain across southern Montana Sunday and
Sunday night. High snow levels will support rain falling on snow,
locally increasing snowmelt. Burn scars from various large fires
last year will also locally increase the flash flooding potential=20
due to locally enhanced runoff. FFGs in portions of the Slight=20
Risk area are under an inch per hour, which are rates that are=20
probable to be exceeded given the convergence of all the=20
aforementioned ingredients favoring heavy rainfall. Widely=20
scattered instances of flash flooding are likely.=20

Wegman

...Previous Discussion...

Mid-upper trough across the southern Great Basin early Sunday will
lift across the central Rockies by 12Z Monday. This in-turn will
nudge the upper ridge axis east of the Northern Plains and Upper MS
Valley late Sunday-Sunday night, with a quick onset of upper level
divergence in its wake. Along with the more favorable dynamical
forcing (upper divergence and deep-layer ascent), deepening
southerly flow will tap the western Gulf and lead to an uptick in
low-mid layer moisture transport, with TPW values climbing to 1.3+
inches. Deep-layer instability meanwhile will also be ramping up,
to the tune of 1000-2000+ J/Kg MUCAPE per the 00Z models. To some
degree, the latest models indicate MCS development along the
western periphery of the upper ridge, tracking east to eventually
southeast along the 850-300 mb thickness. For the most part, the forward-propagating Corfidi vectors would support a rather
progressive area of any organized convection that can grow
upscale, though much will depend on the strength of the LLJ. For
now, have maintained a fairly broad Marginal Risk area given the
potential of intense short-term (sub-3hr) rainfall rates.

Hurley


Day 3
Valid 12Z Mon Apr 28 2025 - 12Z Tue Apr 29 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE NORTHERN PLAINS INTO THE UPPER MIDWEST...

...1930Z Update...

No significant changes were needed for the Marginal Risk area
across the northern Plains and upper Midwest. Deep soils across the
Dakotas and prevalence of lakes in northern Minnesota should
largely preclude other than isolated flash flooding. The cold=20
conveyor belt of an intensifying low will run into a strong cold=20
front with deep cold air behind it, resulting in ample baroclinic
forcing for steady light to moderate rain across the Dakotas and
Minnesota. Meanwhile into Wisconsin the pre-cold frontal convection
will be the driver for any isolated flash flooding.

There is some potential that before snow levels crash in
southeastern Montana that lingering rainfall from Sunday night may
continue into Monday. This may resulting in a locally enhanced=20
flash flooding risk into far northern Wyoming with the burn scars=20
on the northwest facing slopes of the Bighorn Mountains. The=20
predominant northeasterly flow orthogonal to the range may locally=20
enhance upslope and heavy rainfall rates in the area.=20

Wegman

...Previous Discussion...

Mid-level circulation will open into a shortwave trough across the
northern Plains and Upper Midwest on Monday-Monday night. Ample
pre-frontal low-mid layer moisture transport and PW values climbing
to 1.5-1.75" will make for a favorable thermodynamic profile,
along with deep-layer instability as MUCAPEs peak between
2,000-3,000 J/Kg (even ~1,000 J/Kg wrapping westward into the
TROWAL zone). The biggest concern during this period will be with
cell training, especially late Monday-Monday night across the Upper
Midwest with the strengthening LLJ and weakening downwind Corfidi
Vectors. For now, guidance spread with the heavier QPF is still
rather high (not well consolidated to support a Slight Risk at
this point). However, per the GFS/ECMWF and especially the GEM-
Regional, localized totals of 3-5+ inches within 12 hours would
appear likely in this setup.

Hurley


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt= __;!!DZ3fjg!_pyAgUFxwdnO3O47BgPhtqFIwaC-Mqz7SuiqjMIC0QbmIsBnCwZJzf7xiXJY_fQ= 3Nx_G_Bwg4XlzpqDlVpc6kPi5yZM$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt= __;!!DZ3fjg!_pyAgUFxwdnO3O47BgPhtqFIwaC-Mqz7SuiqjMIC0QbmIsBnCwZJzf7xiXJY_fQ= 3Nx_G_Bwg4XlzpqDlVpc6Ma_7tAY$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt= __;!!DZ3fjg!_pyAgUFxwdnO3O47BgPhtqFIwaC-Mqz7SuiqjMIC0QbmIsBnCwZJzf7xiXJY_fQ= 3Nx_G_Bwg4XlzpqDlVpc6hYK5QUI$=20

=3D =3D =3D
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FOUS30 KWBC 270052
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
852 PM EDT Sat Apr 26 2025

Day 1
Valid 01Z Sun Apr 27 2025 - 12Z Sun Apr 27 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR A SMALL
PORTION OF WEST TEXAS...

...01Z Update...
Introduced a Marginal Risk area over portions of West Texas where
isolated supercells formed earlier in the afternoon and were
progressing eastward into parts of West Texas. Given the
progressive nature of convection and the fact the convection will
be encountering more stable airmass later...there are some factors
working against excessive rainfall. Until then...low level flow
will draw instability/low level moisture into the inflow region of
the storm with rainfall rates of 1.5 to 1.8 inches per hour being
possible. Rainfall rates that high...even over a fairly short
duration...has the potential to produce isolated instances of
flash flooding especially in areas of poor drainage or in an urban
area.

Bann

...16Z Update...

The Slight Risk area was adjusted downstream of the ongoing
convection occurring across far north Texas and central and
southern Oklahoma. A well established Mesoscale Convective Vortex
is approaching the Oklahoma City area as of the time of this
writing, with training thunderstorms actively causing flash
flooding south of the city. For that reason, a higher-end Slight
is in effect roughly from the Oklahoma City south to the Texas
state line along the I-35 corridor, extending west to about
Wichita Falls, TX.

Guidance is in understandably reasonable agreement that this MCS
will persist over the next few hours, as the embedded MCV tracks
along I-44. For now, the slow movement and lack of instability
suggests metro Tulsa only has an isolated (and therefore, Marginal)
flash flooding threat.

The Slight and surrounding Marginal were trimmed on the
northwestern side behind the MCS, as none of the guidance suggests
that there will be afternoon convection in this area with all the
instability having been used up. The Marginal is largely unchanged
owing to poor agreement in the CAMs as to how new convection will
emerge this afternoon across portions of central and northern
Texas. The behavior of the MCS as a whole will play a big role in
how any new convection develops this afternoon.

Wegman

...Previous Discussion...

...Summary...
Based on the latest observational and guidance trends, have
expanded the Slight Risk from yesterday's Day 2 ERO a little
farther west-southwest to include a bit more of the Rolling Plains
in Northwest Texas. Otherwise, more minor adjustments were made to
the surrounding Marginal Risk area.

...Southern Plains...
MCS and resultant MCV currently traversing the Texas Panhandle
early this morning will gradually track ENE along the quasi-
stationary surface frontal boundary across much of the TX-OK Red
River Valley today. By late morning, the weakening LLJ will allow
the MCS to diminish, while later in the day (afternoon) a narrow broken
line of convection develops farther upstream along the dryline
across Northwest TX during peak heating. This second area of
convection is expected to take on a more ESE trek during the
afternoon and evening, thus the southwest 'bulge' to both the
Slight and Marginal Risk areas across the Rolling Plains and (for
the Marginal Risk) into northern portions of the Hill Country.
Overnight, the surface stationary front will eventually lift
northeast as a warm front Saturday night, taking the more
organized/widespread convection with it.

As with yesterday's Day 2 ERO, the Day 1 Slight Risk area was
adjusted to capture areas where 1-2+ in/hr rainfall rate probabilities
from the HREF/RRFS ensembles are highest, while also overlapping
areas where heavy rainfall has fallen over the past couple of days
(wetter antecedent interviews).

Hurley


Day 2
Valid 12Z Sun Apr 27 2025 - 12Z Mon Apr 28 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHERN AND SOUTHEASTERN MONTANA...

...1930Z Update...

In coordination with BYZ/Billings, MT forecast office, a Slight
Risk upgrade was introduced with this update. Increasing forecast
rainfall (areal averages of 2-3 inches southwest of Billings) will
combine with high snow levels and burn scars to locally enhance the
flash flooding potential in this area of Montana. The combination
of surface troughing ahead of a northward moving leeside low out of
Colorado, an advancing upper level low and trough out of the
Rockies, and the northern tongue of an LLJ that originates straight
out of the Gulf will all combine their respective forcings to
support the area of heavy rain across southern Montana Sunday and
Sunday night. High snow levels will support rain falling on snow,
locally increasing snowmelt. Burn scars from various large fires
last year will also locally increase the flash flooding potential
due to locally enhanced runoff. FFGs in portions of the Slight
Risk area are under an inch per hour, which are rates that are
probable to be exceeded given the convergence of all the
aforementioned ingredients favoring heavy rainfall. Widely
scattered instances of flash flooding are likely.

Wegman

...Previous Discussion...

Mid-upper trough across the southern Great Basin early Sunday will
lift across the central Rockies by 12Z Monday. This in-turn will
nudge the upper ridge axis east of the Northern Plains and Upper MS
Valley late Sunday-Sunday night, with a quick onset of upper level
divergence in its wake. Along with the more favorable dynamical
forcing (upper divergence and deep-layer ascent), deepening
southerly flow will tap the western Gulf and lead to an uptick in
low-mid layer moisture transport, with TPW values climbing to 1.3+
inches. Deep-layer instability meanwhile will also be ramping up,
to the tune of 1000-2000+ J/Kg MUCAPE per the 00Z models. To some
degree, the latest models indicate MCS development along the
western periphery of the upper ridge, tracking east to eventually
southeast along the 850-300 mb thickness. For the most part, the forward-propagating Corfidi vectors would support a rather
progressive area of any organized convection that can grow
upscale, though much will depend on the strength of the LLJ. For
now, have maintained a fairly broad Marginal Risk area given the
potential of intense short-term (sub-3hr) rainfall rates.

Hurley


Day 3
Valid 12Z Mon Apr 28 2025 - 12Z Tue Apr 29 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE NORTHERN PLAINS INTO THE UPPER MIDWEST...

...1930Z Update...

No significant changes were needed for the Marginal Risk area
across the northern Plains and upper Midwest. Deep soils across the
Dakotas and prevalence of lakes in northern Minnesota should
largely preclude other than isolated flash flooding. The cold
conveyor belt of an intensifying low will run into a strong cold
front with deep cold air behind it, resulting in ample baroclinic
forcing for steady light to moderate rain across the Dakotas and
Minnesota. Meanwhile into Wisconsin the pre-cold frontal convection
will be the driver for any isolated flash flooding.

There is some potential that before snow levels crash in
southeastern Montana that lingering rainfall from Sunday night may
continue into Monday. This may resulting in a locally enhanced
flash flooding risk into far northern Wyoming with the burn scars
on the northwest facing slopes of the Bighorn Mountains. The
predominant northeasterly flow orthogonal to the range may locally
enhance upslope and heavy rainfall rates in the area.

Wegman

...Previous Discussion...

Mid-level circulation will open into a shortwave trough across the
northern Plains and Upper Midwest on Monday-Monday night. Ample
pre-frontal low-mid layer moisture transport and PW values climbing
to 1.5-1.75" will make for a favorable thermodynamic profile,
along with deep-layer instability as MUCAPEs peak between
2,000-3,000 J/Kg (even ~1,000 J/Kg wrapping westward into the
TROWAL zone). The biggest concern during this period will be with
cell training, especially late Monday-Monday night across the Upper
Midwest with the strengthening LLJ and weakening downwind Corfidi
Vectors. For now, guidance spread with the heavier QPF is still
rather high (not well consolidated to support a Slight Risk at
this point). However, per the GFS/ECMWF and especially the GEM-
Regional, localized totals of 3-5+ inches within 12 hours would
appear likely in this setup.

Hurley


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt= __;!!DZ3fjg!7JmZsM_ziMDaFJHsv3VA21jPiA52cVJyMsvy-EwExX2xngiyJLvHk3Fe0EkTuc9= ibaw7afNhIVkBrNiZH67m5mC0XoM$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt= __;!!DZ3fjg!7JmZsM_ziMDaFJHsv3VA21jPiA52cVJyMsvy-EwExX2xngiyJLvHk3Fe0EkTuc9= ibaw7afNhIVkBrNiZH67mhZT8o3Y$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt= __;!!DZ3fjg!7JmZsM_ziMDaFJHsv3VA21jPiA52cVJyMsvy-EwExX2xngiyJLvHk3Fe0EkTuc9= ibaw7afNhIVkBrNiZH67mXTg2HOE$=20

=3D =3D =3D
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FOUS30 KWBC 270830
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
430 AM EDT Sun Apr 27 2025

Day 1
Valid 12Z Sun Apr 27 2025 - 12Z Mon Apr 28 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTH-CENTRAL AND SOUTHEASTERN MONTANA...

...Summary...
Minimal modifications were made to the Slight and Marginal Risk
areas from yesterday's Day 2 ERO.=20

...Northern High Plains to the Mid Mississippi Valley...
Mid-Upper low migrating across the central Great Basin-central
Rockies during the period will set the stage for robust deep-layer
forcing over the outlook areas as the upper ridge axis moves east.
Helping matters will be coupled upper level jet streaks, i.e. with
the ribbon of enhanced lift within the right-entrance region of the
upper jet streak traversing south-central Canada, while also=20
within the left-exit region of the upper jet streak lifting into=20
the Front Range and Central Plains. Robust low-mid level moisture=20
transport turning westward into the maturing Cold Conveyor Belt=20
(CCB) and maturing TROWAL will reach 2-3 standard deviations above=20
normal across the Northern Plains per the 00Z GEFS, while=20
anomalies peak between +3 and +5 across the Upper MS Valley Sunday=20
night. This as the south-southwesterly LLJ peaks by Sunday night=20
(~50 kts at 850 mb), while strengthening ENE-NE low-level flow=20
peaking between 30-40 kts across the backside of the CCB will lead=20
to a considerable upslope component to the lift across the=20
foothills and High Plains of south-central and southeast MT into=20
northeast WY.=20

The Slight Risk area was largely unchanged. Peak rainfall totals of
2-4+" west and southwest of Billings will combine with high snow=20
levels and burn scars to locally enhance the flash flooding=20
potential in this area of Montana. Farther east across the northern
Plains and Upper MS Valley, deep-layer instability will become more
plentiful (MUCAPEs peaking aoa 1,000 J/Kg), while the low-level
moisture transport becomes more robust Sunday night given the
aforementioned uptick in the LLJ. Despite the more favorable deep-
layer thermodynamical profile, the spread in the model QPFs is much
higher over this area, particularly with the heavier rainfall. This
is likely to the more transient (less persistent), mainly WAA-
driven upper level forcing, along with the low-level fronts=20
remaining upstream of the Upper MS Valley through Sunday night. In
addition, the forward-propagating Corfidi vectors would support a=20
rather progressive motion of any organized convection that is able
to grow upscale. As a result, the Marginal Risk area was=20
maintained across the lower (Northern) Plains and Upper MS Valley.=20

Hurley


Day 2
Valid 12Z Mon Apr 28 2025 - 12Z Tue Apr 29 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE NORTHERN PLAINS INTO THE UPPER MIDWEST...

...Summary...
Based on the favorable deep-layer synoptic forcing and
thermodynamic profile and the uptick in areal-average model QPFs
(especially the upper-bound totals), have hoisted a fairly large
Slight Risk area across parts of the Northern Plains and Upper=20
Midwest. Also expanded the Marginal Risk area across SD, southwest
MN, and Iowa from yesterday's Day 2 ERO.

Mid-level circulation will open into a shortwave trough across the
northern Plains and Upper Midwest on Monday-Monday night. Ample
pre-frontal low-mid layer moisture transport and PW values climbing
to 1.5-1.75" will make for a favorable thermodynamic profile,
along with deep-layer instability as MUCAPEs peak between
2,000-3,000 J/Kg (even ~1,000 J/Kg wrapping westward into the
TROWAL zone). The biggest concern during this period will be with
cell training, especially late Monday-Monday night across the Upper
Midwest with the strengthening LLJ (50-55 kt at 850 mb) and=20
weakening downwind Corfidi Vectors. The 00Z guidance has become a
bit more clustered with the heaviest QPF within the Slight Risk
area, with pockets of 3-5+ inches per the higher-resolution models.=20

Hurley


Day 3
Valid 12Z Tue Apr 29 2025 - 12Z Wed Apr 30 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE SOUTHERN PLAINS INTO THE OZARKS AND LOWER MISSOURI VALLEY...

Another potential significant rainfall event will be taking shape
across western portions of the TX-OK Red River Valley northeast
into the Ozarks and Lower MO River Valley. This as the upper trough
west/ridge east amplify and in-turn exhibit slower W-E=20
progression. This will allow for a more prolonged period of=20
favorable upper level forcing (coupled southern and northern stream
jet streaks) along a surface front that will become quasi-
stationary across OK- southeast KS into central MO. Robust=20
synoptic-scale forcing, favorable thermodynamic profiles (Mixed=20
Layer CAPEs 1000-2000 J/Kg and TPWs 1.5-1.75") and the the enhanced
risk of repetitive convection along the slow moving/stalled=20
frontal boundary will likely lead to impressive 24 hr rainfall=20
totals within the Slight Risk area (3-5+ inches, with higher=20
localized totals per the higher-resolution GEM-Region and RRFS=20
runs). Tuesday night in particular may bring a more enhanced flash=20
flood threat, as the LLJ veers and becomes nearly parallel (and of=20
similar magnitude of) the mean 850-300 mb flow, thereby leading to=20
weaker forward-propagating Corfidi Vectors and allowing for a=20
greater risk of cell training.

Hurley

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt= __;!!DZ3fjg!-YV-Osn7kpJbEUA8CxKFxftGEp0Fa_H94EIdV2UeGxunGNCAemzNF4F3DrmxLB_= YzAVU6tJ8R7srsIXFlFwrwCIfBss$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt= __;!!DZ3fjg!-YV-Osn7kpJbEUA8CxKFxftGEp0Fa_H94EIdV2UeGxunGNCAemzNF4F3DrmxLB_= YzAVU6tJ8R7srsIXFlFwrMxjaAD4$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt= __;!!DZ3fjg!-YV-Osn7kpJbEUA8CxKFxftGEp0Fa_H94EIdV2UeGxunGNCAemzNF4F3DrmxLB_= YzAVU6tJ8R7srsIXFlFwr79hsBug$=20

=3D =3D =3D
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FOUS30 KWBC 271535
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1135 AM EDT Sun Apr 27 2025

Day 1
Valid 16Z Sun Apr 27 2025 - 12Z Mon Apr 28 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTH-CENTRAL AND SOUTHEASTERN MONTANA...

...16Z Update...

Very few changes were needed to the outlook areas with this update.
Guidance remains largely on track, with the Slight Risk across
south-central and southeastern Montana remaining in place.=20
Moderate rainfall rates up to an inch per hour (heavy in upslope=20
areas) will combine with snowmelt and burn scars to locally
increase the coverage of instances of flash flooding to widely
scattered. Most of the event will occur tonight, continuing in some
areas into Monday morning.=20

Southeastern portions of the Marginal were trimmed over Minnesota,
Iowa, and South Dakota with the latest guidance shifting the
potential for training thunderstorms north and west.=20


Wegman

...Previous Discussion...

...Summary...
Minimal modifications were made to the Slight and Marginal Risk
areas from yesterday's Day 2 ERO.

...Northern High Plains to the Mid Mississippi Valley...
Mid-Upper low migrating across the central Great Basin-central
Rockies during the period will set the stage for robust deep-layer
forcing over the outlook areas as the upper ridge axis moves east.
Helping matters will be coupled upper level jet streaks, i.e. with
the ribbon of enhanced lift within the right-entrance region of the
upper jet streak traversing south-central Canada, while also
within the left-exit region of the upper jet streak lifting into
the Front Range and Central Plains. Robust low-mid level moisture
transport turning westward into the maturing Cold Conveyor Belt
(CCB) and maturing TROWAL will reach 2-3 standard deviations above
normal across the Northern Plains per the 00Z GEFS, while
anomalies peak between +3 and +5 across the Upper MS Valley Sunday
night. This as the south-southwesterly LLJ peaks by Sunday night
(~50 kts at 850 mb), while strengthening ENE-NE low-level flow
peaking between 30-40 kts across the backside of the CCB will lead
to a considerable upslope component to the lift across the
foothills and High Plains of south-central and southeast MT into
northeast WY.

The Slight Risk area was largely unchanged. Peak rainfall totals of
2-4+" west and southwest of Billings will combine with high snow
levels and burn scars to locally enhance the flash flooding
potential in this area of Montana. Farther east across the northern
Plains and Upper MS Valley, deep-layer instability will become more
plentiful (MUCAPEs peaking aoa 1,000 J/Kg), while the low-level
moisture transport becomes more robust Sunday night given the
aforementioned uptick in the LLJ. Despite the more favorable deep-
layer thermodynamical profile, the spread in the model QPFs is much
higher over this area, particularly with the heavier rainfall. This
is likely to the more transient (less persistent), mainly WAA-
driven upper level forcing, along with the low-level fronts
remaining upstream of the Upper MS Valley through Sunday night. In
addition, the forward-propagating Corfidi vectors would support a
rather progressive motion of any organized convection that is able
to grow upscale. As a result, the Marginal Risk area was
maintained across the lower (Northern) Plains and Upper MS Valley.

Hurley


Day 2
Valid 12Z Mon Apr 28 2025 - 12Z Tue Apr 29 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE NORTHERN PLAINS INTO THE UPPER MIDWEST...

...Summary...
Based on the favorable deep-layer synoptic forcing and
thermodynamic profile and the uptick in areal-average model QPFs
(especially the upper-bound totals), have hoisted a fairly large
Slight Risk area across parts of the Northern Plains and Upper
Midwest. Also expanded the Marginal Risk area across SD, southwest
MN, and Iowa from yesterday's Day 2 ERO.

Mid-level circulation will open into a shortwave trough across the
northern Plains and Upper Midwest on Monday-Monday night. Ample
pre-frontal low-mid layer moisture transport and PW values climbing
to 1.5-1.75" will make for a favorable thermodynamic profile,
along with deep-layer instability as MUCAPEs peak between
2,000-3,000 J/Kg (even ~1,000 J/Kg wrapping westward into the
TROWAL zone). The biggest concern during this period will be with
cell training, especially late Monday-Monday night across the Upper
Midwest with the strengthening LLJ (50-55 kt at 850 mb) and
weakening downwind Corfidi Vectors. The 00Z guidance has become a
bit more clustered with the heaviest QPF within the Slight Risk
area, with pockets of 3-5+ inches per the higher-resolution models.

Hurley


Day 3
Valid 12Z Tue Apr 29 2025 - 12Z Wed Apr 30 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE SOUTHERN PLAINS INTO THE OZARKS AND LOWER MISSOURI VALLEY...

Another potential significant rainfall event will be taking shape
across western portions of the TX-OK Red River Valley northeast
into the Ozarks and Lower MO River Valley. This as the upper trough
west/ridge east amplify and in-turn exhibit slower W-E
progression. This will allow for a more prolonged period of
favorable upper level forcing (coupled southern and northern stream
jet streaks) along a surface front that will become quasi-
stationary across OK- southeast KS into central MO. Robust
synoptic-scale forcing, favorable thermodynamic profiles (Mixed
Layer CAPEs 1000-2000 J/Kg and TPWs 1.5-1.75") and the the enhanced
risk of repetitive convection along the slow moving/stalled
frontal boundary will likely lead to impressive 24 hr rainfall
totals within the Slight Risk area (3-5+ inches, with higher
localized totals per the higher-resolution GEM-Region and RRFS
runs). Tuesday night in particular may bring a more enhanced flash
flood threat, as the LLJ veers and becomes nearly parallel (and of
similar magnitude of) the mean 850-300 mb flow, thereby leading to
weaker forward-propagating Corfidi Vectors and allowing for a
greater risk of cell training.

Hurley

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt= __;!!DZ3fjg!9NOn9KboixnxaNzaKZu4V1mxwpx5W186AQwejzt_8lbxDFRzT295qMlvZn5L9Uy= 1msQjOAJiqk1sOZ_mJf1hUZtH0N8$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt= __;!!DZ3fjg!9NOn9KboixnxaNzaKZu4V1mxwpx5W186AQwejzt_8lbxDFRzT295qMlvZn5L9Uy= 1msQjOAJiqk1sOZ_mJf1hmr3km_4$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt= __;!!DZ3fjg!9NOn9KboixnxaNzaKZu4V1mxwpx5W186AQwejzt_8lbxDFRzT295qMlvZn5L9Uy= 1msQjOAJiqk1sOZ_mJf1hzOqfKMQ$=20

=3D =3D =3D
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FOUS30 KWBC 271947
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
347 PM EDT Sun Apr 27 2025

Day 1
Valid 16Z Sun Apr 27 2025 - 12Z Mon Apr 28 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTH-CENTRAL AND SOUTHEASTERN MONTANA...

...16Z Update...

Very few changes were needed to the outlook areas with this update.
Guidance remains largely on track, with the Slight Risk across
south-central and southeastern Montana remaining in place.
Moderate rainfall rates up to an inch per hour (heavy in upslope
areas) will combine with snowmelt and burn scars to locally
increase the coverage of instances of flash flooding to widely
scattered. Most of the event will occur tonight, continuing in some
areas into Monday morning.

Southeastern portions of the Marginal were trimmed over Minnesota,
Iowa, and South Dakota with the latest guidance shifting the
potential for training thunderstorms north and west.


Wegman

...Previous Discussion...

...Summary...
Minimal modifications were made to the Slight and Marginal Risk
areas from yesterday's Day 2 ERO.

...Northern High Plains to the Mid Mississippi Valley...
Mid-Upper low migrating across the central Great Basin-central
Rockies during the period will set the stage for robust deep-layer
forcing over the outlook areas as the upper ridge axis moves east.
Helping matters will be coupled upper level jet streaks, i.e. with
the ribbon of enhanced lift within the right-entrance region of the
upper jet streak traversing south-central Canada, while also
within the left-exit region of the upper jet streak lifting into
the Front Range and Central Plains. Robust low-mid level moisture
transport turning westward into the maturing Cold Conveyor Belt
(CCB) and maturing TROWAL will reach 2-3 standard deviations above
normal across the Northern Plains per the 00Z GEFS, while
anomalies peak between +3 and +5 across the Upper MS Valley Sunday
night. This as the south-southwesterly LLJ peaks by Sunday night
(~50 kts at 850 mb), while strengthening ENE-NE low-level flow
peaking between 30-40 kts across the backside of the CCB will lead
to a considerable upslope component to the lift across the
foothills and High Plains of south-central and southeast MT into
northeast WY.

The Slight Risk area was largely unchanged. Peak rainfall totals of
2-4+" west and southwest of Billings will combine with high snow
levels and burn scars to locally enhance the flash flooding
potential in this area of Montana. Farther east across the northern
Plains and Upper MS Valley, deep-layer instability will become more
plentiful (MUCAPEs peaking aoa 1,000 J/Kg), while the low-level
moisture transport becomes more robust Sunday night given the
aforementioned uptick in the LLJ. Despite the more favorable deep-
layer thermodynamical profile, the spread in the model QPFs is much
higher over this area, particularly with the heavier rainfall. This
is likely to the more transient (less persistent), mainly WAA-
driven upper level forcing, along with the low-level fronts
remaining upstream of the Upper MS Valley through Sunday night. In
addition, the forward-propagating Corfidi vectors would support a
rather progressive motion of any organized convection that is able
to grow upscale. As a result, the Marginal Risk area was
maintained across the lower (Northern) Plains and Upper MS Valley.

Hurley


Day 2
Valid 12Z Mon Apr 28 2025 - 12Z Tue Apr 29 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS=20
OF THE PLAINS AND INTO THE UPPER MIDWEST...

...20Z Update...

In coordination with UNR/Rapid City, SD; ABR/Aberdeen, SD;
BIS/Bismarck, ND; FGF/Fargo, ND; MPX/Twin Cities, MN; ARX/LaCrosse,
WI; and DLH/Duluth, MN forecast offices, the inherited Slight Risk
was removed with this forecast update.

A mid-level circulation will open into a shortwave trough across=20
the northern Plains and Upper Midwest on Monday-Monday night. Ample
pre-frontal low-mid layer moisture transport and PW values=20
climbing to 1.5-1.75" will make for a favorable thermodynamic=20
profile, along with deep-layer instability as MUCAPEs peak between=20 2,000-3,000 J/Kg. There remains some concern during this period=20
with cell training, especially late Monday-Monday night across the
Upper Midwest and Central Plains with the strengthening LLJ (50-55
kt at 850 mb) and weakening downwind Corfidi Vectors. The 12Z
guidance remains highly variable with where any convection along
the cold front will set up, regardless of training potential, with
some of the guidance into northern Wisconsin and the UP of
Michigan, with more limited potential further west from southeast
ND into northern MN. This more limited potential is due to a
preponderance of the guidance suggesting the dry slot will move
over that area, greatly reducing the time of any rainfall through
the period.

For much of North Dakota southwest into southeastern Montana and
far northern Wyoming, there is a bit higher potential for flash
flooding stemming from rainfall and snowmelt from the northeast
flow against the Bighorns, but for most of that area, soils remain
very dry with an ongoing drought, and it's unlikely with limited
instability on the cold side of the low that rates will overcome
the otherwise sandy soils of the area to result in anything other
than isolated instances of flash flooding.

Hurley/Wegman


Day 3
Valid 12Z Tue Apr 29 2025 - 12Z Wed Apr 30 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF=20 SOUTHWESTERN OKLAHOMA AND NORTH TEXAS...

...20Z Update...

In coordination with OUN/Norman, OK forecast office, a Moderate
Risk upgrade was introduced with this update.

Another potential significant rainfall event will be taking shape
across western portions of the TX-OK Red River Valley northeast
into the Ozarks and Lower MO River Valley. This as the upper trough
west/ridge east amplify and in-turn exhibit slower W-E
progression. This will allow for a more prolonged period of
favorable upper level forcing (coupled southern and northern stream
jet streaks) along a surface front that will become quasi-
stationary across OK- southeast KS into central MO. Robust
synoptic-scale forcing, favorable thermodynamic profiles (Mixed
Layer CAPEs 1000-2000 J/Kg and TPWs 1.5-1.75") and the the enhanced
risk of repetitive convection along the slow moving/stalled
frontal boundary will likely lead to impressive 24 hr rainfall
totals within the Slight Risk area (3-5+ inches, with higher
localized totals per the higher-resolution GEM-Region and RRFS
runs). Tuesday night in particular may bring a more enhanced flash
flood threat, as the LLJ veers and becomes nearly parallel (and of
similar magnitude of) the mean 850-300 mb flow, thereby leading to
weaker forward-propagating Corfidi Vectors and allowing for a
greater risk of cell training.

Much of the Moderate Risk area picked up several inches of heavy
rainfall from a slow-moving and persistent MCS that tracked across
southwestern Oklahoma and north Texas yesterday. This has greatly
diminished FFGs and swelled local rivers, streams, and creeks.
While both today and most of tomorrow will be dry, (with severe
thunderstorm potential tomorrow), it appears unlikely that there
will be enough recovery to return soil conditions to normal by the
time Tuesday's heavy rainfall event gets going. There are therefore
heightened concerns for flash flooding. The Moderate Risk
highlights the hardest hit areas expected to pick up heavy rain
from both yesterday and expected again on Tuesday. Additional
expansions may be needed if forecast rainfall increases further
south and west in areas that were also hard-hit Wednesday, as well
as towards the Northeast from Tuesday's rainfall alone, as the
highest rainfall amounts for the day may be closer to the Oklahoma/Kansas/Missouri/Arkansas corners region. As is common for
forecast areas of thunderstorms, shifts in the axis of heaviest
rainfall are common and therefore adjustments to the outlook areas
may be needed in the coming days.

Hurley/Wegman

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt= __;!!DZ3fjg!_BFtAyj5apHFtVRxuTPsDaRjRin3HDFsxx5xBqCQ4a1Cn2Po7fS18ua1LW6aWi6= JtXXVKq6q8jWiUog9vIzbwkuB4Hs$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt= __;!!DZ3fjg!_BFtAyj5apHFtVRxuTPsDaRjRin3HDFsxx5xBqCQ4a1Cn2Po7fS18ua1LW6aWi6= JtXXVKq6q8jWiUog9vIzb4w7g5TA$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt= __;!!DZ3fjg!_BFtAyj5apHFtVRxuTPsDaRjRin3HDFsxx5xBqCQ4a1Cn2Po7fS18ua1LW6aWi6= JtXXVKq6q8jWiUog9vIzbem6mzSw$=20

=3D =3D =3D
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FOUS30 KWBC 280038
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
838 PM EDT Sun Apr 27 2025

Day 1
Valid 01Z Mon Apr 28 2025 - 12Z Mon Apr 28 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTH-CENTRAL AND SOUTHEASTERN MONTANA...

...01Z Update...
Few changes needed to the previously issued Excessive Rainfall
Discussion. Convection began increasing in coverage during the
afternoon across portions of south central/northeast Wyoming in
proximity to a quasi-stationary north-south oriented deformation
zone. Concern for excessive rainfall is driven by modest amounts of
rainfall falling on a warming snowpack at mid-levels across
portions of south-central/southeast Montana into northeast Wyoming.
Farther to the east in portions of southeast Wyoming into western
South Dakota...flash flooding from convection firing along a well-
defined dry line with easterly flow north of a warm front providing
amply shear. The main concern from this convection looks to be hail
but there is ample moisture flux to support increasing rainfall=20
production and risk of flash flooding from slow moving cells given=20
Flash Flood Guidance values ranging from 1 to 1.5 inches per hours=20
or near 2 inches in 3 hours across far southeast Montana into the=20
Black Hills of South Dakota. The activity farther west is expected=20
to take on a broader coverage of stratiform character later,=20

The Marginal Risk area extending across the remainder of the
Dakotas into Minnesota remained in place without modification. The
expectation remains for thunderstorms to develop later tonight with
an increasing chance for heavy rainfall as the low level jet taps
deeper moisture and transports the moisture/instability into the
region.

Bann

...16Z Update...

Very few changes were needed to the outlook areas with this update.
Guidance remains largely on track, with the Slight Risk across
south-central and southeastern Montana remaining in place.
Moderate rainfall rates up to an inch per hour (heavy in upslope
areas) will combine with snowmelt and burn scars to locally
increase the coverage of instances of flash flooding to widely
scattered. Most of the event will occur tonight, continuing in some
areas into Monday morning.

Southeastern portions of the Marginal were trimmed over Minnesota,
Iowa, and South Dakota with the latest guidance shifting the
potential for training thunderstorms north and west.


Wegman

...Previous Discussion...

...Summary...
Minimal modifications were made to the Slight and Marginal Risk
areas from yesterday's Day 2 ERO.

...Northern High Plains to the Mid Mississippi Valley...
Mid-Upper low migrating across the central Great Basin-central
Rockies during the period will set the stage for robust deep-layer
forcing over the outlook areas as the upper ridge axis moves east.
Helping matters will be coupled upper level jet streaks, i.e. with
the ribbon of enhanced lift within the right-entrance region of the
upper jet streak traversing south-central Canada, while also
within the left-exit region of the upper jet streak lifting into
the Front Range and Central Plains. Robust low-mid level moisture
transport turning westward into the maturing Cold Conveyor Belt
(CCB) and maturing TROWAL will reach 2-3 standard deviations above
normal across the Northern Plains per the 00Z GEFS, while
anomalies peak between +3 and +5 across the Upper MS Valley Sunday
night. This as the south-southwesterly LLJ peaks by Sunday night
(~50 kts at 850 mb), while strengthening ENE-NE low-level flow
peaking between 30-40 kts across the backside of the CCB will lead
to a considerable upslope component to the lift across the
foothills and High Plains of south-central and southeast MT into
northeast WY.

The Slight Risk area was largely unchanged. Peak rainfall totals of
2-4+" west and southwest of Billings will combine with high snow
levels and burn scars to locally enhance the flash flooding
potential in this area of Montana. Farther east across the northern
Plains and Upper MS Valley, deep-layer instability will become more
plentiful (MUCAPEs peaking aoa 1,000 J/Kg), while the low-level
moisture transport becomes more robust Sunday night given the
aforementioned uptick in the LLJ. Despite the more favorable deep-
layer thermodynamical profile, the spread in the model QPFs is much
higher over this area, particularly with the heavier rainfall. This
is likely to the more transient (less persistent), mainly WAA-
driven upper level forcing, along with the low-level fronts
remaining upstream of the Upper MS Valley through Sunday night. In
addition, the forward-propagating Corfidi vectors would support a
rather progressive motion of any organized convection that is able
to grow upscale. As a result, the Marginal Risk area was
maintained across the lower (Northern) Plains and Upper MS Valley.

Hurley


Day 2
Valid 12Z Mon Apr 28 2025 - 12Z Tue Apr 29 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE PLAINS AND INTO THE UPPER MIDWEST...

...20Z Update...

In coordination with UNR/Rapid City, SD; ABR/Aberdeen, SD;
BIS/Bismarck, ND; FGF/Fargo, ND; MPX/Twin Cities, MN; ARX/LaCrosse,
WI; and DLH/Duluth, MN forecast offices, the inherited Slight Risk
was removed with this forecast update.

A mid-level circulation will open into a shortwave trough across
the northern Plains and Upper Midwest on Monday-Monday night. Ample
pre-frontal low-mid layer moisture transport and PW values
climbing to 1.5-1.75" will make for a favorable thermodynamic
profile, along with deep-layer instability as MUCAPEs peak between
2,000-3,000 J/Kg. There remains some concern during this period
with cell training, especially late Monday-Monday night across the
Upper Midwest and Central Plains with the strengthening LLJ (50-55
kt at 850 mb) and weakening downwind Corfidi Vectors. The 12Z
guidance remains highly variable with where any convection along
the cold front will set up, regardless of training potential, with
some of the guidance into northern Wisconsin and the UP of
Michigan, with more limited potential further west from southeast
ND into northern MN. This more limited potential is due to a
preponderance of the guidance suggesting the dry slot will move
over that area, greatly reducing the time of any rainfall through
the period.

For much of North Dakota southwest into southeastern Montana and
far northern Wyoming, there is a bit higher potential for flash
flooding stemming from rainfall and snowmelt from the northeast
flow against the Bighorns, but for most of that area, soils remain
very dry with an ongoing drought, and it's unlikely with limited
instability on the cold side of the low that rates will overcome
the otherwise sandy soils of the area to result in anything other
than isolated instances of flash flooding.

Hurley/Wegman


Day 3
Valid 12Z Tue Apr 29 2025 - 12Z Wed Apr 30 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHWESTERN OKLAHOMA AND NORTH TEXAS...

...20Z Update...

In coordination with OUN/Norman, OK forecast office, a Moderate
Risk upgrade was introduced with this update.

Another potential significant rainfall event will be taking shape
across western portions of the TX-OK Red River Valley northeast
into the Ozarks and Lower MO River Valley. This as the upper trough
west/ridge east amplify and in-turn exhibit slower W-E
progression. This will allow for a more prolonged period of
favorable upper level forcing (coupled southern and northern stream
jet streaks) along a surface front that will become quasi-
stationary across OK- southeast KS into central MO. Robust
synoptic-scale forcing, favorable thermodynamic profiles (Mixed
Layer CAPEs 1000-2000 J/Kg and TPWs 1.5-1.75") and the the enhanced
risk of repetitive convection along the slow moving/stalled
frontal boundary will likely lead to impressive 24 hr rainfall
totals within the Slight Risk area (3-5+ inches, with higher
localized totals per the higher-resolution GEM-Region and RRFS
runs). Tuesday night in particular may bring a more enhanced flash
flood threat, as the LLJ veers and becomes nearly parallel (and of
similar magnitude of) the mean 850-300 mb flow, thereby leading to
weaker forward-propagating Corfidi Vectors and allowing for a
greater risk of cell training.

Much of the Moderate Risk area picked up several inches of heavy
rainfall from a slow-moving and persistent MCS that tracked across
southwestern Oklahoma and north Texas yesterday. This has greatly
diminished FFGs and swelled local rivers, streams, and creeks.
While both today and most of tomorrow will be dry, (with severe
thunderstorm potential tomorrow), it appears unlikely that there
will be enough recovery to return soil conditions to normal by the
time Tuesday's heavy rainfall event gets going. There are therefore
heightened concerns for flash flooding. The Moderate Risk
highlights the hardest hit areas expected to pick up heavy rain
from both yesterday and expected again on Tuesday. Additional
expansions may be needed if forecast rainfall increases further
south and west in areas that were also hard-hit Wednesday, as well
as towards the Northeast from Tuesday's rainfall alone, as the
highest rainfall amounts for the day may be closer to the Oklahoma/Kansas/Missouri/Arkansas corners region. As is common for
forecast areas of thunderstorms, shifts in the axis of heaviest
rainfall are common and therefore adjustments to the outlook areas
may be needed in the coming days.

Hurley/Wegman

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt= __;!!DZ3fjg!7YddaiAQS0SbyLMtFiksr5THjFrosztOZT4qLu9WxUsp4NUYZzS78eG3B1xMQxJ= EpbymMGzVMnFpeESdJp6RDTbQO6k$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt= __;!!DZ3fjg!7YddaiAQS0SbyLMtFiksr5THjFrosztOZT4qLu9WxUsp4NUYZzS78eG3B1xMQxJ= EpbymMGzVMnFpeESdJp6RQNrsyRE$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt= __;!!DZ3fjg!7YddaiAQS0SbyLMtFiksr5THjFrosztOZT4qLu9WxUsp4NUYZzS78eG3B1xMQxJ= EpbymMGzVMnFpeESdJp6R4BdLozE$=20

=3D =3D =3D
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FOUS30 KWBC 280739
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
339 AM EDT Mon Apr 28 2025

Day 1
Valid 12Z Mon Apr 28 2025 - 12Z Tue Apr 29 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE PLAINS AND INTO THE UPPER MIDWEST...

...Northern Plains & Upper Midwest...

The period in question will remain active on the rainfall front, but=20
a few key pieces will be missing, relegating flash flood prospects=20
closer to the MRGL risk category as inherited from the previous=20
update. Upper level progression from the Inter-Mountain West through=20
the Northern Plains and Upper Midwest will exhibit a decaying mid to=20
upper level structure of a closed ULL out west with a more sheared,=20 progressive pieces ejecting into the High Plains and propagating=20 northeastward through MN and northern WI. The evolution is such that=20
a reasonable upper forcing pattern will materialize with scattered=20
to widespread convective initiation located downstream of a broad=20
diffluent axis situated from the Front Range through the Upper=20
Midwest. Instability on the order of 1500-2500 J/kg of MUCAPE will=20
be present ahead of the mean trough with ample mid-level=20
perturbations ejecting into the northern tier of the CONUS during=20
the morning and afternoon periods. To round off the setup, a budding=20 140-150kt jet streak will be oriented over south-central Canada=20
providing a solid RER dynamic suitable for maintaining a more=20
organized precipitation element over the northern tier of the CONUS.=20
Despite the above support for convective prospects, the pattern will=20
be in the process of breaking down as the upper low out west becomes=20
a more open wave with the primary bulk of mid-level energy quickly=20
ejecting northeast with a textbook strong PVA to NVA signature as=20
the energy vacates over the northern Lakes. This setup has shifted=20
to a very front loaded convective scheme over the Northern Plains=20
into the Upper Midwest with a majority of the convective pattern=20
quickly ushering east-northeastward through the course of the=20
morning and afternoon periods. By the evening, remnant convective=20
elements will become more scattered in nature, eventually moving out=20
of the primary area of interest after nightfall leading to a=20
diminished threat for the end of the forecast cycle.

00z HREF EAS probs remain pretty elevated (50-80%) for at least 1"=20
across the eastern half of ND through Northern MN, but a sharp=20
decline in probs for >2" leading the case for more isolated to=20
widely scattered flash flood prospects in the given pattern. There=20
are some respectable probabilities in the neighborhood scheme for=20

2" within the Arrowhead of MN back over the the Dakotas (50-80%),=20

but again a sharp decline once into the >3" fields limiting the=20
upper bounds of the potential. A few areas may see between 3-5" at=20
the peak, but those will likely be few and far between for an area=20
that is actually in a low-end drought overall. Considering the soil=20
type and antecedent dry conditions in the region, the inherited MRGL=20
was maintained with little change in the risk area over the Northern=20
Plains into the Upper Midwest.=20


...Central and Southern Plains

The Central and Southern Plains will reside within a broad warm-
sector environment positioned between a vacated warm front pressing=20
north through the Mississippi Valley and a slow-moving cold front=20
through the High Plains with a secondary cold forecast to plunge=20
southeast through the Northern and Central High Plains by the end of=20
the forecast cycle. A fairly meridional upper pattern will end up=20
being a key factor in the eventual ejection of stronger shortwaves=20
out of Chihuahua, MX, barreling northeastward through the Southern=20
Plains with scattered to widespread thunderstorm development along=20
and east of a dry line situated over West TX. The combination of=20
relevant buoyancy/instability positioned over the Southern and=20
Central U.S. coupled with favored regional ascent and=20
thermodynamics will create a period of late-afternoon and evening=20
convective development capable of localized flash flood prospects.=20
Recent heavy rain episodes have contributed to an elevated soil=20
moisture presence from the Red River Basin up through much of OK=20
into southeast KS, and MO. Rainfall totals up to 2-3" in a short=20
time frame will be capable of causing flash flooding within the=20
bounds of those areas that exhibit those moist top-layer soils=20
since the time frame for recovery will have been short. 00z HREF=20 neighborhood probs for >1" are respectable (50-70%) within portions
of the Central and Southern Plains with the focus generally over=20 north-central OK, Concho Valley, and Western Rolling Plains of West
TX. Probabilities for >2" are very low leaving the threat for=20
flash flooding fairly conditional and likely more reserved for more
sensitive areas within urbanized zones and areas more susceptible=20
due to low-water crossings.=20

Kleebauer


Day 2
Valid 12Z Tue Apr 29 2025 - 12Z Wed Apr 30 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN PLAINS INTO THE MISSOURI VALLEY...

The combination of favorable buoyancy and upper level dynamics=20
within the confines of a quasi-stationary front across the Southern=20
Plains to Mid-Mississippi Valley will create an environment=20
conducive for locally heavy rainfall over an area still recovering=20
from previous heavy rain episodes. Models are in agreement on the=20
placement of a west-southwest to east-northeast oriented stationary=20
front extending from the Western Rolling Plains of TX up through the=20
Red River Basin, bisecting much of central and northeastern OK, up=20
through the Ozarks of MO. Multiple mid-level shortwaves will eject=20
northeast out of MX creating a multi-wave convective initiation=20
cycle that will eventually move over the same areas repeatedly=20
during the course of the D2 time frame. Instability markers are very=20 favorable within the axis denoted above with sufficient buoyancy=20
on the order of 1500-3000 J/kg of MLCAPE situated across West TX to
points northeast through the Red River into OK. Assessment of NASA
SPoRT soil moisture anomalies pinpoint a fairly large area of=20
well- saturated top-layer soils running upwards of 90-98th=20
percentile across southwestern OK up into the Norman/OKC metro=20
corridor thanks to a significant flash flood episode that occurred=20
less than 36 hrs prior. Further northeast, soils are still=20
recovering from multiple rounds of convection the past several days
with elevated top-layer soils also running high within the 75-90th
percentile across the Tulsa CWA up through southwestern MO.=20
Considering guidance privy to these areas also being the=20
beneficiary of multiple convective rounds over the course of=20
Tuesday into Wednesday, there is a growing necessity for a higher=20
risk level forecast in these zones. Ensemble bias corrected=20
guidance has steadily increased the areal QPF averages from run to=20
run within these confines of northeast OK up through western MO, a=20
testament to the growing consensus in the heavy QPF footprint.=20

00z CAMs are only within the initial 12 hrs. of the period in=20
question, but the signs even prior to the bulk of the heavier=20
convective signature (Heaviest after 00z/29) are very much favorable=20
for potentially significant flash flood prospects. 00z HREF 6-hr FFG=20 exceedance probabilities for the 18-00z time frame are already=20
between 15-30% on the initial stages of heavier precip across the=20
Red River Basin of North TX into Southwestern OK up through Central=20
and Northeast OK. This is very likely due to the convective episode=20
stemming from the first mid-level shortwave ejecting northeast=20
generating a period of convection during the afternoon hrs. on=20
Tuesday. By Tuesday evening, large scale ascent will increase=20
substantially over the Southern Plains a potent mid-level shortwave=20
pivots over NM with a robust diffluent signature present downstream=20
into West TX and the adjacent Red River Basin. At the surface, a=20
cold front will motion south through the High Plains with an=20
expected convergence pattern developing as it moves into the already=20
present quasi-stationary front in place across the region. The=20
combination of the evolving surface and upper pattern will yield a=20
robust convective footprint across the Southern High Plains of TX up=20
through the Red River Basin, pressing northeast given the steering=20
pattern aloft. The episodic nature of the heavy precip will garner=20
limited recovery for areas already impacted by one round of=20
thunderstorms earlier in the period leaving a better opportunity for=20
flash flooding potential for the nocturnal period. There's some=20
discrepancy on exact placement of the more prolific convective=20
cores, but the one constant is the area expected to see the threat=20
is generally pinned down at this lead.=20

After coordination with local WFOs over North TX through OK,=20
Southeast KS, and Southwest MO...the previous MDT risk was expanded=20
to include much of Central and Northeast OK up through Southeast KS=20
into Southwest MO. A large SLGT encompasses areas surrounding the=20
MDT risk with areas like the eastern Permian Basin, Concho Valley,=20
and the Southern half of MO (Excluding the MDT risk area) within the=20
SLGT corridor. A broad MRGL extends from the rest of the Permian=20
Basin all the way through the Central and Northern Ohio Valley into=20 Northwest PA and far Southwest NY state as scattered convective=20
clusters will have the opportunity in these zones to produce locally=20
heavy rainfall capable of isolated flash flood prospects.

Kleebauer


Day 3
Valid 12Z Wed Apr 30 2025 - 12Z Thu May 01 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE ARKLATEX, EASTERN OKLAHOMA, AND WESTERN OZARKS...

The evolving upper air pattern along with the slow progression of a=20
cold front will yield another period of significant rainfall within=20
the confines of the Southern Plains to points east into the ArkLaTex=20
and Lower Mississippi Valley. Strong mid-level vorticity maxima will=20 translate eastward around the base of a potent mean trough=20
traversing the center of the CONUS. At the surface, a cold front=20
will be propagating eastward into the above corridors with ample=20
convection situated along and ahead of the front as it maneuvers its=20
way east. By the afternoon period Wednesday, sufficient diurnal heat=20
flux from typical daytime heating will provide ample instability=20
along and east of I-35 with a very buoyant forecast sounding being=20
depicted from multiple deterministic outputs, including the global=20
scale models, a testament to a pretty agitated environment. Above=20
normal PWATs on the order of +1 to 2 deviations coupled with a=20
textbook boundary layer convergence pattern will yield a swath of=20
heavy thunderstorms extending from Central TX to points northeast=20
into the vicinity of the ArkLaTex up through northwestern AR.=20
Latest deterministic output is between 2-4" on an areal average=20
basis with local maxima between 5-8" pending model depiction.=20
Ensemble means are generally between 2-3" for the period with the=20
bias corrected mean closer to 3-4" across the ArkLaTex up through=20
the western Ozarks, a signal that usually precludes a "ramp up" of=20
the precip depiction once we get closer to the range of the CAMs=20
guidance. Area soil moisture anomalies are once again fairly wet=20
across portions of eastern OK up into northern AR, leading to a=20
lower FFG parameter to meet for flash flood potential. Rainfall=20
rates will be between 1.5- 3"/hr during cell peaks, enough of a=20
signal to induce flash flood prospects even into northeastern TX=20
where soils are drier compared to areas further north. The D2-3=20
total QPF is now between 3-6" over the above areas, a defined=20
corridor for waves of heavy rainfall anticipated.=20

In coordination with local WFOs across OK, AR, TX, and MO...a MDT=20
risk was introduced to cover for the expected heavy rain threat over=20
areas anticipated to see significant convective impacts for=20
Wednesday into Thursday morning. Future updates will be provided as=20
we move closer to the event as later CAMs integration for the=20
forecast will provide better detail on forecast QPF maxima=20
placement, as well as magnitude.=20=20

Kleebauer


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt= __;!!DZ3fjg!6ykpAxWmwiEw-A-hCaI63OzbNCQK1eED7_o7AoFYC0pCbJStzKQBKTSlMbAR7Un= 7GpCUt4kU2LoCKFDdTlAXUn3ehag$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt= __;!!DZ3fjg!6ykpAxWmwiEw-A-hCaI63OzbNCQK1eED7_o7AoFYC0pCbJStzKQBKTSlMbAR7Un= 7GpCUt4kU2LoCKFDdTlAXXUSLH_4$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt= __;!!DZ3fjg!6ykpAxWmwiEw-A-hCaI63OzbNCQK1eED7_o7AoFYC0pCbJStzKQBKTSlMbAR7Un= 7GpCUt4kU2LoCKFDdTlAXHGjToTQ$=20

=3D =3D =3D
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FOUS30 KWBC 280742
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
342 AM EDT Mon Apr 28 2025

Day 1
Valid 12Z Mon Apr 28 2025 - 12Z Tue Apr 29 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE PLAINS AND INTO THE UPPER MIDWEST...

...Northern Plains & Upper Midwest...

The period in question will remain active on the rainfall front, but
a few key pieces will be missing, relegating flash flood prospects
closer to the MRGL risk category as inherited from the previous
update. Upper level progression from the Inter-Mountain West through
the Northern Plains and Upper Midwest will exhibit a decaying mid to
upper level structure of a closed ULL out west with a more sheared,
progressive pieces ejecting into the High Plains and propagating
northeastward through MN and northern WI. The evolution is such that
a reasonable upper forcing pattern will materialize with scattered
to widespread convective initiation located downstream of a broad
diffluent axis situated from the Front Range through the Upper
Midwest. Instability on the order of 1500-2500 J/kg of MUCAPE will
be present ahead of the mean trough with ample mid-level
perturbations ejecting into the northern tier of the CONUS during
the morning and afternoon periods. To round off the setup, a budding
140-150kt jet streak will be oriented over south-central Canada
providing a solid RER dynamic suitable for maintaining a more
organized precipitation element over the northern tier of the CONUS.
Despite the above support for convective prospects, the pattern will
be in the process of breaking down as the upper low out west becomes
a more open wave with the primary bulk of mid-level energy quickly
ejecting northeast with a textbook strong PVA to NVA signature as
the energy vacates over the northern Lakes. This setup has shifted
to a very front loaded convective scheme over the Northern Plains
into the Upper Midwest with a majority of the convective pattern
quickly ushering east-northeastward through the course of the
morning and afternoon periods. By the evening, remnant convective
elements will become more scattered in nature, eventually moving out
of the primary area of interest after nightfall leading to a
diminished threat for the end of the forecast cycle.

00z HREF EAS probs remain pretty elevated (50-80%) for at least 1"
across the eastern half of ND through Northern MN, but a sharp
decline in probs for >2" leading the case for more isolated to
widely scattered flash flood prospects in the given pattern. There
are some respectable probabilities in the neighborhood scheme for

2" within the Arrowhead of MN back over the the Dakotas (50-80%),

but again a sharp decline once into the >3" fields limiting the
upper bounds of the potential. A few areas may see between 3-5" at
the peak, but those will likely be few and far between for an area
that is actually in a low-end drought overall. Considering the soil
type and antecedent dry conditions in the region, the inherited MRGL
was maintained with little change in the risk area over the Northern
Plains into the Upper Midwest.


...Central and Southern Plains...

The Central and Southern Plains will reside within a broad warm-
sector environment positioned between a vacated warm front pressing
north through the Mississippi Valley and a slow-moving cold front
through the High Plains with a secondary cold forecast to plunge
southeast through the Northern and Central High Plains by the end of
the forecast cycle. A fairly meridional upper pattern will end up
being a key factor in the eventual ejection of stronger shortwaves
out of Chihuahua, MX, barreling northeastward through the Southern
Plains with scattered to widespread thunderstorm development along
and east of a dry line situated over West TX. The combination of
relevant buoyancy/instability positioned over the Southern and
Central U.S. coupled with favored regional ascent and
thermodynamics will create a period of late-afternoon and evening
convective development capable of localized flash flood prospects.
Recent heavy rain episodes have contributed to an elevated soil
moisture presence from the Red River Basin up through much of OK
into southeast KS, and MO. Rainfall totals up to 2-3" in a short
time frame will be capable of causing flash flooding within the
bounds of those areas that exhibit those moist top-layer soils
since the time frame for recovery will have been short. 00z HREF
neighborhood probs for >1" are respectable (50-70%) within portions
of the Central and Southern Plains with the focus generally over
north-central OK, Concho Valley, and Western Rolling Plains of West
TX. Probabilities for >2" are very low leaving the threat for
flash flooding fairly conditional and likely more reserved for more
sensitive areas within urbanized zones and areas more susceptible
due to low-water crossings.

Kleebauer


Day 2
Valid 12Z Tue Apr 29 2025 - 12Z Wed Apr 30 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN PLAINS INTO THE MISSOURI VALLEY...

The combination of favorable buoyancy and upper level dynamics
within the confines of a quasi-stationary front across the Southern
Plains to Mid-Mississippi Valley will create an environment
conducive for locally heavy rainfall over an area still recovering
from previous heavy rain episodes. Models are in agreement on the
placement of a west-southwest to east-northeast oriented stationary
front extending from the Western Rolling Plains of TX up through the
Red River Basin, bisecting much of central and northeastern OK, up
through the Ozarks of MO. Multiple mid-level shortwaves will eject
northeast out of MX creating a multi-wave convective initiation
cycle that will eventually move over the same areas repeatedly
during the course of the D2 time frame. Instability markers are very
favorable within the axis denoted above with sufficient buoyancy
on the order of 1500-3000 J/kg of MLCAPE situated across West TX to
points northeast through the Red River into OK. Assessment of NASA
SPoRT soil moisture anomalies pinpoint a fairly large area of
well- saturated top-layer soils running upwards of 90-98th
percentile across southwestern OK up into the Norman/OKC metro
corridor thanks to a significant flash flood episode that occurred
less than 36 hrs prior. Further northeast, soils are still
recovering from multiple rounds of convection the past several days
with elevated top-layer soils also running high within the 75-90th
percentile across the Tulsa CWA up through southwestern MO.
Considering guidance privy to these areas also being the
beneficiary of multiple convective rounds over the course of
Tuesday into Wednesday, there is a growing necessity for a higher
risk level forecast in these zones. Ensemble bias corrected
guidance has steadily increased the areal QPF averages from run to
run within these confines of northeast OK up through western MO, a
testament to the growing consensus in the heavy QPF footprint.

00z CAMs are only within the initial 12 hrs. of the period in
question, but the signs even prior to the bulk of the heavier
convective signature (Heaviest after 00z/29) are very much favorable
for potentially significant flash flood prospects. 00z HREF 6-hr FFG
exceedance probabilities for the 18-00z time frame are already
between 15-30% on the initial stages of heavier precip across the
Red River Basin of North TX into Southwestern OK up through Central
and Northeast OK. This is very likely due to the convective episode
stemming from the first mid-level shortwave ejecting northeast
generating a period of convection during the afternoon hrs. on
Tuesday. By Tuesday evening, large scale ascent will increase
substantially over the Southern Plains a potent mid-level shortwave
pivots over NM with a robust diffluent signature present downstream
into West TX and the adjacent Red River Basin. At the surface, a
cold front will motion south through the High Plains with an
expected convergence pattern developing as it moves into the already
present quasi-stationary front in place across the region. The
combination of the evolving surface and upper pattern will yield a
robust convective footprint across the Southern High Plains of TX up
through the Red River Basin, pressing northeast given the steering
pattern aloft. The episodic nature of the heavy precip will garner
limited recovery for areas already impacted by one round of
thunderstorms earlier in the period leaving a better opportunity for
flash flooding potential for the nocturnal period. There's some
discrepancy on exact placement of the more prolific convective
cores, but the one constant is the area expected to see the threat
is generally pinned down at this lead.

After coordination with local WFOs over North TX through OK,
Southeast KS, and Southwest MO...the previous MDT risk was expanded
to include much of Central and Northeast OK up through Southeast KS
into Southwest MO. A large SLGT encompasses areas surrounding the
MDT risk with areas like the eastern Permian Basin, Concho Valley,
and the Southern half of MO (Excluding the MDT risk area) within the
SLGT corridor. A broad MRGL extends from the rest of the Permian
Basin all the way through the Central and Northern Ohio Valley into
Northwest PA and far Southwest NY state as scattered convective
clusters will have the opportunity in these zones to produce locally
heavy rainfall capable of isolated flash flood prospects.

Kleebauer


Day 3
Valid 12Z Wed Apr 30 2025 - 12Z Thu May 01 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE ARKLATEX, EASTERN OKLAHOMA, AND WESTERN OZARKS...

The evolving upper air pattern along with the slow progression of a
cold front will yield another period of significant rainfall within
the confines of the Southern Plains to points east into the ArkLaTex
and Lower Mississippi Valley. Strong mid-level vorticity maxima will
translate eastward around the base of a potent mean trough
traversing the center of the CONUS. At the surface, a cold front
will be propagating eastward into the above corridors with ample
convection situated along and ahead of the front as it maneuvers its
way east. By the afternoon period Wednesday, sufficient diurnal heat
flux from typical daytime heating will provide ample instability
along and east of I-35 with a very buoyant forecast sounding being
depicted from multiple deterministic outputs, including the global
scale models, a testament to a pretty agitated environment. Above
normal PWATs on the order of +1 to 2 deviations coupled with a
textbook boundary layer convergence pattern will yield a swath of
heavy thunderstorms extending from Central TX to points northeast
into the vicinity of the ArkLaTex up through northwestern AR.
Latest deterministic output is between 2-4" on an areal average
basis with local maxima between 5-8" pending model depiction.
Ensemble means are generally between 2-3" for the period with the
bias corrected mean closer to 3-4" across the ArkLaTex up through
the western Ozarks, a signal that usually precludes a "ramp up" of
the precip depiction once we get closer to the range of the CAMs
guidance. Area soil moisture anomalies are once again fairly wet
across portions of eastern OK up into northern AR, leading to a
lower FFG parameter to meet for flash flood potential. Rainfall
rates will be between 1.5- 3"/hr during cell peaks, enough of a
signal to induce flash flood prospects even into northeastern TX
where soils are drier compared to areas further north. The D2-3
total QPF is now between 3-6" over the above areas, a defined
corridor for waves of heavy rainfall anticipated.

In coordination with local WFOs across OK, AR, TX, and MO...a MDT
risk was introduced to cover for the expected heavy rain threat over
areas anticipated to see significant convective impacts for
Wednesday into Thursday morning. Future updates will be provided as
we move closer to the event as later CAMs integration for the
forecast will provide better detail on forecast QPF maxima
placement, as well as magnitude.

Kleebauer


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt= __;!!DZ3fjg!4FeAE_mehf5E48r340xKTvoQHWz2rCkJZdDWIl5drjTDmMRngbw3ALgynkt85qn= geZ3juixp8Ugpih4iBzVyNEyD8GE$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt= __;!!DZ3fjg!4FeAE_mehf5E48r340xKTvoQHWz2rCkJZdDWIl5drjTDmMRngbw3ALgynkt85qn= geZ3juixp8Ugpih4iBzVyWxgOzMc$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt= __;!!DZ3fjg!4FeAE_mehf5E48r340xKTvoQHWz2rCkJZdDWIl5drjTDmMRngbw3ALgynkt85qn= geZ3juixp8Ugpih4iBzVyYn_Szas$=20

=3D =3D =3D
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FOUS30 KWBC 281549
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1149 AM EDT Mon Apr 28 2025

Day 1
Valid 16Z Mon Apr 28 2025 - 12Z Tue Apr 29 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE RED RIVER VALLEY AND CENTRAL/SOUTHERN OKLAHOMA...

16z update...for Southern Plains...

A few 12z CAMs suggest a strong cluster/few super-cells that will=20
be capable of intense heavy rainfall this afternoon across portions
of KS/OK into Northwest Texas. Recent heavy rainfall in the=20
region, highlighted by NASA SPoRT 0-40cm saturation ratios over=20
70-80% and well above normal in the 90-95% percentiles suggest=20
little infiltration is expected even in rural locations. There=20
remains sufficient uncertainty to the precise latitude of these=20
individual cells or small clusters to have high confidence. 12z=20
HREF probability have increased across the most saturated areas=20
with greatest 1" and 2" per hour and 3-hour periods and now as high
as 30% across the most saturated areas of Southern Oklahoma. In=20
coordination with local forecast offices, this is sufficient=20
highlight a small upgrade to a Slight Risk mainly along the the Red
River into central OK where both meteorology and hydrology overlap
the most.=20

Gallina

~~~~Prior Discussions~~~~

...Northern Plains & Upper Midwest...

The period in question will remain active on the rainfall front, but
a few key pieces will be missing, relegating flash flood prospects
closer to the MRGL risk category as inherited from the previous
update. Upper level progression from the Inter-Mountain West through
the Northern Plains and Upper Midwest will exhibit a decaying mid to
upper level structure of a closed ULL out west with a more sheared,
progressive pieces ejecting into the High Plains and propagating
northeastward through MN and northern WI. The evolution is such that
a reasonable upper forcing pattern will materialize with scattered
to widespread convective initiation located downstream of a broad
diffluent axis situated from the Front Range through the Upper
Midwest. Instability on the order of 1500-2500 J/kg of MUCAPE will
be present ahead of the mean trough with ample mid-level
perturbations ejecting into the northern tier of the CONUS during
the morning and afternoon periods. To round off the setup, a budding
140-150kt jet streak will be oriented over south-central Canada
providing a solid RER dynamic suitable for maintaining a more
organized precipitation element over the northern tier of the CONUS.
Despite the above support for convective prospects, the pattern will
be in the process of breaking down as the upper low out west becomes
a more open wave with the primary bulk of mid-level energy quickly
ejecting northeast with a textbook strong PVA to NVA signature as
the energy vacates over the northern Lakes. This setup has shifted
to a very front loaded convective scheme over the Northern Plains
into the Upper Midwest with a majority of the convective pattern
quickly ushering east-northeastward through the course of the
morning and afternoon periods. By the evening, remnant convective
elements will become more scattered in nature, eventually moving out
of the primary area of interest after nightfall leading to a
diminished threat for the end of the forecast cycle.

00z HREF EAS probs remain pretty elevated (50-80%) for at least 1"
across the eastern half of ND through Northern MN, but a sharp
decline in probs for >2" leading the case for more isolated to
widely scattered flash flood prospects in the given pattern. There
are some respectable probabilities in the neighborhood scheme for

2" within the Arrowhead of MN back over the the Dakotas (50-80%),

but again a sharp decline once into the >3" fields limiting the
upper bounds of the potential. A few areas may see between 3-5" at
the peak, but those will likely be few and far between for an area
that is actually in a low-end drought overall. Considering the soil
type and antecedent dry conditions in the region, the inherited MRGL
was maintained with little change in the risk area over the Northern
Plains into the Upper Midwest.


...Central and Southern Plains...

The Central and Southern Plains will reside within a broad warm-
sector environment positioned between a vacated warm front pressing
north through the Mississippi Valley and a slow-moving cold front
through the High Plains with a secondary cold forecast to plunge
southeast through the Northern and Central High Plains by the end of
the forecast cycle. A fairly meridional upper pattern will end up
being a key factor in the eventual ejection of stronger shortwaves
out of Chihuahua, MX, barreling northeastward through the Southern
Plains with scattered to widespread thunderstorm development along
and east of a dry line situated over West TX. The combination of
relevant buoyancy/instability positioned over the Southern and
Central U.S. coupled with favored regional ascent and
thermodynamics will create a period of late-afternoon and evening
convective development capable of localized flash flood prospects.
Recent heavy rain episodes have contributed to an elevated soil
moisture presence from the Red River Basin up through much of OK
into southeast KS, and MO. Rainfall totals up to 2-3" in a short
time frame will be capable of causing flash flooding within the
bounds of those areas that exhibit those moist top-layer soils
since the time frame for recovery will have been short. 00z HREF
neighborhood probs for >1" are respectable (50-70%) within portions
of the Central and Southern Plains with the focus generally over
north-central OK, Concho Valley, and Western Rolling Plains of West
TX. Probabilities for >2" are very low leaving the threat for
flash flooding fairly conditional and likely more reserved for more
sensitive areas within urbanized zones and areas more susceptible
due to low-water crossings.

Kleebauer


Day 2
Valid 12Z Tue Apr 29 2025 - 12Z Wed Apr 30 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN PLAINS INTO THE MISSOURI VALLEY...

The combination of favorable buoyancy and upper level dynamics
within the confines of a quasi-stationary front across the Southern
Plains to Mid-Mississippi Valley will create an environment
conducive for locally heavy rainfall over an area still recovering
from previous heavy rain episodes. Models are in agreement on the
placement of a west-southwest to east-northeast oriented stationary
front extending from the Western Rolling Plains of TX up through the
Red River Basin, bisecting much of central and northeastern OK, up
through the Ozarks of MO. Multiple mid-level shortwaves will eject
northeast out of MX creating a multi-wave convective initiation
cycle that will eventually move over the same areas repeatedly
during the course of the D2 time frame. Instability markers are very
favorable within the axis denoted above with sufficient buoyancy
on the order of 1500-3000 J/kg of MLCAPE situated across West TX to
points northeast through the Red River into OK. Assessment of NASA
SPoRT soil moisture anomalies pinpoint a fairly large area of
well- saturated top-layer soils running upwards of 90-98th
percentile across southwestern OK up into the Norman/OKC metro
corridor thanks to a significant flash flood episode that occurred
less than 36 hrs prior. Further northeast, soils are still
recovering from multiple rounds of convection the past several days
with elevated top-layer soils also running high within the 75-90th
percentile across the Tulsa CWA up through southwestern MO.
Considering guidance privy to these areas also being the
beneficiary of multiple convective rounds over the course of
Tuesday into Wednesday, there is a growing necessity for a higher
risk level forecast in these zones. Ensemble bias corrected
guidance has steadily increased the areal QPF averages from run to
run within these confines of northeast OK up through western MO, a
testament to the growing consensus in the heavy QPF footprint.

00z CAMs are only within the initial 12 hrs. of the period in
question, but the signs even prior to the bulk of the heavier
convective signature (Heaviest after 00z/29) are very much favorable
for potentially significant flash flood prospects. 00z HREF 6-hr FFG
exceedance probabilities for the 18-00z time frame are already
between 15-30% on the initial stages of heavier precip across the
Red River Basin of North TX into Southwestern OK up through Central
and Northeast OK. This is very likely due to the convective episode
stemming from the first mid-level shortwave ejecting northeast
generating a period of convection during the afternoon hrs. on
Tuesday. By Tuesday evening, large scale ascent will increase
substantially over the Southern Plains a potent mid-level shortwave
pivots over NM with a robust diffluent signature present downstream
into West TX and the adjacent Red River Basin. At the surface, a
cold front will motion south through the High Plains with an
expected convergence pattern developing as it moves into the already
present quasi-stationary front in place across the region. The
combination of the evolving surface and upper pattern will yield a
robust convective footprint across the Southern High Plains of TX up
through the Red River Basin, pressing northeast given the steering
pattern aloft. The episodic nature of the heavy precip will garner
limited recovery for areas already impacted by one round of
thunderstorms earlier in the period leaving a better opportunity for
flash flooding potential for the nocturnal period. There's some
discrepancy on exact placement of the more prolific convective
cores, but the one constant is the area expected to see the threat
is generally pinned down at this lead.

After coordination with local WFOs over North TX through OK,
Southeast KS, and Southwest MO...the previous MDT risk was expanded
to include much of Central and Northeast OK up through Southeast KS
into Southwest MO. A large SLGT encompasses areas surrounding the
MDT risk with areas like the eastern Permian Basin, Concho Valley,
and the Southern half of MO (Excluding the MDT risk area) within the
SLGT corridor. A broad MRGL extends from the rest of the Permian
Basin all the way through the Central and Northern Ohio Valley into
Northwest PA and far Southwest NY state as scattered convective
clusters will have the opportunity in these zones to produce locally
heavy rainfall capable of isolated flash flood prospects.

Kleebauer


Day 3
Valid 12Z Wed Apr 30 2025 - 12Z Thu May 01 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE ARKLATEX, EASTERN OKLAHOMA, AND WESTERN OZARKS...

The evolving upper air pattern along with the slow progression of a
cold front will yield another period of significant rainfall within
the confines of the Southern Plains to points east into the ArkLaTex
and Lower Mississippi Valley. Strong mid-level vorticity maxima will
translate eastward around the base of a potent mean trough
traversing the center of the CONUS. At the surface, a cold front
will be propagating eastward into the above corridors with ample
convection situated along and ahead of the front as it maneuvers its
way east. By the afternoon period Wednesday, sufficient diurnal heat
flux from typical daytime heating will provide ample instability
along and east of I-35 with a very buoyant forecast sounding being
depicted from multiple deterministic outputs, including the global
scale models, a testament to a pretty agitated environment. Above
normal PWATs on the order of +1 to 2 deviations coupled with a
textbook boundary layer convergence pattern will yield a swath of
heavy thunderstorms extending from Central TX to points northeast
into the vicinity of the ArkLaTex up through northwestern AR.
Latest deterministic output is between 2-4" on an areal average
basis with local maxima between 5-8" pending model depiction.
Ensemble means are generally between 2-3" for the period with the
bias corrected mean closer to 3-4" across the ArkLaTex up through
the western Ozarks, a signal that usually precludes a "ramp up" of
the precip depiction once we get closer to the range of the CAMs
guidance. Area soil moisture anomalies are once again fairly wet
across portions of eastern OK up into northern AR, leading to a
lower FFG parameter to meet for flash flood potential. Rainfall
rates will be between 1.5- 3"/hr during cell peaks, enough of a
signal to induce flash flood prospects even into northeastern TX
where soils are drier compared to areas further north. The D2-3
total QPF is now between 3-6" over the above areas, a defined
corridor for waves of heavy rainfall anticipated.

In coordination with local WFOs across OK, AR, TX, and MO...a MDT
risk was introduced to cover for the expected heavy rain threat over
areas anticipated to see significant convective impacts for
Wednesday into Thursday morning. Future updates will be provided as
we move closer to the event as later CAMs integration for the
forecast will provide better detail on forecast QPF maxima
placement, as well as magnitude.

Kleebauer


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt= __;!!DZ3fjg!45pU7aYaXrh2KU5vM5WUbQISU37oOqEd9v-1TTs66zhEK5_3LPcao74Uk9yyHAp= W8m8mJWCUtuKWFXO3W-tDpGz2zlk$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt= __;!!DZ3fjg!45pU7aYaXrh2KU5vM5WUbQISU37oOqEd9v-1TTs66zhEK5_3LPcao74Uk9yyHAp= W8m8mJWCUtuKWFXO3W-tDCZYOPIs$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt= __;!!DZ3fjg!45pU7aYaXrh2KU5vM5WUbQISU37oOqEd9v-1TTs66zhEK5_3LPcao74Uk9yyHAp= W8m8mJWCUtuKWFXO3W-tD6PtLlr4$=20

=3D =3D =3D
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FOUS30 KWBC 282023
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
423 PM EDT Mon Apr 28 2025

Day 1
Valid 16Z Mon Apr 28 2025 - 12Z Tue Apr 29 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE RED RIVER VALLEY AND CENTRAL/SOUTHERN OKLAHOMA...

16z update...for Southern Plains...

A few 12z CAMs suggest a strong cluster/few super-cells that will
be capable of intense heavy rainfall this afternoon across portions
of KS/OK into Northwest Texas. Recent heavy rainfall in the
region, highlighted by NASA SPoRT 0-40cm saturation ratios over
70-80% and well above normal in the 90-95% percentiles suggest
little infiltration is expected even in rural locations. There
remains sufficient uncertainty to the precise latitude of these
individual cells or small clusters to have high confidence. 12z
HREF probability have increased across the most saturated areas
with greatest 1" and 2" per hour and 3-hour periods and now as high
as 30% across the most saturated areas of Southern Oklahoma. In
coordination with local forecast offices, this is sufficient
highlight a small upgrade to a Slight Risk mainly along the the Red
River into central OK where both meteorology and hydrology overlap
the most.

Gallina

~~~~Prior Discussions~~~~

...Northern Plains & Upper Midwest...

The period in question will remain active on the rainfall front, but
a few key pieces will be missing, relegating flash flood prospects
closer to the MRGL risk category as inherited from the previous
update. Upper level progression from the Inter-Mountain West through
the Northern Plains and Upper Midwest will exhibit a decaying mid to
upper level structure of a closed ULL out west with a more sheared,
progressive pieces ejecting into the High Plains and propagating
northeastward through MN and northern WI. The evolution is such that
a reasonable upper forcing pattern will materialize with scattered
to widespread convective initiation located downstream of a broad
diffluent axis situated from the Front Range through the Upper
Midwest. Instability on the order of 1500-2500 J/kg of MUCAPE will
be present ahead of the mean trough with ample mid-level
perturbations ejecting into the northern tier of the CONUS during
the morning and afternoon periods. To round off the setup, a budding
140-150kt jet streak will be oriented over south-central Canada
providing a solid RER dynamic suitable for maintaining a more
organized precipitation element over the northern tier of the CONUS.
Despite the above support for convective prospects, the pattern will
be in the process of breaking down as the upper low out west becomes
a more open wave with the primary bulk of mid-level energy quickly
ejecting northeast with a textbook strong PVA to NVA signature as
the energy vacates over the northern Lakes. This setup has shifted
to a very front loaded convective scheme over the Northern Plains
into the Upper Midwest with a majority of the convective pattern
quickly ushering east-northeastward through the course of the
morning and afternoon periods. By the evening, remnant convective
elements will become more scattered in nature, eventually moving out
of the primary area of interest after nightfall leading to a
diminished threat for the end of the forecast cycle.

00z HREF EAS probs remain pretty elevated (50-80%) for at least 1"
across the eastern half of ND through Northern MN, but a sharp
decline in probs for >2" leading the case for more isolated to
widely scattered flash flood prospects in the given pattern. There
are some respectable probabilities in the neighborhood scheme for

2" within the Arrowhead of MN back over the the Dakotas (50-80%),

but again a sharp decline once into the >3" fields limiting the
upper bounds of the potential. A few areas may see between 3-5" at
the peak, but those will likely be few and far between for an area
that is actually in a low-end drought overall. Considering the soil
type and antecedent dry conditions in the region, the inherited MRGL
was maintained with little change in the risk area over the Northern
Plains into the Upper Midwest.


...Central and Southern Plains...

The Central and Southern Plains will reside within a broad warm-
sector environment positioned between a vacated warm front pressing
north through the Mississippi Valley and a slow-moving cold front
through the High Plains with a secondary cold forecast to plunge
southeast through the Northern and Central High Plains by the end of
the forecast cycle. A fairly meridional upper pattern will end up
being a key factor in the eventual ejection of stronger shortwaves
out of Chihuahua, MX, barreling northeastward through the Southern
Plains with scattered to widespread thunderstorm development along
and east of a dry line situated over West TX. The combination of
relevant buoyancy/instability positioned over the Southern and
Central U.S. coupled with favored regional ascent and
thermodynamics will create a period of late-afternoon and evening
convective development capable of localized flash flood prospects.
Recent heavy rain episodes have contributed to an elevated soil
moisture presence from the Red River Basin up through much of OK
into southeast KS, and MO. Rainfall totals up to 2-3" in a short
time frame will be capable of causing flash flooding within the
bounds of those areas that exhibit those moist top-layer soils
since the time frame for recovery will have been short. 00z HREF
neighborhood probs for >1" are respectable (50-70%) within portions
of the Central and Southern Plains with the focus generally over
north-central OK, Concho Valley, and Western Rolling Plains of West
TX. Probabilities for >2" are very low leaving the threat for
flash flooding fairly conditional and likely more reserved for more
sensitive areas within urbanized zones and areas more susceptible
due to low-water crossings.

Kleebauer


Day 2
Valid 12Z Tue Apr 29 2025 - 12Z Wed Apr 30 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN PLAINS INTO THE MISSOURI VALLEY...

Numerous flash floods, some of which may be significant, are
becoming more likely for portions of the Southern Plains on D2.=20

The synoptic pattern continues to feature ingredients that will be
supportive of an impressive rainfall event across portions of
Texas and Oklahoma on Tuesday, and potentially as far northeast as
Missouri, Illinois, Indiana, and Kentucky. The driver of this event
will be an amplifying trough reflected by a mid-level low closing
off over the Four Corners Tuesday afternoon. While there continues
to be some uncertainty as to the speed and placement of this
development, the deterministic global models have all trended
deeper with this 500mb heights over AZ/NM by 00Z Wednesday, lending
support to greater amplification of this pattern. As this low
closes off, downstream ascent will begin to intensify through
700-500mb divergence, and increasing height falls, especially later
D2 as the closed low begins to pivot more rapidly to the east.
Overlapping this ascent, secondary jet streak development emerging
from Mexico will lift meridionally into the Southern Plains, and as
some interaction of the northern and southern streams occur,
impressive upper diffluence will focus from Texas into the Mid-
Mississippi Valley, leading to even more pronounced ascent on D2.

At the same time, a cold front will be dropping southward from the
Central High Plains, but it is likely that intensifying southerly
return flow out of the Gulf will impinge this movement, leading to
a nearly stationary front much of Tuesday aligned from the Rolling
Plains of Texas E/NE towards the Bootheel of Missouri. The combined
ascent of the low-level convergence along this front and the upper
level synoptics will result in impressive and widespread lift, into
which spokes of vorticity rotating around the trough over the Four
Corners will lift periodically northeast through the period.

This pronounced ascent will act upon a region characterized by
impressive thermodynamics to support rounds of heavy rainfall. PWs
as progged by the NAEFS ensemble may exceed the 97th percentile,
which will overlap with MLCAPE of 1000-2500 J/kg to provide fuel
for thunderstorms. Storms are expected to be widespread as shown by
available simulated reflectivity from 12Z high-res CAMs, with
training from WSW to ENE likely on mean winds of 20-30 kts aligned
to the impressive instability gradient. While storms may be=20
progressive, multiple rounds are expected, and Corfidi vectors=20
aligned well to the right of the mean flow indicate that short term
training of clusters is likely.

Rainfall rates within any storms are likely to be impressive, with
HREF probabilities for 2"/hr reaching 20-30% near the Red River=20
Valley of the South, and reaching as high as 10-15% as far=20
northeast as Kentucky and Indiana, leading to stripes of=20
significant rainfall accumulations. The ECENS/SREF/GEFS 24-hr=20
probabilities all feature a low to moderate risk (10-40%) for 3+=20
inches on D2, while the HREF is much more aggressive at over 90%.=20
The ECENS/HREF overlap considerably in their footprint, but the=20
GEFS/SREF are displaced to the west, indicating at least some=20
continued spread in the axis of heavy rain. This axis will likely=20
be modified by both the frontal position and timing of any mid-=20
level shortwave impulses, but also through convective overturning=20
and modifying of the environment through the day, with modest=20
adjustment in response to differential heating boundaries that may=20
develop from clouds and moist soils. This variation is additionally
reflected by large spread in the WSE QPF plumes with minimal=20
clustering around any value, but with a trend upward overall in the
areal means.

As far as those moist soils, the NASA SPoRT 40cm soil moisture
anomaly is quite impressive, with widespread saturation above the
95th percentile from the TX Panhandle through much of the Red River
Valley of the South and into eastern OK, with percentiles above 80%
extending all the way into IL/IN/KY due to recent heavy rain the
past few days. This has compromised FFG to as low as 1.5 to 2
inches in 3 hours in some areas, which has a 30-50% chance of
exceedance according to HREF probabilities, highest across OK and
TX. It is in this area where the inherited MDT risk mostly
overlaps, and where the CSU UFVS first guess field suggests a
moderate (non UFVS has an enhanced risk area). This is also where
the EFI indicates a >70% chance of an extreme event for rainfall,
which, while impressive, is lower than what is preferred for an
increase in ERO category at this time. However, if confidence in
placement can increase, especially if that occurs atop the most
sensitive soils, a targeted high risk could be needed.=20

Downstream and to the northeast, the cold front will press more
rapidly eastward, but into a still favorable thermodynamic
environment to support fast moving storms along the front, with
rainfall rates exceeding 1"/hr at times. This has resulted in some
minor cosmetic adjustments to the inherited MRGL risk. In general,
though, the broad MRGL extending all the way through the Central=20
and Northern Ohio Valley into Northwest PA and far Southwest NY=20
was left unchanged.

Weiss


Day 3
Valid 12Z Wed Apr 30 2025 - 12Z Thu May 01 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE ARKLATEX, EASTERN OKLAHOMA, AND WESTERN OZARKS...

Another active day of convection with numerous flash floods, some
of which may be significant, is likely Wednesday across portions of
the Southern Plains and Lower to Mid Mississippi Valley.

The synoptic pattern continues to evolve in a way that is favorable
to widespread convection with training heavy rainfall across
portions of the southern and central CONUS. The primary driver for
this development is a potent mid-level trough which is progged to
move from the Four Corners Wednesday morning to the lower
Mississippi Valley Thursday morning. As this trough moves east, it
may evolve from a positive to a neutral tilt, increasing=20
downstream divergence and height falls, especially from eastern=20
TX/OK into AR/MO the latter half of D3. This ascent will be=20
enhanced by the RRQ of a strengthening and meridionally advancing=20
jet streak pivoting into the Great Lakes, leaving the strong and=20
diffluent RRQ atop the most impressive mid-level lift. Combined,=20
this will produce strong lift along and ahead of a cold front, into
which impressive convergence and moisture confluence will=20
additional help drive ascent.

This deep layer lift will impinge upon a moistening column and
low-level flow emerging from the Gulf maximizes moisture as
reflected by a PW plume above the 90th percentile according to
NAEFS translating slowly eastward through the day. As this front
and the overtopping synoptic lift move into this moistening column,
the result will be widespread showers and thunderstorms, aided by
MLCAPE that may eclipse 2000 J/kg in parts of the region. Regional
soundings indicate LIs that may climb to -6 to -10 after 00Z
Thursday, which suggests wide updrafts to limit dry air entrainment
despite the overall modest breadth of the PW plume. This suggests
that rainfall rates of 2"/hr are likely as the LLJ backs and ramps
up into TX, surging moisture northward, and setting up an
environment favorable for training and backbuilding. Where these
rain rates train, the major global ensembles all indicate at least
a 10-20% chance for 3+ inches of rain, and locally 5+ inches of
rain appears possible, although the location of the maxima vary=20
considerably at this time range.

Soil moisture across eastern TX, OK, and into southern MO is well
above normal, reflected by NASA SPoRT 40cm soil moisture anomalies
that are above 90% in many areas, and may be additionally enhanced
by rainfall in the 48-hours leading into this D3 period. This will
keep FFG marginally lowered, so any training of these intense rates
will likely result in scattered to numerous flash flooding,
especially from NE TX into far SW MO where the inherited MDT risk=20
was only adjusted cosmetically. There is some potential for the
need for an upgrade in parts of TX/OK D3, but at this time
confidence is not high enough, and this decision will be deferred
to later updates as the D1 and D2 rainfall footprints materialize.
Otherwise, D3 changes to the ERO were minor with the SLGT and MRGL
risks extending as far northeast as St Louis, MO and Cincinnati,=20
OH, respectively.

Weiss


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt= __;!!DZ3fjg!5Iag_dq6oqK6Jl-H9HWp9MbmywPlNFNk5oLLtZEP9Y-Kf2ZAI-VjWfWl_XjXRDp= RtwDyUOavAK6kSVOoNau86ECxM-8$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt= __;!!DZ3fjg!5Iag_dq6oqK6Jl-H9HWp9MbmywPlNFNk5oLLtZEP9Y-Kf2ZAI-VjWfWl_XjXRDp= RtwDyUOavAK6kSVOoNau8jnTWhaU$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt= __;!!DZ3fjg!5Iag_dq6oqK6Jl-H9HWp9MbmywPlNFNk5oLLtZEP9Y-Kf2ZAI-VjWfWl_XjXRDp= RtwDyUOavAK6kSVOoNau8QmksF3Y$=20

=3D =3D =3D
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FOUS30 KWBC 290051
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
851 PM EDT Mon Apr 28 2025

Day 1
Valid 01Z Tue Apr 29 2025 - 12Z Tue Apr 29 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE PLAINS OF THE CENTRAL UNITED STATES...

01z Update...
Maintained the inherited Slight Risk area over the South Plains
where convection was still growing upscale this evening...but
introduced two small but targeted Slight Risk areas. One of the
areas was from northern Iowa into southwestern Wisconsin where the
trailing end of a line of convection was beginning to slow forward
speed while the northern portion of the line remained progressive.
Increasing speeds of the low level jet should result in a period of
enhanced low level moisture flux convergence upon encountering the
front. The threat appears to be fairly short lived before the low
level convergence weakens. Refer to Mesoscale Precipitation
Discussion 191 for additional details. A second targeted Slight
Risk was introduced mainly across northwest Kansas where convection
has grown into a line of storms aligned with the same orientation
as the low level flow. This has already led to instances of flash
flooding across parts of northwest Kansas and the expectation is
for continued training into the early morning hours given the
quasi-stationary boundaries that the storms have focused upon.=20
Refer to Mesoscale Convective Precipitation Discussion 192 for=20
additional details here.=20

16z update...for Southern Plains...

A few 12z CAMs suggest a strong cluster/few super-cells that will
be capable of intense heavy rainfall this afternoon across portions
of KS/OK into Northwest Texas. Recent heavy rainfall in the
region, highlighted by NASA SPoRT 0-40cm saturation ratios over
70-80% and well above normal in the 90-95% percentiles suggest
little infiltration is expected even in rural locations. There
remains sufficient uncertainty to the precise latitude of these
individual cells or small clusters to have high confidence. 12z
HREF probability have increased across the most saturated areas
with greatest 1" and 2" per hour and 3-hour periods and now as high
as 30% across the most saturated areas of Southern Oklahoma. In
coordination with local forecast offices, this is sufficient
highlight a small upgrade to a Slight Risk mainly along the the Red
River into central OK where both meteorology and hydrology overlap
the most.

Gallina

~~~~Prior Discussions~~~~

...Northern Plains & Upper Midwest...

The period in question will remain active on the rainfall front, but
a few key pieces will be missing, relegating flash flood prospects
closer to the MRGL risk category as inherited from the previous
update. Upper level progression from the Inter-Mountain West through
the Northern Plains and Upper Midwest will exhibit a decaying mid to
upper level structure of a closed ULL out west with a more sheared,
progressive pieces ejecting into the High Plains and propagating
northeastward through MN and northern WI. The evolution is such that
a reasonable upper forcing pattern will materialize with scattered
to widespread convective initiation located downstream of a broad
diffluent axis situated from the Front Range through the Upper
Midwest. Instability on the order of 1500-2500 J/kg of MUCAPE will
be present ahead of the mean trough with ample mid-level
perturbations ejecting into the northern tier of the CONUS during
the morning and afternoon periods. To round off the setup, a budding
140-150kt jet streak will be oriented over south-central Canada
providing a solid RER dynamic suitable for maintaining a more
organized precipitation element over the northern tier of the CONUS.
Despite the above support for convective prospects, the pattern will
be in the process of breaking down as the upper low out west becomes
a more open wave with the primary bulk of mid-level energy quickly
ejecting northeast with a textbook strong PVA to NVA signature as
the energy vacates over the northern Lakes. This setup has shifted
to a very front loaded convective scheme over the Northern Plains
into the Upper Midwest with a majority of the convective pattern
quickly ushering east-northeastward through the course of the
morning and afternoon periods. By the evening, remnant convective
elements will become more scattered in nature, eventually moving out
of the primary area of interest after nightfall leading to a
diminished threat for the end of the forecast cycle.

00z HREF EAS probs remain pretty elevated (50-80%) for at least 1"
across the eastern half of ND through Northern MN, but a sharp
decline in probs for >2" leading the case for more isolated to
widely scattered flash flood prospects in the given pattern. There
are some respectable probabilities in the neighborhood scheme for

2" within the Arrowhead of MN back over the the Dakotas (50-80%),

but again a sharp decline once into the >3" fields limiting the
upper bounds of the potential. A few areas may see between 3-5" at
the peak, but those will likely be few and far between for an area
that is actually in a low-end drought overall. Considering the soil
type and antecedent dry conditions in the region, the inherited MRGL
was maintained with little change in the risk area over the Northern
Plains into the Upper Midwest.


...Central and Southern Plains...

The Central and Southern Plains will reside within a broad warm-
sector environment positioned between a vacated warm front pressing
north through the Mississippi Valley and a slow-moving cold front
through the High Plains with a secondary cold forecast to plunge
southeast through the Northern and Central High Plains by the end of
the forecast cycle. A fairly meridional upper pattern will end up
being a key factor in the eventual ejection of stronger shortwaves
out of Chihuahua, MX, barreling northeastward through the Southern
Plains with scattered to widespread thunderstorm development along
and east of a dry line situated over West TX. The combination of
relevant buoyancy/instability positioned over the Southern and
Central U.S. coupled with favored regional ascent and
thermodynamics will create a period of late-afternoon and evening
convective development capable of localized flash flood prospects.
Recent heavy rain episodes have contributed to an elevated soil
moisture presence from the Red River Basin up through much of OK
into southeast KS, and MO. Rainfall totals up to 2-3" in a short
time frame will be capable of causing flash flooding within the
bounds of those areas that exhibit those moist top-layer soils
since the time frame for recovery will have been short. 00z HREF
neighborhood probs for >1" are respectable (50-70%) within portions
of the Central and Southern Plains with the focus generally over
north-central OK, Concho Valley, and Western Rolling Plains of West
TX. Probabilities for >2" are very low leaving the threat for
flash flooding fairly conditional and likely more reserved for more
sensitive areas within urbanized zones and areas more susceptible
due to low-water crossings.

Kleebauer


Day 2
Valid 12Z Tue Apr 29 2025 - 12Z Wed Apr 30 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN PLAINS INTO THE MISSOURI VALLEY...

Numerous flash floods, some of which may be significant, are
becoming more likely for portions of the Southern Plains on D2.

The synoptic pattern continues to feature ingredients that will be
supportive of an impressive rainfall event across portions of
Texas and Oklahoma on Tuesday, and potentially as far northeast as
Missouri, Illinois, Indiana, and Kentucky. The driver of this event
will be an amplifying trough reflected by a mid-level low closing
off over the Four Corners Tuesday afternoon. While there continues
to be some uncertainty as to the speed and placement of this
development, the deterministic global models have all trended
deeper with this 500mb heights over AZ/NM by 00Z Wednesday, lending
support to greater amplification of this pattern. As this low
closes off, downstream ascent will begin to intensify through
700-500mb divergence, and increasing height falls, especially later
D2 as the closed low begins to pivot more rapidly to the east.
Overlapping this ascent, secondary jet streak development emerging
from Mexico will lift meridionally into the Southern Plains, and as
some interaction of the northern and southern streams occur,
impressive upper diffluence will focus from Texas into the Mid-
Mississippi Valley, leading to even more pronounced ascent on D2.

At the same time, a cold front will be dropping southward from the
Central High Plains, but it is likely that intensifying southerly
return flow out of the Gulf will impinge this movement, leading to
a nearly stationary front much of Tuesday aligned from the Rolling
Plains of Texas E/NE towards the Bootheel of Missouri. The combined
ascent of the low-level convergence along this front and the upper
level synoptics will result in impressive and widespread lift, into
which spokes of vorticity rotating around the trough over the Four
Corners will lift periodically northeast through the period.

This pronounced ascent will act upon a region characterized by
impressive thermodynamics to support rounds of heavy rainfall. PWs
as progged by the NAEFS ensemble may exceed the 97th percentile,
which will overlap with MLCAPE of 1000-2500 J/kg to provide fuel
for thunderstorms. Storms are expected to be widespread as shown by
available simulated reflectivity from 12Z high-res CAMs, with
training from WSW to ENE likely on mean winds of 20-30 kts aligned
to the impressive instability gradient. While storms may be
progressive, multiple rounds are expected, and Corfidi vectors
aligned well to the right of the mean flow indicate that short term
training of clusters is likely.

Rainfall rates within any storms are likely to be impressive, with
HREF probabilities for 2"/hr reaching 20-30% near the Red River
Valley of the South, and reaching as high as 10-15% as far
northeast as Kentucky and Indiana, leading to stripes of
significant rainfall accumulations. The ECENS/SREF/GEFS 24-hr
probabilities all feature a low to moderate risk (10-40%) for 3+
inches on D2, while the HREF is much more aggressive at over 90%.
The ECENS/HREF overlap considerably in their footprint, but the
GEFS/SREF are displaced to the west, indicating at least some
continued spread in the axis of heavy rain. This axis will likely
be modified by both the frontal position and timing of any mid-
level shortwave impulses, but also through convective overturning
and modifying of the environment through the day, with modest
adjustment in response to differential heating boundaries that may
develop from clouds and moist soils. This variation is additionally
reflected by large spread in the WSE QPF plumes with minimal
clustering around any value, but with a trend upward overall in the
areal means.

As far as those moist soils, the NASA SPoRT 40cm soil moisture
anomaly is quite impressive, with widespread saturation above the
95th percentile from the TX Panhandle through much of the Red River
Valley of the South and into eastern OK, with percentiles above 80%
extending all the way into IL/IN/KY due to recent heavy rain the
past few days. This has compromised FFG to as low as 1.5 to 2
inches in 3 hours in some areas, which has a 30-50% chance of
exceedance according to HREF probabilities, highest across OK and
TX. It is in this area where the inherited MDT risk mostly
overlaps, and where the CSU UFVS first guess field suggests a
moderate (non UFVS has an enhanced risk area). This is also where
the EFI indicates a >70% chance of an extreme event for rainfall,
which, while impressive, is lower than what is preferred for an
increase in ERO category at this time. However, if confidence in
placement can increase, especially if that occurs atop the most
sensitive soils, a targeted high risk could be needed.

Downstream and to the northeast, the cold front will press more
rapidly eastward, but into a still favorable thermodynamic
environment to support fast moving storms along the front, with
rainfall rates exceeding 1"/hr at times. This has resulted in some
minor cosmetic adjustments to the inherited MRGL risk. In general,
though, the broad MRGL extending all the way through the Central
and Northern Ohio Valley into Northwest PA and far Southwest NY
was left unchanged.

Weiss


Day 3
Valid 12Z Wed Apr 30 2025 - 12Z Thu May 01 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE ARKLATEX, EASTERN OKLAHOMA, AND WESTERN OZARKS...

Another active day of convection with numerous flash floods, some
of which may be significant, is likely Wednesday across portions of
the Southern Plains and Lower to Mid Mississippi Valley.

The synoptic pattern continues to evolve in a way that is favorable
to widespread convection with training heavy rainfall across
portions of the southern and central CONUS. The primary driver for
this development is a potent mid-level trough which is progged to
move from the Four Corners Wednesday morning to the lower
Mississippi Valley Thursday morning. As this trough moves east, it
may evolve from a positive to a neutral tilt, increasing
downstream divergence and height falls, especially from eastern
TX/OK into AR/MO the latter half of D3. This ascent will be
enhanced by the RRQ of a strengthening and meridionally advancing
jet streak pivoting into the Great Lakes, leaving the strong and
diffluent RRQ atop the most impressive mid-level lift. Combined,
this will produce strong lift along and ahead of a cold front, into
which impressive convergence and moisture confluence will
additional help drive ascent.

This deep layer lift will impinge upon a moistening column and
low-level flow emerging from the Gulf maximizes moisture as
reflected by a PW plume above the 90th percentile according to
NAEFS translating slowly eastward through the day. As this front
and the overtopping synoptic lift move into this moistening column,
the result will be widespread showers and thunderstorms, aided by
MLCAPE that may eclipse 2000 J/kg in parts of the region. Regional
soundings indicate LIs that may climb to -6 to -10 after 00Z
Thursday, which suggests wide updrafts to limit dry air entrainment
despite the overall modest breadth of the PW plume. This suggests
that rainfall rates of 2"/hr are likely as the LLJ backs and ramps
up into TX, surging moisture northward, and setting up an
environment favorable for training and backbuilding. Where these
rain rates train, the major global ensembles all indicate at least
a 10-20% chance for 3+ inches of rain, and locally 5+ inches of
rain appears possible, although the location of the maxima vary
considerably at this time range.

Soil moisture across eastern TX, OK, and into southern MO is well
above normal, reflected by NASA SPoRT 40cm soil moisture anomalies
that are above 90% in many areas, and may be additionally enhanced
by rainfall in the 48-hours leading into this D3 period. This will
keep FFG marginally lowered, so any training of these intense rates
will likely result in scattered to numerous flash flooding,
especially from NE TX into far SW MO where the inherited MDT risk
was only adjusted cosmetically. There is some potential for the
need for an upgrade in parts of TX/OK D3, but at this time
confidence is not high enough, and this decision will be deferred
to later updates as the D1 and D2 rainfall footprints materialize.
Otherwise, D3 changes to the ERO were minor with the SLGT and MRGL
risks extending as far northeast as St Louis, MO and Cincinnati,
OH, respectively.

Weiss


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt= __;!!DZ3fjg!5DVJreanRPc37Ei_qGONrRoSu0uni7pYY8mRpcvvK6hFRlGP5fxeQxo5qRCVbGU= Ey5kuex1z-k6hOra0YD6cbKLhPFA$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt= __;!!DZ3fjg!5DVJreanRPc37Ei_qGONrRoSu0uni7pYY8mRpcvvK6hFRlGP5fxeQxo5qRCVbGU= Ey5kuex1z-k6hOra0YD6clh6FmCw$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt= __;!!DZ3fjg!5DVJreanRPc37Ei_qGONrRoSu0uni7pYY8mRpcvvK6hFRlGP5fxeQxo5qRCVbGU= Ey5kuex1z-k6hOra0YD6cwe75j38$=20

=3D =3D =3D
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FOUS30 KWBC 290056
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
856 PM EDT Mon Apr 28 2025

Day 1
Valid 01Z Tue Apr 29 2025 - 12Z Tue Apr 29 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE PLAINS OF THE CENTRAL UNITED STATES...

01z Update...
Maintained the inherited Slight Risk area over the South Plains
where convection was still growing upscale this evening...but
introduced two small but targeted Slight Risk areas. One of the
areas was from Minnesota into a small portion of northern Iowa and
southwest Wisconsin where the trailing end of a line of convection
was beginning to slow forward speed while the northern portion of=20
the line remained progressive. Increasing speeds of the low level=20
jet should result in a period of enhanced low level moisture flux=20 convergence upon encountering the front. The threat appears to be=20
fairly short lived before the low level convergence weakens. Refer=20
to Mesoscale Precipitation Discussion 191 for additional details. A
second targeted Slight Risk was introduced mainly across northwest
Kansas where convection has grown into a line of storms aligned=20
with the same orientation as the low level flow. This has already=20
led to instances of flash flooding across parts of northwest Kansas
and the expectation is for continued training into the early=20
morning hours given the quasi-stationary boundaries that the storms
have focused upon. Refer to Mesoscale Convective Precipitation=20
Discussion 192 for additional details here.

16z update...for Southern Plains...

A few 12z CAMs suggest a strong cluster/few super-cells that will
be capable of intense heavy rainfall this afternoon across portions
of KS/OK into Northwest Texas. Recent heavy rainfall in the
region, highlighted by NASA SPoRT 0-40cm saturation ratios over
70-80% and well above normal in the 90-95% percentiles suggest
little infiltration is expected even in rural locations. There
remains sufficient uncertainty to the precise latitude of these
individual cells or small clusters to have high confidence. 12z
HREF probability have increased across the most saturated areas
with greatest 1" and 2" per hour and 3-hour periods and now as high
as 30% across the most saturated areas of Southern Oklahoma. In
coordination with local forecast offices, this is sufficient
highlight a small upgrade to a Slight Risk mainly along the the Red
River into central OK where both meteorology and hydrology overlap
the most.

Gallina

~~~~Prior Discussions~~~~

...Northern Plains & Upper Midwest...

The period in question will remain active on the rainfall front, but
a few key pieces will be missing, relegating flash flood prospects
closer to the MRGL risk category as inherited from the previous
update. Upper level progression from the Inter-Mountain West through
the Northern Plains and Upper Midwest will exhibit a decaying mid to
upper level structure of a closed ULL out west with a more sheared,
progressive pieces ejecting into the High Plains and propagating
northeastward through MN and northern WI. The evolution is such that
a reasonable upper forcing pattern will materialize with scattered
to widespread convective initiation located downstream of a broad
diffluent axis situated from the Front Range through the Upper
Midwest. Instability on the order of 1500-2500 J/kg of MUCAPE will
be present ahead of the mean trough with ample mid-level
perturbations ejecting into the northern tier of the CONUS during
the morning and afternoon periods. To round off the setup, a budding
140-150kt jet streak will be oriented over south-central Canada
providing a solid RER dynamic suitable for maintaining a more
organized precipitation element over the northern tier of the CONUS.
Despite the above support for convective prospects, the pattern will
be in the process of breaking down as the upper low out west becomes
a more open wave with the primary bulk of mid-level energy quickly
ejecting northeast with a textbook strong PVA to NVA signature as
the energy vacates over the northern Lakes. This setup has shifted
to a very front loaded convective scheme over the Northern Plains
into the Upper Midwest with a majority of the convective pattern
quickly ushering east-northeastward through the course of the
morning and afternoon periods. By the evening, remnant convective
elements will become more scattered in nature, eventually moving out
of the primary area of interest after nightfall leading to a
diminished threat for the end of the forecast cycle.

00z HREF EAS probs remain pretty elevated (50-80%) for at least 1"
across the eastern half of ND through Northern MN, but a sharp
decline in probs for >2" leading the case for more isolated to
widely scattered flash flood prospects in the given pattern. There
are some respectable probabilities in the neighborhood scheme for

2" within the Arrowhead of MN back over the the Dakotas (50-80%),

but again a sharp decline once into the >3" fields limiting the
upper bounds of the potential. A few areas may see between 3-5" at
the peak, but those will likely be few and far between for an area
that is actually in a low-end drought overall. Considering the soil
type and antecedent dry conditions in the region, the inherited MRGL
was maintained with little change in the risk area over the Northern
Plains into the Upper Midwest.


...Central and Southern Plains...

The Central and Southern Plains will reside within a broad warm-
sector environment positioned between a vacated warm front pressing
north through the Mississippi Valley and a slow-moving cold front
through the High Plains with a secondary cold forecast to plunge
southeast through the Northern and Central High Plains by the end of
the forecast cycle. A fairly meridional upper pattern will end up
being a key factor in the eventual ejection of stronger shortwaves
out of Chihuahua, MX, barreling northeastward through the Southern
Plains with scattered to widespread thunderstorm development along
and east of a dry line situated over West TX. The combination of
relevant buoyancy/instability positioned over the Southern and
Central U.S. coupled with favored regional ascent and
thermodynamics will create a period of late-afternoon and evening
convective development capable of localized flash flood prospects.
Recent heavy rain episodes have contributed to an elevated soil
moisture presence from the Red River Basin up through much of OK
into southeast KS, and MO. Rainfall totals up to 2-3" in a short
time frame will be capable of causing flash flooding within the
bounds of those areas that exhibit those moist top-layer soils
since the time frame for recovery will have been short. 00z HREF
neighborhood probs for >1" are respectable (50-70%) within portions
of the Central and Southern Plains with the focus generally over
north-central OK, Concho Valley, and Western Rolling Plains of West
TX. Probabilities for >2" are very low leaving the threat for
flash flooding fairly conditional and likely more reserved for more
sensitive areas within urbanized zones and areas more susceptible
due to low-water crossings.

Kleebauer


Day 2
Valid 12Z Tue Apr 29 2025 - 12Z Wed Apr 30 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN PLAINS INTO THE MISSOURI VALLEY...

Numerous flash floods, some of which may be significant, are
becoming more likely for portions of the Southern Plains on D2.

The synoptic pattern continues to feature ingredients that will be
supportive of an impressive rainfall event across portions of
Texas and Oklahoma on Tuesday, and potentially as far northeast as
Missouri, Illinois, Indiana, and Kentucky. The driver of this event
will be an amplifying trough reflected by a mid-level low closing
off over the Four Corners Tuesday afternoon. While there continues
to be some uncertainty as to the speed and placement of this
development, the deterministic global models have all trended
deeper with this 500mb heights over AZ/NM by 00Z Wednesday, lending
support to greater amplification of this pattern. As this low
closes off, downstream ascent will begin to intensify through
700-500mb divergence, and increasing height falls, especially later
D2 as the closed low begins to pivot more rapidly to the east.
Overlapping this ascent, secondary jet streak development emerging
from Mexico will lift meridionally into the Southern Plains, and as
some interaction of the northern and southern streams occur,
impressive upper diffluence will focus from Texas into the Mid-
Mississippi Valley, leading to even more pronounced ascent on D2.

At the same time, a cold front will be dropping southward from the
Central High Plains, but it is likely that intensifying southerly
return flow out of the Gulf will impinge this movement, leading to
a nearly stationary front much of Tuesday aligned from the Rolling
Plains of Texas E/NE towards the Bootheel of Missouri. The combined
ascent of the low-level convergence along this front and the upper
level synoptics will result in impressive and widespread lift, into
which spokes of vorticity rotating around the trough over the Four
Corners will lift periodically northeast through the period.

This pronounced ascent will act upon a region characterized by
impressive thermodynamics to support rounds of heavy rainfall. PWs
as progged by the NAEFS ensemble may exceed the 97th percentile,
which will overlap with MLCAPE of 1000-2500 J/kg to provide fuel
for thunderstorms. Storms are expected to be widespread as shown by
available simulated reflectivity from 12Z high-res CAMs, with
training from WSW to ENE likely on mean winds of 20-30 kts aligned
to the impressive instability gradient. While storms may be
progressive, multiple rounds are expected, and Corfidi vectors
aligned well to the right of the mean flow indicate that short term
training of clusters is likely.

Rainfall rates within any storms are likely to be impressive, with
HREF probabilities for 2"/hr reaching 20-30% near the Red River
Valley of the South, and reaching as high as 10-15% as far
northeast as Kentucky and Indiana, leading to stripes of
significant rainfall accumulations. The ECENS/SREF/GEFS 24-hr
probabilities all feature a low to moderate risk (10-40%) for 3+
inches on D2, while the HREF is much more aggressive at over 90%.
The ECENS/HREF overlap considerably in their footprint, but the
GEFS/SREF are displaced to the west, indicating at least some
continued spread in the axis of heavy rain. This axis will likely
be modified by both the frontal position and timing of any mid-
level shortwave impulses, but also through convective overturning
and modifying of the environment through the day, with modest
adjustment in response to differential heating boundaries that may
develop from clouds and moist soils. This variation is additionally
reflected by large spread in the WSE QPF plumes with minimal
clustering around any value, but with a trend upward overall in the
areal means.

As far as those moist soils, the NASA SPoRT 40cm soil moisture
anomaly is quite impressive, with widespread saturation above the
95th percentile from the TX Panhandle through much of the Red River
Valley of the South and into eastern OK, with percentiles above 80%
extending all the way into IL/IN/KY due to recent heavy rain the
past few days. This has compromised FFG to as low as 1.5 to 2
inches in 3 hours in some areas, which has a 30-50% chance of
exceedance according to HREF probabilities, highest across OK and
TX. It is in this area where the inherited MDT risk mostly
overlaps, and where the CSU UFVS first guess field suggests a
moderate (non UFVS has an enhanced risk area). This is also where
the EFI indicates a >70% chance of an extreme event for rainfall,
which, while impressive, is lower than what is preferred for an
increase in ERO category at this time. However, if confidence in
placement can increase, especially if that occurs atop the most
sensitive soils, a targeted high risk could be needed.

Downstream and to the northeast, the cold front will press more
rapidly eastward, but into a still favorable thermodynamic
environment to support fast moving storms along the front, with
rainfall rates exceeding 1"/hr at times. This has resulted in some
minor cosmetic adjustments to the inherited MRGL risk. In general,
though, the broad MRGL extending all the way through the Central
and Northern Ohio Valley into Northwest PA and far Southwest NY
was left unchanged.

Weiss


Day 3
Valid 12Z Wed Apr 30 2025 - 12Z Thu May 01 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE ARKLATEX, EASTERN OKLAHOMA, AND WESTERN OZARKS...

Another active day of convection with numerous flash floods, some
of which may be significant, is likely Wednesday across portions of
the Southern Plains and Lower to Mid Mississippi Valley.

The synoptic pattern continues to evolve in a way that is favorable
to widespread convection with training heavy rainfall across
portions of the southern and central CONUS. The primary driver for
this development is a potent mid-level trough which is progged to
move from the Four Corners Wednesday morning to the lower
Mississippi Valley Thursday morning. As this trough moves east, it
may evolve from a positive to a neutral tilt, increasing
downstream divergence and height falls, especially from eastern
TX/OK into AR/MO the latter half of D3. This ascent will be
enhanced by the RRQ of a strengthening and meridionally advancing
jet streak pivoting into the Great Lakes, leaving the strong and
diffluent RRQ atop the most impressive mid-level lift. Combined,
this will produce strong lift along and ahead of a cold front, into
which impressive convergence and moisture confluence will
additional help drive ascent.

This deep layer lift will impinge upon a moistening column and
low-level flow emerging from the Gulf maximizes moisture as
reflected by a PW plume above the 90th percentile according to
NAEFS translating slowly eastward through the day. As this front
and the overtopping synoptic lift move into this moistening column,
the result will be widespread showers and thunderstorms, aided by
MLCAPE that may eclipse 2000 J/kg in parts of the region. Regional
soundings indicate LIs that may climb to -6 to -10 after 00Z
Thursday, which suggests wide updrafts to limit dry air entrainment
despite the overall modest breadth of the PW plume. This suggests
that rainfall rates of 2"/hr are likely as the LLJ backs and ramps
up into TX, surging moisture northward, and setting up an
environment favorable for training and backbuilding. Where these
rain rates train, the major global ensembles all indicate at least
a 10-20% chance for 3+ inches of rain, and locally 5+ inches of
rain appears possible, although the location of the maxima vary
considerably at this time range.

Soil moisture across eastern TX, OK, and into southern MO is well
above normal, reflected by NASA SPoRT 40cm soil moisture anomalies
that are above 90% in many areas, and may be additionally enhanced
by rainfall in the 48-hours leading into this D3 period. This will
keep FFG marginally lowered, so any training of these intense rates
will likely result in scattered to numerous flash flooding,
especially from NE TX into far SW MO where the inherited MDT risk
was only adjusted cosmetically. There is some potential for the
need for an upgrade in parts of TX/OK D3, but at this time
confidence is not high enough, and this decision will be deferred
to later updates as the D1 and D2 rainfall footprints materialize.
Otherwise, D3 changes to the ERO were minor with the SLGT and MRGL
risks extending as far northeast as St Louis, MO and Cincinnati,
OH, respectively.

Weiss


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt= __;!!DZ3fjg!585AmR56bVEdXGJMmdplZRrEYHam7Q6Vk_SfDDLJ7Iityw4EirsWL_FDGqCtnbS= lwNVvUI4TkRWTyfmXvYPG9blKXEo$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt= __;!!DZ3fjg!585AmR56bVEdXGJMmdplZRrEYHam7Q6Vk_SfDDLJ7Iityw4EirsWL_FDGqCtnbS= lwNVvUI4TkRWTyfmXvYPG2dJnEtY$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt= __;!!DZ3fjg!585AmR56bVEdXGJMmdplZRrEYHam7Q6Vk_SfDDLJ7Iityw4EirsWL_FDGqCtnbS= lwNVvUI4TkRWTyfmXvYPGo63cdp0$=20

=3D =3D =3D
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FOUS30 KWBC 290739
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
339 AM EDT Tue Apr 29 2025

Day 1
Valid 12Z Tue Apr 29 2025 - 12Z Wed Apr 30 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
SOUTHERN PLAINS...

...Southern Plains...

A repetitive scheme of successive convective outputs across
portions of West TX through Oklahoma will result in significant
flash flooding for a large portion of the above areas. The=20
combination of several mid-level impulses ejecting northeast within
a large scale diffluent pattern will interact with a quasi-
stationary front aligned from the Western Rolling Plains of TX up
towards the Red River Basin mainly west of I-35. Favorable mid-=20
level ascent will allow for waves of convective initiation
beginning late-morning and afternoon Tuesday with a secondary pulse
around 00z Wednesday with a final pulse forecast after 06z as the
mean trough finally starts pivoting east out of the Southwestern
CONUS. Instability within the confines of West TX up to the Red
River will allow for rapid development of convective clusters with
some supercellular modes plausible prior to nightfall, eventually
merging into a more multi-cellular scheme with backbuilding favored
within the confines of the front denoted pretty well within the
theta_E gradient output in each deterministic. All CAMs are well
supportive of the 3-wave convective evolution with heavy rainfall
situated across the Southern High Plains near the eastern Permian
Basin with a general QPF maxima aligned southwest to northeast
across the northern extension of the Rolling Plains in TX, up
through the Red River and into the southern portion of the OKC
Metro. This area has been the benefactor of multiple convective
episodes already, leading to flash flooding within the corridor
extending from Lawton down to the Red River. This area will be the
most primed location for not only widespread flash flooding, but
significant life-threatening flash flood prospects due to the well
above normal soil moisture anomalies likely curbing any potential
for rainfall to soak into the top soil layer.=20

Latest 00z HREF probability fields are overwhelmingly indicative of
the threat with one of the more robust indications occurring
within the 6-hr FFG exceedance probability marker running between=20
70-90% across the area extending from Foard County in TX up to
western Cleveland County in OK. Neighborhood probabilities of >5"
total rainfall are running between 50-80% in the same location with

8" between 20-30% across Southwest OK between Lawton to the Red

River. Neighborhood probs for >3" are significant across much of OK
back into North TX with the southwest extension back into the
southeast corner of the LUB CWA. Considering the NASA SPoRT soil
moisture percentiles running between 70-99% for the 0-40cm layer
across the entire area above, the propensity for flooding, even in
rural zones will be higher than normal. Given expected rates
between 1-2"/hr during peak storm cycles and the expectation for

3" of rainfall...the threat will be of the higher magnitude in

terms of impact prospects. The previous MDT risk inherited was not
only maintained, but expanded a bit further southwest to align with
the higher probabilities with the neighborhood >5" potential and=20
the elevated HREF EAS >2" probabilities that have been depicted. A=20
high-end MDT risk is forecast across the Red River Basin west of=20
Wichita Falls up into the southern fringes of the OKC metro,=20
including the town of Norman. Lower end probabilities for flash=20
flooding will exist across areas of the eastern Permian Basin out=20
through the Concho Valley as well as across much of Oklahoma not=20
included in the MDT.=20

...Mississippi and Ohio Valleys...

Mid-level impulses that eject out of the Southern Plains will
continue to press northeast towards the Mississippi and Ohio
Valleys with a progressive cold front moving southeast out of the
Midwest during the same time frame. Afternoon destabilization
coupled with the favorable addition of mid-level forcing and surface frontogenesis will lead to scattered convective pulses across the
region with some organized elements focused within the confines of
the front and under the shortwave propagation. Soils remain moist
across much of the region extending from MO through the Ohio River
Basin with an eastern extension to the Central Appalachians and
Western PA Highlands. PWAT anomalies on the order of +1 to as high
as +2.5 deviations cements a favorable deep moist environment
conducive for heavy rainfall prospects within any convective
scheme. The greatest concentration of heavy rain will likely be
back over Southern and Central MO towards the 3 river confluence
zone near KY/MO/IN/IL. HREF probs for >1" are very high (70-90+%)
across much of the Mississippi and Ohio Valley areas with >2" probs
relatively high (50-70%) in-of the Ohio River Basin over Southern
IL through much of Eastern KY. The combination of convection over
areas that are still in recovery from previous rainfall episodes
and complex terrain will create a threat for isolated to perhaps=20
scattered flash flood instances over a large area during the
afternoon and evening hours Tuesday. A SLGT risk remains firmly in
place across much of MO along and south of I-70 until the 3 river
confluence zone referenced above. A MRGL risk encompasses all other
areas east through Western PA and even the southwest corner of NY
state.=20

Kleebauer


Day 2
Valid 12Z Wed Apr 30 2025 - 12Z Thu May 01 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE ARKLATEX, EASTERN OKLAHOMA, AND WESTERN OZARKS...

The pattern remains very active as we move into Wednesday as the
mean trough slowly slips eastward with ample mid-level energy
accompanying, creating an environment favorable for organized
convective clusters through the entire D2 time frame. Rich Gulf air
will be pulled poleward ahead of the advancing trough with several
mid-level perturbations ejecting out of the ahead of the primary
shortwave trough. This in combination with sufficient buoyancy
across Central and East TX through the Mississippi Valley will
maintain a widespread convective zone of impact with strong, heavy
thunderstorm cores and clusters capable of producing prolific
rainfall totals.=20

Two primary periods of interest have become fairly well documented
within the recent deterministic cycles. The first is the=20
continuation of the convective complex that will develop overnight=20
Tuesday into Wednesday morning over the western Red River Basin and
slowly trudge eastward as it maneuvers in tandem with the primary=20
shortwave energy, and across the remaining theta_E gradient running
parallel to the river. 00z HREF on the back end of its run is=20
signaling some very impressive rainfall totals (2-5") within the=20
first 12 hr. period in the forecast cycle (12z Wed to 00z Thu)=20
across places along the Red River up through Central and Eastern OK
as the multi-cell cluster advances. Prob fields for >3" within=20
that first 12 hrs. are between 50-90% across south-central OK,=20
along and east of the I-35 corridor with 25-40% probs for even >5".
Considering this is only for the first 12 hrs., the probs are=20
pretty impressive and really highlight the threat on the initial=20
heavy QPF core.=20

The second period of interest will occur in the afternoon and
evening hrs. as diurnally driven convection will flare up over
Eastern TX within a broad moisture rich environment as NAEFS
anomalies continue to point to +2 to +3 deviations for PWATs
(1.5-2") situated over the area. LLJ introduction by early evening
will only exacerbate the potential with increasing low-level shear
capable of persisting updrafts and eventual cell clusters that will
originate from cells moving northeast within the mean flow. Several
mid-level perturbations will be in the vicinity across Northeast TX
to truly enhance and maintain convective cores such that it becomes
a fairly favorable prospect for heavy rainfall extending into the
Lower Mississippi Valley. Totals between 2-4" within an areal
expanse are forecast across the ArkLaTex up through Western AR to
just before the MO Ozarks. Locally higher totals will be possible
across that entire area given the favorable rates between 1-2.5"/hr
forecast currently within global deterministic. Pending outflow=20
propagation within the setup, heavier totals could advance further=20
east towards Central AR, but at this juncture, the primary area of=20
focus aligns over East TX up through Eastern OK and Western AR.=20
This correlates well with the theta_E ridge extension up through=20
the area where convective threats will be highest during peak=20
diurnal destabilization and beyond.=20

The previous MDT risk was maintained with a westward extension back
over portions of south-central OK down across the Red River into
TX. The MDT risk is NOT within the DFW metro, however it does lie
just north, so will have to monitor trends closely over the next
24-36 hrs. A broad SLGT risk extends south into East TX but well
north of the TX Gulf Coast.=20

Kleebauer

Day 3
Valid 12Z Thu May 01 2025 - 12Z Fri May 02 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM PORTIONS OF
THE LOWER MISSISSIPPI VALLEY UP THROUGH THE CENTRAL AND EASTERN
GREAT LAKES...

Numerous areas of thunderstorms will develop across the Mississippi
Valley through the east-central CONUS due to the progression of a
surface low out of the Southern Plains and attendant cold front
trailing the primary cyclone. Western Atlantic ridging will allow
for a continued advection of rich Gulf air into the Eastern U.S.
with a deep moist environment pretty much solidified from the Great
Lakes down to the Gulf coast. Area PWATs will run between 1.5-2.5
deviations above normal for much of the CONUS east of the
Mississippi, an environment very favorable for convective schemes
on the eastern flank of the surface low, as well as along and ahead
of the progressing cold front. Areal QPF within the ensemble means
are generally between 0.5 and 1" with some locally higher forecast
across the above area(s). Some of the deterministic output is of
course higher with some 2-4" maxima littered over the Southeast and
Ohio Valley where the convective scheme will be most prominent.
There's little agreement within the suite on exactly where the
heaviest precip will fall, but there's plenty of coverage where any
one spot could be the beneficiary of some heavy precip. At this
lead, would probably lean on the Tennessee Valley into the Southern
Ohio Valley to have the best potential due to a combo of antecedent
moist soils, as well as the greatest surface based ascent likely
within proxy to the advancing cold front. A broad MRGl risk exists
over parts of the Lower Mississippi up through the Central and
Eastern Great Lakes with the furthest east expansion over Western
NY state down to the Central Appalachians.=20=20

Kleebauer


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt= __;!!DZ3fjg!7l9JD6txOmlpxCv5F6V-tv3FaASvVKzfmhTW4N-RgMU3yeXtbtKcl2Gx1mQcHbc= AQM4hbLtMjcaqfBsc6DLund8k_Ok$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt= __;!!DZ3fjg!7l9JD6txOmlpxCv5F6V-tv3FaASvVKzfmhTW4N-RgMU3yeXtbtKcl2Gx1mQcHbc= AQM4hbLtMjcaqfBsc6DLuTYtTOtQ$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt= __;!!DZ3fjg!7l9JD6txOmlpxCv5F6V-tv3FaASvVKzfmhTW4N-RgMU3yeXtbtKcl2Gx1mQcHbc= AQM4hbLtMjcaqfBsc6DLuanmacb8$=20

=3D =3D =3D
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FOUS30 KWBC 291555
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1155 AM EDT Tue Apr 29 2025

Day 1
Valid 16Z Tue Apr 29 2025 - 12Z Wed Apr 30 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
SOUTHERN PLAINS...

...Southern Plains...

16Z UPDATE: No major change to the reasoning outlined below, but
there was an overall trend to shift risk areas southward a bit.
Although hi-res models (even the very recent 12Z runs) are
struggling to capture ongoing convection in the region, they all do consistently show organized convection this afternoon and evening
generating fairly strong cold pools, which in turn gradually pushes
the effective front south into N TX by this evening and overnight.
This is supported by RAP analysis showing higher DCAPE values
across portions of N TX, as well as the 12Z FWD sounding which=20
revealed a layer of fairly dry air just above the boundary layer.=20
Of the available hi-res models, recent runs of the RRFS seem to=20
best represent the forward propagating bow echo in S MO and=20
additional development in SW OK. Therefore, the tweaks to the=20
positioning of the risk areas leveraged the RRFS a bit more,=20
although some deference was given to other guidance sources as=20
well. Even models that aren't handling ongoing convection very well
still indicate the development of cold pools, and the tendency for
the axis of active convection to sink south with time. This lends=20
some confidence to the overall expectations described here. The
southward progression of the effective front seems to stall
overnight, which may lead to a rainfall max in N TX, or at least=20
very close to the Red River.

PREVIOUS DISCUSSION: A repetitive scheme of successive convective=20
outputs across portions of West TX through Oklahoma will result in=20 significant flash flooding for a large portion of the above areas.=20
The combination of several mid-level impulses ejecting northeast=20
within a large scale diffluent pattern will interact with a quasi-=20 stationary front aligned from the Western Rolling Plains of TX up=20
towards the Red River Basin mainly west of I-35. Favorable mid-=20
level ascent will allow for waves of convective initiation=20
beginning late-morning and afternoon Tuesday with a secondary pulse
around 00z Wednesday with a final pulse forecast after 06z as the=20
mean trough finally starts pivoting east out of the Southwestern=20
CONUS. Instability within the confines of West TX up to the Red=20
River will allow for rapid development of convective clusters with=20
some supercellular modes plausible prior to nightfall, eventually=20
merging into a more multi-cellular scheme with backbuilding favored
within the confines of the front denoted pretty well within the=20
theta_E gradient output in each deterministic. All CAMs are well=20
supportive of the 3-wave convective evolution with heavy rainfall=20
situated across the Southern High Plains near the eastern Permian=20
Basin with a general QPF maxima aligned southwest to northeast=20
across the northern extension of the Rolling Plains in TX, up=20
through the Red River and into the southern portion of the OKC=20
Metro. This area has been the benefactor of multiple convective=20
episodes already, leading to flash flooding within the corridor=20
extending from Lawton down to the Red River. This area will be the=20
most primed location for not only widespread flash flooding, but=20
significant life-threatening flash flood prospects due to the well=20
above normal soil moisture anomalies likely curbing any potential=20
for rainfall to soak into the top soil layer.

Latest 00z HREF probability fields are overwhelmingly indicative of
the threat with one of the more robust indications occurring
within the 6-hr FFG exceedance probability marker running between
70-90% across the area extending from Foard County in TX up to
western Cleveland County in OK. Neighborhood probabilities of >5"
total rainfall are running between 50-80% in the same location with

8" between 20-30% across Southwest OK between Lawton to the Red

River. Neighborhood probs for >3" are significant across much of OK
back into North TX with the southwest extension back into the
southeast corner of the LUB CWA. Considering the NASA SPoRT soil
moisture percentiles running between 70-99% for the 0-40cm layer
across the entire area above, the propensity for flooding, even in
rural zones will be higher than normal. Given expected rates
between 1-2"/hr during peak storm cycles and the expectation for

3" of rainfall...the threat will be of the higher magnitude in

terms of impact prospects. The previous MDT risk inherited was not
only maintained, but expanded a bit further southwest to align with
the higher probabilities with the neighborhood >5" potential and
the elevated HREF EAS >2" probabilities that have been depicted. A
high-end MDT risk is forecast across the Red River Basin west of
Wichita Falls up into the southern fringes of the OKC metro,
including the town of Norman. Lower end probabilities for flash
flooding will exist across areas of the eastern Permian Basin out
through the Concho Valley as well as across much of Oklahoma not
included in the MDT.

...Mississippi and Ohio Valleys...

16Z UPDATE: No major changes were made to the risk areas here.

PREVIOUS DISCUSSION: Mid-level impulses that eject out of the=20
Southern Plains will continue to press northeast towards the=20
Mississippi and Ohio Valleys with a progressive cold front moving=20
southeast out of the Midwest during the same time frame. Afternoon=20 destabilization coupled with the favorable addition of mid-level=20
forcing and surface frontogenesis will lead to scattered convective
pulses across the region with some organized elements focused=20
within the confines of the front and under the shortwave=20
propagation. Soils remain moist across much of the region extending
from MO through the Ohio River Basin with an eastern extension to=20
the Central Appalachians and Western PA Highlands. PWAT anomalies=20
on the order of +1 to as high as +2.5 deviations cements a=20
favorable deep moist environment conducive for heavy rainfall=20
prospects within any convective scheme. The greatest concentration=20
of heavy rain will likely be back over Southern and Central MO=20
towards the 3 river confluence zone near KY/MO/IN/IL. HREF probs=20
for >1" are very high (70-90+%) across much of the Mississippi and=20
Ohio Valley areas with >2" probs relatively high (50-70%) in-of the
Ohio River Basin over Southern IL through much of Eastern KY. The=20 combination of convection over areas that are still in recovery=20
from previous rainfall episodes and complex terrain will create a=20
threat for isolated to perhaps scattered flash flood instances over
a large area during the afternoon and evening hours Tuesday. A=20
SLGT risk remains firmly in place across much of MO along and south
of I-70 until the 3 river confluence zone referenced above. A MRGL
risk encompasses all other areas east through Western PA and even=20
the southwest corner of NY state.

Lamers/Kleebauer


Day 2
Valid 12Z Wed Apr 30 2025 - 12Z Thu May 01 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE ARKLATEX, EASTERN OKLAHOMA, AND WESTERN OZARKS...

The pattern remains very active as we move into Wednesday as the
mean trough slowly slips eastward with ample mid-level energy
accompanying, creating an environment favorable for organized
convective clusters through the entire D2 time frame. Rich Gulf air
will be pulled poleward ahead of the advancing trough with several
mid-level perturbations ejecting out of the ahead of the primary
shortwave trough. This in combination with sufficient buoyancy
across Central and East TX through the Mississippi Valley will
maintain a widespread convective zone of impact with strong, heavy
thunderstorm cores and clusters capable of producing prolific
rainfall totals.

Two primary periods of interest have become fairly well documented
within the recent deterministic cycles. The first is the
continuation of the convective complex that will develop overnight
Tuesday into Wednesday morning over the western Red River Basin and
slowly trudge eastward as it maneuvers in tandem with the primary
shortwave energy, and across the remaining theta_E gradient running
parallel to the river. 00z HREF on the back end of its run is
signaling some very impressive rainfall totals (2-5") within the
first 12 hr. period in the forecast cycle (12z Wed to 00z Thu)
across places along the Red River up through Central and Eastern OK
as the multi-cell cluster advances. Prob fields for >3" within
that first 12 hrs. are between 50-90% across south-central OK,
along and east of the I-35 corridor with 25-40% probs for even >5".
Considering this is only for the first 12 hrs., the probs are
pretty impressive and really highlight the threat on the initial
heavy QPF core.

The second period of interest will occur in the afternoon and
evening hrs. as diurnally driven convection will flare up over
Eastern TX within a broad moisture rich environment as NAEFS
anomalies continue to point to +2 to +3 deviations for PWATs
(1.5-2") situated over the area. LLJ introduction by early evening
will only exacerbate the potential with increasing low-level shear
capable of persisting updrafts and eventual cell clusters that will
originate from cells moving northeast within the mean flow. Several
mid-level perturbations will be in the vicinity across Northeast TX
to truly enhance and maintain convective cores such that it becomes
a fairly favorable prospect for heavy rainfall extending into the
Lower Mississippi Valley. Totals between 2-4" within an areal
expanse are forecast across the ArkLaTex up through Western AR to
just before the MO Ozarks. Locally higher totals will be possible
across that entire area given the favorable rates between 1-2.5"/hr
forecast currently within global deterministic. Pending outflow
propagation within the setup, heavier totals could advance further
east towards Central AR, but at this juncture, the primary area of
focus aligns over East TX up through Eastern OK and Western AR.
This correlates well with the theta_E ridge extension up through
the area where convective threats will be highest during peak
diurnal destabilization and beyond.

The previous MDT risk was maintained with a westward extension back
over portions of south-central OK down across the Red River into
TX. The MDT risk is NOT within the DFW metro, however it does lie
just north, so will have to monitor trends closely over the next
24-36 hrs. A broad SLGT risk extends south into East TX but well
north of the TX Gulf Coast.

Kleebauer

Day 3
Valid 12Z Thu May 01 2025 - 12Z Fri May 02 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM PORTIONS OF
THE LOWER MISSISSIPPI VALLEY UP THROUGH THE CENTRAL AND EASTERN
GREAT LAKES...

Numerous areas of thunderstorms will develop across the Mississippi
Valley through the east-central CONUS due to the progression of a
surface low out of the Southern Plains and attendant cold front
trailing the primary cyclone. Western Atlantic ridging will allow
for a continued advection of rich Gulf air into the Eastern U.S.
with a deep moist environment pretty much solidified from the Great
Lakes down to the Gulf coast. Area PWATs will run between 1.5-2.5
deviations above normal for much of the CONUS east of the
Mississippi, an environment very favorable for convective schemes
on the eastern flank of the surface low, as well as along and ahead
of the progressing cold front. Areal QPF within the ensemble means
are generally between 0.5 and 1" with some locally higher forecast
across the above area(s). Some of the deterministic output is of
course higher with some 2-4" maxima littered over the Southeast and
Ohio Valley where the convective scheme will be most prominent.
There's little agreement within the suite on exactly where the
heaviest precip will fall, but there's plenty of coverage where any
one spot could be the beneficiary of some heavy precip. At this
lead, would probably lean on the Tennessee Valley into the Southern
Ohio Valley to have the best potential due to a combo of antecedent
moist soils, as well as the greatest surface based ascent likely
within proxy to the advancing cold front. A broad MRGl risk exists
over parts of the Lower Mississippi up through the Central and
Eastern Great Lakes with the furthest east expansion over Western
NY state down to the Central Appalachians.

Kleebauer


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt= __;!!DZ3fjg!7tQ3PjlLi7vcDP-2JEbwn4tmrucmzdQMgvz7SmBuXkGrbgdP3Owj4pvrvdsNCFI= rjm1qkrjCYlLanOITNm-okHMigN4$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt= __;!!DZ3fjg!7tQ3PjlLi7vcDP-2JEbwn4tmrucmzdQMgvz7SmBuXkGrbgdP3Owj4pvrvdsNCFI= rjm1qkrjCYlLanOITNm-oMKLuUNM$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt= __;!!DZ3fjg!7tQ3PjlLi7vcDP-2JEbwn4tmrucmzdQMgvz7SmBuXkGrbgdP3Owj4pvrvdsNCFI= rjm1qkrjCYlLanOITNm-oB_mWhUw$=20

=3D =3D =3D
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FOUS30 KWBC 292021
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
421 PM EDT Tue Apr 29 2025

Day 1
Valid 16Z Tue Apr 29 2025 - 12Z Wed Apr 30 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
SOUTHERN PLAINS...

...Southern Plains...

16Z UPDATE: No major change to the reasoning outlined below, but
there was an overall trend to shift risk areas southward a bit.
Although hi-res models (even the very recent 12Z runs) are
struggling to capture ongoing convection in the region, they all do consistently show organized convection this afternoon and evening
generating fairly strong cold pools, which in turn gradually pushes
the effective front south into N TX by this evening and overnight.
This is supported by RAP analysis showing higher DCAPE values
across portions of N TX, as well as the 12Z FWD sounding which
revealed a layer of fairly dry air just above the boundary layer.
Of the available hi-res models, recent runs of the RRFS seem to
best represent the forward propagating bow echo in S MO and
additional development in SW OK. Therefore, the tweaks to the
positioning of the risk areas leveraged the RRFS a bit more,
although some deference was given to other guidance sources as
well. Even models that aren't handling ongoing convection very well
still indicate the development of cold pools, and the tendency for
the axis of active convection to sink south with time. This lends
some confidence to the overall expectations described here. The
southward progression of the effective front seems to stall
overnight, which may lead to a rainfall max in N TX, or at least
very close to the Red River.

PREVIOUS DISCUSSION: A repetitive scheme of successive convective
outputs across portions of West TX through Oklahoma will result in
significant flash flooding for a large portion of the above areas.
The combination of several mid-level impulses ejecting northeast
within a large scale diffluent pattern will interact with a quasi-
stationary front aligned from the Western Rolling Plains of TX up
towards the Red River Basin mainly west of I-35. Favorable mid-
level ascent will allow for waves of convective initiation
beginning late-morning and afternoon Tuesday with a secondary pulse
around 00z Wednesday with a final pulse forecast after 06z as the
mean trough finally starts pivoting east out of the Southwestern
CONUS. Instability within the confines of West TX up to the Red
River will allow for rapid development of convective clusters with
some supercellular modes plausible prior to nightfall, eventually
merging into a more multi-cellular scheme with backbuilding favored
within the confines of the front denoted pretty well within the
theta_E gradient output in each deterministic. All CAMs are well
supportive of the 3-wave convective evolution with heavy rainfall
situated across the Southern High Plains near the eastern Permian
Basin with a general QPF maxima aligned southwest to northeast
across the northern extension of the Rolling Plains in TX, up
through the Red River and into the southern portion of the OKC
Metro. This area has been the benefactor of multiple convective
episodes already, leading to flash flooding within the corridor
extending from Lawton down to the Red River. This area will be the
most primed location for not only widespread flash flooding, but
significant life-threatening flash flood prospects due to the well
above normal soil moisture anomalies likely curbing any potential
for rainfall to soak into the top soil layer.

Latest 00z HREF probability fields are overwhelmingly indicative of
the threat with one of the more robust indications occurring
within the 6-hr FFG exceedance probability marker running between
70-90% across the area extending from Foard County in TX up to
western Cleveland County in OK. Neighborhood probabilities of >5"
total rainfall are running between 50-80% in the same location with

8" between 20-30% across Southwest OK between Lawton to the Red

River. Neighborhood probs for >3" are significant across much of OK
back into North TX with the southwest extension back into the
southeast corner of the LUB CWA. Considering the NASA SPoRT soil
moisture percentiles running between 70-99% for the 0-40cm layer
across the entire area above, the propensity for flooding, even in
rural zones will be higher than normal. Given expected rates
between 1-2"/hr during peak storm cycles and the expectation for

3" of rainfall...the threat will be of the higher magnitude in

terms of impact prospects. The previous MDT risk inherited was not
only maintained, but expanded a bit further southwest to align with
the higher probabilities with the neighborhood >5" potential and
the elevated HREF EAS >2" probabilities that have been depicted. A
high-end MDT risk is forecast across the Red River Basin west of
Wichita Falls up into the southern fringes of the OKC metro,
including the town of Norman. Lower end probabilities for flash
flooding will exist across areas of the eastern Permian Basin out
through the Concho Valley as well as across much of Oklahoma not
included in the MDT.

...Mississippi and Ohio Valleys...

16Z UPDATE: No major changes were made to the risk areas here.

PREVIOUS DISCUSSION: Mid-level impulses that eject out of the
Southern Plains will continue to press northeast towards the
Mississippi and Ohio Valleys with a progressive cold front moving
southeast out of the Midwest during the same time frame. Afternoon destabilization coupled with the favorable addition of mid-level
forcing and surface frontogenesis will lead to scattered convective
pulses across the region with some organized elements focused
within the confines of the front and under the shortwave
propagation. Soils remain moist across much of the region extending
from MO through the Ohio River Basin with an eastern extension to
the Central Appalachians and Western PA Highlands. PWAT anomalies
on the order of +1 to as high as +2.5 deviations cements a
favorable deep moist environment conducive for heavy rainfall
prospects within any convective scheme. The greatest concentration
of heavy rain will likely be back over Southern and Central MO
towards the 3 river confluence zone near KY/MO/IN/IL. HREF probs
for >1" are very high (70-90+%) across much of the Mississippi and
Ohio Valley areas with >2" probs relatively high (50-70%) in-of the
Ohio River Basin over Southern IL through much of Eastern KY. The
combination of convection over areas that are still in recovery
from previous rainfall episodes and complex terrain will create a
threat for isolated to perhaps scattered flash flood instances over
a large area during the afternoon and evening hours Tuesday. A
SLGT risk remains firmly in place across much of MO along and south
of I-70 until the 3 river confluence zone referenced above. A MRGL
risk encompasses all other areas east through Western PA and even
the southwest corner of NY state.

Lamers/Kleebauer


Day 2
Valid 12Z Wed Apr 30 2025 - 12Z Thu May 01 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTH-CENTRAL AND SOUTHEAST OKLAHOMA, NORTH TEXAS, AND WESTERN
ARKANSAS...

The primary change for this updated ERO for Wednesday was to
recenter the Moderate Risk further south (approx. 50 mi). This was
due to a corresponding shift in guidance, especially hi-res
guidance, but also the UKMET, CMC, and ECMWF AIFS. It also fits
with the updated expectations for the current Day 1 period, as
guidance has signaled the potential for relatively strong cold
pools reinforcing the effective front and gradually pushing it
further south. This would center it more squarely near the Red
River (OK-TX border region) or perhaps fully into N TX. There is
still some uncertainty associated with the exact convective
evolution over the 12-18 hours immediately prior to the start of
the Day 2 period, so the Moderate Risk and Slight Risk were kept
fairly broad to account for different scenarios. Nevertheless,
there was a clear enough shift in the guidance to warrant an
adjustment in the overall risk contours.

A significant flash flooding event could be ongoing at the start of
the period (~12Z Wednesday) over western North Texas and/or south-
central and southwest Oklahoma. Late tonight the southward drift of
the effective front and the associated zone of active convection
may begin to slow or stall as the low-level jet (LLJ) begins to=20
ramp up considerably over Texas. Where the nose of the LLJ sets up
relative to ongoing convection will go a long way to determining
the primary area of concern for Wednesday. Most hi-res models show
the convective cluster(s) propagating east through the morning
toward AR and N LA, with renewed development upstream over N TX by
the afternoon and another training and backbuilding configuration.

This same guidance generally supports the idea of a 24-hour
rainfall maximum in excess of 7 inches somewhere in the new
Moderate Risk area, but there is lingering uncertainty as to
precisely where that will occur. Although the probability is
currently highest in the vicinity of the Red River near where SE OK
borders N TX, it's conceivable it could occur closer to or inside
the DFW metro area. The metro area is now fully in the Moderate
Risk area with this latest update.

Some significant flash flooding will be possible as much of the
rain will likely fall in 6-12 hours and the high end amounts
produced by some of the guidance would approach or exceed a 100
year ARI for those durations. Neighborhood probabilities of
100 year ARI exceedance are not particularly high, reflecting both
the uncertainty of the exact placement of the heaviest amounts, and
that amounts well in excess of those thresholds are not currently
supported by guidance. Significant and life-threatening flash=20
flooding would be most likely in two scenarios:=20

(1) In western North Texas or south-central Oklahoma at the=20
beginning of the period, as a continuation from the previous night.
These areas have been quite wet over the past week or so, so there
is existing vulnerability to extreme rainfall. (This is more
likely.)

(2) In the Dallas-Ft. Worth metro area, as the rainfall in question
would cause serious issues in a highly urbanized area. (This is
also possible, but not certain, and highly dependent on the exact
convective evolution.)

Further north, a broad Marginal and Slight Risk area was maintained
for the Mid Mississippi Valley and Central Plains. There is some
signal for organized convection and localized heavy rainfall,
including a scattering of low probabilities of FFG exceedance, but
confidence in any specific scenario is lacking.

Lamers

Day 3
Valid 12Z Thu May 01 2025 - 12Z Fri May 02 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER A BROAD AREA
FROM THE GREAT LAKES TO MID MISSISSIPPI VALLEY TO WESTERN GULF
COAST...

An expansive plume of instability is expected to support scattered
to numerous areas of thunderstorms during the day 3 period ahead of
a surface low and trailing cold front. Machine learning
probabilities from Colorado State support the idea of a broad
Marginal Risk; this is what was inherited and it was generally
maintained. The biggest change was to extend the area southwest
through portions of Louisiana and south and southeast Texas.
Confidence in specifics is low, and the overall flash flood threat
should be limited by the fairly progressive nature of the
convection. Precipitable water values are more anomalous in the
Great Lakes region (above the 90th percentile; above 1.3 inches),
but that is also where thunderstorms should be moving the fastest.
Meanwhile, available moisture will be less anomalous further south,
in TX and LA, but thunderstorms will be moving slower. Therefore,
heavy rainfall ingredients will generally be offset across the
whole region. Hi-res models that extend out beyond 48 hours show
more significant localized rainfall maxima in TX and LA, which
makes sense given stronger instability and slower overall storm
motions. This may be where a targeted upgrade to a Slight Risk is
eventually needed.

Lamers


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt= __;!!DZ3fjg!634Zb9891iMIpx13G31Ih9Q6SwdAo3JuS6R8-hUgWsJbS_Mxerk-c_1Pqs-SOAH= hdH-pxBTRP-Ct8xew5hpAbZzAmlA$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt= __;!!DZ3fjg!634Zb9891iMIpx13G31Ih9Q6SwdAo3JuS6R8-hUgWsJbS_Mxerk-c_1Pqs-SOAH= hdH-pxBTRP-Ct8xew5hpApviFtvA$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt= __;!!DZ3fjg!634Zb9891iMIpx13G31Ih9Q6SwdAo3JuS6R8-hUgWsJbS_Mxerk-c_1Pqs-SOAH= hdH-pxBTRP-Ct8xew5hpAB3dZ2zM$=20

=3D =3D =3D
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FOUS30 KWBC 300100
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
900 PM EDT Tue Apr 29 2025

Day 1
Valid 01Z Wed Apr 30 2025 - 12Z Wed Apr 30 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
SOUTHERN PLAINS...


...Southern Plains to the Mid Mississippi Valley...
01Z Update...

Continued the southern adjustment, especially on the northern edge,
of the outlook areas extending from western Texas northeastward
across Oklahoma. Recent runs of the HRRR, as well as the 18Z HREF,
indicate multiple convective rounds training northeastward across
the region, producing several inches of rain, with numerous flash=20
floods likely across portions of the region. The latest guidance=20
shows the greatest threat extending from Northwest Texas across the
Wichita Falls area into southwestern and south-central Oklahoma --
brushing the southern extent of the OKC metro. Deterministic runs=20
of the HRRR show accumulations of 7+ inches, while the HREF shows=20
high neighborhood probabilities for accumulations of 5 inches or=20
more through the overnight across this region. The Slight and=20
Moderate Risk areas were shifted a bit farther south across the=20
southern Texas Panhandle and western Oklahoma, where limited=20
instability in the most recent analysis supports guidance=20
indicating a lesser threat for heavy rainfall rates and flash=20
flooding.

Further to the east, pulled the Marginal and the Slight Risk areas
back west of the Mississippi. Relatively drier and more stable air
is expected to persist until showers and storms now developing=20
back to the southwest spread into the region late in the period,=20
with the general model consensus showing relatively lighter amounts
and a lesser flooding threat.

...Ohio Valley to the Central Appalachians...
01Z Update...

In addition to brief heavy downpours across sensitive areas, some=20
training along the southwest flank of the storms currently moving=20
across the region may raise the threat for locally heavy rains and=20
flash flooding. But overall, storms are expected to move
progressively across the area, limiting the potential for
widespread heavy rainfall and flash flooding concerns.=20

Pereira

Day 2
Valid 12Z Wed Apr 30 2025 - 12Z Thu May 01 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTH-CENTRAL AND SOUTHEAST OKLAHOMA, NORTH TEXAS, AND WESTERN
ARKANSAS...

The primary change for this updated ERO for Wednesday was to
recenter the Moderate Risk further south (approx. 50 mi). This was
due to a corresponding shift in guidance, especially hi-res
guidance, but also the UKMET, CMC, and ECMWF AIFS. It also fits
with the updated expectations for the current Day 1 period, as
guidance has signaled the potential for relatively strong cold
pools reinforcing the effective front and gradually pushing it
further south. This would center it more squarely near the Red
River (OK-TX border region) or perhaps fully into N TX. There is
still some uncertainty associated with the exact convective
evolution over the 12-18 hours immediately prior to the start of
the Day 2 period, so the Moderate Risk and Slight Risk were kept
fairly broad to account for different scenarios. Nevertheless,
there was a clear enough shift in the guidance to warrant an
adjustment in the overall risk contours.

A significant flash flooding event could be ongoing at the start of
the period (~12Z Wednesday) over western North Texas and/or south-
central and southwest Oklahoma. Late tonight the southward drift of
the effective front and the associated zone of active convection
may begin to slow or stall as the low-level jet (LLJ) begins to
ramp up considerably over Texas. Where the nose of the LLJ sets up
relative to ongoing convection will go a long way to determining
the primary area of concern for Wednesday. Most hi-res models show
the convective cluster(s) propagating east through the morning
toward AR and N LA, with renewed development upstream over N TX by
the afternoon and another training and backbuilding configuration.

This same guidance generally supports the idea of a 24-hour
rainfall maximum in excess of 7 inches somewhere in the new
Moderate Risk area, but there is lingering uncertainty as to
precisely where that will occur. Although the probability is
currently highest in the vicinity of the Red River near where SE OK
borders N TX, it's conceivable it could occur closer to or inside
the DFW metro area. The metro area is now fully in the Moderate
Risk area with this latest update.

Some significant flash flooding will be possible as much of the
rain will likely fall in 6-12 hours and the high end amounts
produced by some of the guidance would approach or exceed a 100
year ARI for those durations. Neighborhood probabilities of
100 year ARI exceedance are not particularly high, reflecting both
the uncertainty of the exact placement of the heaviest amounts, and
that amounts well in excess of those thresholds are not currently
supported by guidance. Significant and life-threatening flash
flooding would be most likely in two scenarios:

(1) In western North Texas or south-central Oklahoma at the
beginning of the period, as a continuation from the previous night.
These areas have been quite wet over the past week or so, so there
is existing vulnerability to extreme rainfall. (This is more
likely.)

(2) In the Dallas-Ft. Worth metro area, as the rainfall in question
would cause serious issues in a highly urbanized area. (This is
also possible, but not certain, and highly dependent on the exact
convective evolution.)

Further north, a broad Marginal and Slight Risk area was maintained
for the Mid Mississippi Valley and Central Plains. There is some
signal for organized convection and localized heavy rainfall,
including a scattering of low probabilities of FFG exceedance, but
confidence in any specific scenario is lacking.

Lamers

Day 3
Valid 12Z Thu May 01 2025 - 12Z Fri May 02 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER A BROAD AREA
FROM THE GREAT LAKES TO MID MISSISSIPPI VALLEY TO WESTERN GULF
COAST...

An expansive plume of instability is expected to support scattered
to numerous areas of thunderstorms during the day 3 period ahead of
a surface low and trailing cold front. Machine learning
probabilities from Colorado State support the idea of a broad
Marginal Risk; this is what was inherited and it was generally
maintained. The biggest change was to extend the area southwest
through portions of Louisiana and south and southeast Texas.
Confidence in specifics is low, and the overall flash flood threat
should be limited by the fairly progressive nature of the
convection. Precipitable water values are more anomalous in the
Great Lakes region (above the 90th percentile; above 1.3 inches),
but that is also where thunderstorms should be moving the fastest.
Meanwhile, available moisture will be less anomalous further south,
in TX and LA, but thunderstorms will be moving slower. Therefore,
heavy rainfall ingredients will generally be offset across the
whole region. Hi-res models that extend out beyond 48 hours show
more significant localized rainfall maxima in TX and LA, which
makes sense given stronger instability and slower overall storm
motions. This may be where a targeted upgrade to a Slight Risk is
eventually needed.

Lamers


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt= __;!!DZ3fjg!-9whLZQzN1K2RbQb4fPLyt4fk4hbu55oU5N2bNKsgCQP8mLvWERMZ9Vl-8Gv8Tn= G3WleDjuE62VsInKesiH6UDexBMw$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt= __;!!DZ3fjg!-9whLZQzN1K2RbQb4fPLyt4fk4hbu55oU5N2bNKsgCQP8mLvWERMZ9Vl-8Gv8Tn= G3WleDjuE62VsInKesiH6P7qS7lo$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt= __;!!DZ3fjg!-9whLZQzN1K2RbQb4fPLyt4fk4hbu55oU5N2bNKsgCQP8mLvWERMZ9Vl-8Gv8Tn= G3WleDjuE62VsInKesiH6jiK5zZw$=20

=3D =3D =3D
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FOUS30 KWBC 300733
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
333 AM EDT Wed Apr 30 2025

Day 1
Valid 12Z Wed Apr 30 2025 - 12Z Thu May 01 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTH-CENTRAL AND SOUTHEAST OKLAHOMA, NORTH TEXAS, AND WESTERN
ARKANSAS...

The overall synoptic pattern remains unchanged in terms of the
general longwave progression as an amplified mid-level trough
begins to open up overnight and kick eastward with a strong
vorticity maxima riding the base of the mean trough. Ample mid-
level ascent within a fairly moisture rich environment thanks to
coupled LLJ advection and strong 700-500mb moisture feed from the
above trough will lead to a period of prolonged convective
maintenance and initiation over the course of Wednesday into early
Thursday morning. A strong mid-level shortwave ejection is
currently migrating eastward out of NM with WV and IR satellite
already showing instances of cooling cloud tops marking the sign of
the final wave of convective initiation off the Caprock and
adjacent Permian Basin. This expanse of convective development will
usher east-northeastward within the mean flow, also anchoring to
the quasi-stationary boundary positioned back across the Permian
Basin through the Western Rolling Plains of TX. Heavy thunderstorms=20
prior have led to a swath of very low FFG's in their wake creating
an antecedent soil moisture condition incapable of taking on much
more rainfall before causing flash flooding, some significant in
nature given the ongoing issues near the Red River.=20

As the shortwave trough migrates through North TX and the Red River
Basin, cold pool convergence during nocturnal convective cycles
will lead to a conglomeration of heavy thunderstorms extending from
Central OK down through North TX, advancing eastward within the
confines of the stationary front. By 12z Wednesday, rainfall rates
between 1-2"/hr at peak intensity will encompass a pretty large
area with the western extent of the precip footprint likely
overlapping areas that were hit recently this evening. This area
will represent the western extent of the inherited MDT risk as
outlined as 00z CAMs have come into relative agreement on the
timing of the convective cluster moving through the region in the
initial stages of the forecast cycle. The primary energy will
continue to traverse eastward with the afternoon period likely to
see the shortwave axis bisecting Southeast OK between the 18-00z
time frame. This is where the next round of convective impacts will transpire.=20

As of the latest ensemble bias corrected mean and HREF blended mean
output, the heaviest precip has shaded a bit further south compared
to run-to-run consistency, a tendency typically seen in these
setups due to the greater instability located further south, as
well as cold pool progression tending to move southeastward within
the theta_E gradient pattern(s). This is no different with a strong
signal for 2-4" areal averages located over Northeast TX with the
2" mean now even southeast of the DFW metro. 3-5" is the average
over the ArkLaTex bisecting the Red River Basin between OK/TX/LA,
something that has remained steady despite the overall shift
further south in the heavier convective forecast. This is the most
likely location for flash flood prospects, certifying the centroid
of the current MDT well-positioned and left untouched from previous forecast.=20

With the scope of the heavier precip now aligned a bit further
south to include the DFW metro and areas along I-20, the MDT was
pulled a bit further south to encompass the 00z HREF >5" neighborhood
probs of at least 30% or higher, with the general maxima located
along I-30 towards Texarkana. This correlates well with the
forecasted position of favorable PWAT anomalies +2 or better when
assessing the most recent NAEFS and ECENS outputs. Hourly rates
between 1-2"/hr will be most common at peak intensity according to
the HREF hourly prob fields with 1"/hr running between 50-90% at
any given time between 18-06z in the forecast across Northeast TX
up into Southeast OK and Western AR. 2"/hr probs are not as
prolific in the signal, but considering the sheared profile and
deep boundary layer moisture advection pattern, would not be
surprised to see some cells percolate >2"/hr given the expected
environment.

The DFW metro is one of the areas of focus due to the risk of flash
flooding being higher with the urbanization factors at hand. There
are some CAMs hinting at significant totals within the metro
proper, but some are just missing the population center to the
north and east during the overall evolution. Considering the
environmental conditioning and the nature of the heavy precip being
within a short proxy, regardless of eventual outcome the MDT risk
was sufficient to cover for the threat. HREF EAS prob fields for at
least 2" running between 30-50%, west to east across the metroplex
is a pretty good signal for the threat and that signal only
improves as you move eastward through the I-20/30 zones.=20

There is a large SLGT risk that encompasses much of the Lower
Mississippi Valley and basically the rest of the northeastern
quadrant of TX up through Central OK. Scattered to bordering
widespread convection will be forecast from the Ozarks and points
southwest with some locally enhanced cores likely to spur some
flash flood potential with low to medium grade probabilities
suggest. There's some question on the exact location of these more
isolated heavy cells, however there's some indication a secondary
maxima could be within south-central TX near the eastern flank of
the terrain east of I-35, or across MO where diffluent upper flow
will be positioned well to enhance regional convective coverage
within a fairly moist environment as the anomalous PWATs funnel
poleward.

Kleebauer


Day 2
Valid 12Z Thu May 01 2025 - 12Z Fri May 02 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER A BROAD=20
AREA FROM THE GREAT LAKES TO MID MISSISSIPPI VALLEY TO WESTERN GULF
COAST...

Surface cyclogenesis across the Southern Plains will lead to a
steady low progression to the northeast up through the Mississippi
Valley into the Great Lakes towards the end of the forecast cycle.
A cold front will trail the vacating low allowing for some frontal
convergence to occur across the above areas with the greatest=20
convective coverage likely to be within the warm sector of the Ohio
and Tennessee Valley into the southern Great Lakes. PWAT anomalies
between +2 and +3 deviations will be present for much of the CONUS
situated east of the Mississippi lending to a fairly rich=20
environment conducive for moist convective cores from the Gulf=20
coast up to the Great Lakes region. The reasoning for the heavier=20
convective threat north is the added sheared profiles within the=20
bounds of the warm sector creating better mesocyclone maturity and=20
stronger storms. All this to say....heavy rain prospects for longer
periods more likely within the zone encompassing the Tennessee and
Ohio Valleys. Current forecast totals region-wide over the=20
Southeast up into the Ohio Valley are pretty consistent with an=20
areal average between 0.5 to 1" with some locally enhanced totals=20
reaching upwards of 2-2.5" in the hardest hit locations. Given=20
rainfall rates peaking between 1-1.5"/hr when assessing the=20
probabilistic output of both the NBM and 00z HREF, there's a cap on
the higher end potential of any flash flood scenario leaving this=20
overall threat in the broad MRGL risk coverage, as inherited.=20

There is another area of interest down across the Rio Grande
extending from the Big Bend down to about Laredo for tomorrow
evening as a shortwave perturbation ejects east off of Coahuila=20
with some convection spawning over the Serranias del Burro. Some of
the CAMs are pretty significant in the overall convective
development, but much of the CAMs reach the end of their runs prior
to the activity making its way towards the Rio Grande Valley. Other deterministic and ensemble bias corrected means tell the story in
full with some respectable QPF outputs within the above bounds
leading to potentially some localized flooding within some of the
urbanized zones between Del Rio down to Laredo. Considering the
environment to be favorable and this scenario having a long history
of potential, opted to keep the MRGL risk from previous forecast
issuance to outline the threat for a quick 1-3" of rainfall with
locally higher amounts plausible pending cold pool convergence
evolutions.=20

Kleebauer


Day 3
Valid 12Z Fri May 02 2025 - 12Z Sat May 03 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS MUCH OF
CENTRAL TEXAS...

A cold front progression stemming from a trailing cold front and
pressing surface high over the Northern Plains will lead to
significant low-level convergence regime over Central TX by Friday
afternoon. Return flow around the western flank of a broad surface
ridge positioned over the Western Atlantic will reach back towards
the southern half of TX leading to a convergent pattern in
conjunction with slow-moving cold front moving north to south.
Models have been steadily increasing precip coverage within the
confines of the boundary once it makes headway into the Hill
Country of the Lone Star State by late-Friday morning, carrying
through the rest of the period as the front encounters higher
theta_E airmass within the western periphery of that surface ridge.
PWATs between +1 and +2 deviations will be present once the front
makes its presence across the region, a sufficient environment for
deep moist convective development along and ahead of the boundary
as it slowly migrates south. Ensemble means have upped precip
output in recent runs with a solid 1-2" areal average now
encompassing a large portion of the state from the Stockton
Plateau, east through Hill Country, the I-35 corridor, all the way
back towards the Piney Woods area of East TX. Favorable environment
with likely training echoes in proxy to the cold front will
generate locally enhanced QPF maxima, especially within the bounds
of the terrain where an added weak upslope component could yield
greatest results (3+" totals). The convergent pattern can be seen
as far east as the Southeastern CONUS, but the greatest surface
frontogenesis signal is situated back over the Southern Plains,
south of I-20.=20

A SLGT risk was added across the above area with a broad MRGL
encompassing the higher risk as scattered convection will still be
present up towards I-20 extending east through the Lower
Mississippi Valley up through Northern AL and Eastern TN. Will be
monitoring the setup closely as the setup will likely be most
prolific within one of the flashier areas of the country.=20

Kleebauer


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt= __;!!DZ3fjg!9dnw4QOmP0kxRSxS3tp5a_4PEkYyeWmg9-SchkFStpVdvOvqtjrOVSzD35lWtv0= 4Ih_D8WUu7PRxdrUUoJQOCiIi8j8$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt= __;!!DZ3fjg!9dnw4QOmP0kxRSxS3tp5a_4PEkYyeWmg9-SchkFStpVdvOvqtjrOVSzD35lWtv0= 4Ih_D8WUu7PRxdrUUoJQOZP0l4uI$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt= __;!!DZ3fjg!9dnw4QOmP0kxRSxS3tp5a_4PEkYyeWmg9-SchkFStpVdvOvqtjrOVSzD35lWtv0= 4Ih_D8WUu7PRxdrUUoJQOhfmWY_s$=20

=3D =3D =3D
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FOUS30 KWBC 301551
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1151 AM EDT Wed Apr 30 2025

Day 1
Valid 16Z Wed Apr 30 2025 - 12Z Thu May 01 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHEAST OKLAHOMA, NORTH TEXAS, AND WESTERN ARKANSAS...

The threat of significant flash flooding continues today, with the
focus increasingly shifting to portions of north Texas based on
observational trends and the latest 12Z hi-res model guidance.

A bowing convective line continues to advance eastward through
S OK, with a trailing line of convection extending into N TX on=20
the southern periphery of strong cold pool and mesohigh situated=20
over SC OK. Over the past couple hours, the convective line in N=20
TX has become increasingly oriented NE-SW, or even ENE-WSW; in=20
other words, more parallel to the mean flow vector. This has=20
increased the potential for training and backbuilding, especially=20
into the afternoon hours as the LLJ begins to weaken and low-level=20
winds start to veer to the southwest. For a more detailed mesoscale
analysis, please refer to MPD #202 issued at 14Z for this region.

The Moderate Risk area was maintained in SE OK and W AR, even
though confidence in flash flooding has decreased somewhat due to
the fairly steady forward progress of the bowing line, and how thin
the convective line has become. However, it was maintained out of
deference to continuity and the potential to reinvigorate the=20
convection in the next few hours with some clearing occurring ahead
of the line, which could increase rain rates again.

Greater concern now exists in N TX. The forward progression of the
line and associated cold pool in S OK and overall convective
evolution has led to far more west-east orientation to the
convective line in N TX than models had originally been
advertising. This certainly increases flash flood potential and
over the next few hours this places the Dallas-Ft. Worth metro area
squarely in the greatest risk. Hourly rainfall could exceed 2
inches per hour, with unobstructed inflow from a very moist and
unstable air mass (MLCAPE 1500-2000 j/kg with minimal CINH; PWs=20
1.6 to 1.8 inches per RAP analysis.) In an urban environment, this
could lead to significant and life-threatening flash flooding,
particularly if the rain rates are sustained for a couple hours,
which is a distinct possibility in this case.=20

As the afternoon and evening progress, the hi-res models do
indicate the potential for the southwestern periphery of the
convective line to continue to slow or stall. While they don't
necessarily agree on the specifics, many HREF members, as well as
the RRFS, indicate backbuilding and training convection could
become more likely in the corridor from Waco to Longview. This
seems to be well supported by observational trends, and in fact
many hi-res members are: (1) already not extending the convective=20
line far enough southwest based on current radar trends, and (2)
have the convective line oriented far too much in a N-S fashion.
Therefore, they may be underestimating rainfall potential a bit,
and also underselling the potential for a significant rainfall and
flash flood event further to the southwest. Probabilities and
associated risk categories were increased a bit down the I-35
corridor between DFW and AUS, and this will be monitored for
further updates based on observational trends. Rain rates in much
of C/N TX could reach or exceed 2 inches per hour given the=20
available instability and moisture.

The other biggest change for this outlook was to extend the Slight
Risk a bit further northeast through MO and into W IL based on more
elevated HREF probabilities of exceeding 1hr and 3hr flash flood
guidance and a fairly consistent signal in the guidance for a
corridor of enhanced rainfall associated with an MCV and
corresponding surface low.

Lamers


Day 2
Valid 12Z Thu May 01 2025 - 12Z Fri May 02 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER A BROAD
AREA FROM THE GREAT LAKES TO MID MISSISSIPPI VALLEY TO WESTERN GULF
COAST...

Surface cyclogenesis across the Southern Plains will lead to a
steady low progression to the northeast up through the Mississippi
Valley into the Great Lakes towards the end of the forecast cycle.
A cold front will trail the vacating low allowing for some frontal
convergence to occur across the above areas with the greatest
convective coverage likely to be within the warm sector of the Ohio
and Tennessee Valley into the southern Great Lakes. PWAT anomalies
between +2 and +3 deviations will be present for much of the CONUS
situated east of the Mississippi lending to a fairly rich
environment conducive for moist convective cores from the Gulf
coast up to the Great Lakes region. The reasoning for the heavier
convective threat north is the added sheared profiles within the
bounds of the warm sector creating better mesocyclone maturity and
stronger storms. All this to say....heavy rain prospects for longer
periods more likely within the zone encompassing the Tennessee and
Ohio Valleys. Current forecast totals region-wide over the
Southeast up into the Ohio Valley are pretty consistent with an
areal average between 0.5 to 1" with some locally enhanced totals
reaching upwards of 2-2.5" in the hardest hit locations. Given
rainfall rates peaking between 1-1.5"/hr when assessing the
probabilistic output of both the NBM and 00z HREF, there's a cap on
the higher end potential of any flash flood scenario leaving this
overall threat in the broad MRGL risk coverage, as inherited.

There is another area of interest down across the Rio Grande
extending from the Big Bend down to about Laredo for tomorrow
evening as a shortwave perturbation ejects east off of Coahuila
with some convection spawning over the Serranias del Burro. Some of
the CAMs are pretty significant in the overall convective
development, but much of the CAMs reach the end of their runs prior
to the activity making its way towards the Rio Grande Valley. Other deterministic and ensemble bias corrected means tell the story in
full with some respectable QPF outputs within the above bounds
leading to potentially some localized flooding within some of the
urbanized zones between Del Rio down to Laredo. Considering the
environment to be favorable and this scenario having a long history
of potential, opted to keep the MRGL risk from previous forecast
issuance to outline the threat for a quick 1-3" of rainfall with
locally higher amounts plausible pending cold pool convergence
evolutions.

Kleebauer


Day 3
Valid 12Z Fri May 02 2025 - 12Z Sat May 03 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS MUCH OF
CENTRAL TEXAS...

A cold front progression stemming from a trailing cold front and
pressing surface high over the Northern Plains will lead to
significant low-level convergence regime over Central TX by Friday
afternoon. Return flow around the western flank of a broad surface
ridge positioned over the Western Atlantic will reach back towards
the southern half of TX leading to a convergent pattern in
conjunction with slow-moving cold front moving north to south.
Models have been steadily increasing precip coverage within the
confines of the boundary once it makes headway into the Hill
Country of the Lone Star State by late-Friday morning, carrying
through the rest of the period as the front encounters higher
theta_E airmass within the western periphery of that surface ridge.
PWATs between +1 and +2 deviations will be present once the front
makes its presence across the region, a sufficient environment for
deep moist convective development along and ahead of the boundary
as it slowly migrates south. Ensemble means have upped precip
output in recent runs with a solid 1-2" areal average now
encompassing a large portion of the state from the Stockton
Plateau, east through Hill Country, the I-35 corridor, all the way
back towards the Piney Woods area of East TX. Favorable environment
with likely training echoes in proxy to the cold front will
generate locally enhanced QPF maxima, especially within the bounds
of the terrain where an added weak upslope component could yield
greatest results (3+" totals). The convergent pattern can be seen
as far east as the Southeastern CONUS, but the greatest surface
frontogenesis signal is situated back over the Southern Plains,
south of I-20.

A SLGT risk was added across the above area with a broad MRGL
encompassing the higher risk as scattered convection will still be
present up towards I-20 extending east through the Lower
Mississippi Valley up through Northern AL and Eastern TN. Will be
monitoring the setup closely as the setup will likely be most
prolific within one of the flashier areas of the country.

Kleebauer


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt= __;!!DZ3fjg!8JYv3_3vErz0562OCSAEyf0IRviJoNKVNSAOQ7-SPDNf-KLySIzJD7gIqnh1aUz= ihIjriYSQxTMaCJF4DosR2jry334$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt= __;!!DZ3fjg!8JYv3_3vErz0562OCSAEyf0IRviJoNKVNSAOQ7-SPDNf-KLySIzJD7gIqnh1aUz= ihIjriYSQxTMaCJF4DosRbc3geoU$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt= __;!!DZ3fjg!8JYv3_3vErz0562OCSAEyf0IRviJoNKVNSAOQ7-SPDNf-KLySIzJD7gIqnh1aUz= ihIjriYSQxTMaCJF4DosRPURawxg$=20

=3D =3D =3D
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FOUS30 KWBC 302017
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
417 PM EDT Wed Apr 30 2025

Day 1
Valid 16Z Wed Apr 30 2025 - 12Z Thu May 01 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHEAST OKLAHOMA, NORTH TEXAS, AND WESTERN ARKANSAS...

The threat of significant flash flooding continues today, with the
focus increasingly shifting to portions of north Texas based on
observational trends and the latest 12Z hi-res model guidance.

A bowing convective line continues to advance eastward through
S OK, with a trailing line of convection extending into N TX on
the southern periphery of strong cold pool and mesohigh situated
over SC OK. Over the past couple hours, the convective line in N
TX has become increasingly oriented NE-SW, or even ENE-WSW; in
other words, more parallel to the mean flow vector. This has
increased the potential for training and backbuilding, especially
into the afternoon hours as the LLJ begins to weaken and low-level
winds start to veer to the southwest. For a more detailed mesoscale
analysis, please refer to MPD #202 issued at 14Z for this region.

The Moderate Risk area was maintained in SE OK and W AR, even
though confidence in flash flooding has decreased somewhat due to
the fairly steady forward progress of the bowing line, and how thin
the convective line has become. However, it was maintained out of
deference to continuity and the potential to reinvigorate the
convection in the next few hours with some clearing occurring ahead
of the line, which could increase rain rates again.

Greater concern now exists in N TX. The forward progression of the
line and associated cold pool in S OK and overall convective
evolution has led to far more west-east orientation to the
convective line in N TX than models had originally been
advertising. This certainly increases flash flood potential and
over the next few hours this places the Dallas-Ft. Worth metro area
squarely in the greatest risk. Hourly rainfall could exceed 2
inches per hour, with unobstructed inflow from a very moist and
unstable air mass (MLCAPE 1500-2000 j/kg with minimal CINH; PWs
1.6 to 1.8 inches per RAP analysis.) In an urban environment, this
could lead to significant and life-threatening flash flooding,
particularly if the rain rates are sustained for a couple hours,
which is a distinct possibility in this case.

As the afternoon and evening progress, the hi-res models do
indicate the potential for the southwestern periphery of the
convective line to continue to slow or stall. While they don't
necessarily agree on the specifics, many HREF members, as well as
the RRFS, indicate backbuilding and training convection could
become more likely in the corridor from Waco to Longview. This
seems to be well supported by observational trends, and in fact
many hi-res members are: (1) already not extending the convective
line far enough southwest based on current radar trends, and (2)
have the convective line oriented far too much in a N-S fashion.
Therefore, they may be underestimating rainfall potential a bit,
and also underselling the potential for a significant rainfall and
flash flood event further to the southwest. Probabilities and
associated risk categories were increased a bit down the I-35
corridor between DFW and AUS, and this will be monitored for
further updates based on observational trends. Rain rates in much
of C/N TX could reach or exceed 2 inches per hour given the
available instability and moisture.

The other biggest change for this outlook was to extend the Slight
Risk a bit further northeast through MO and into W IL based on more
elevated HREF probabilities of exceeding 1hr and 3hr flash flood
guidance and a fairly consistent signal in the guidance for a
corridor of enhanced rainfall associated with an MCV and
corresponding surface low.

Lamers


Day 2
Valid 12Z Thu May 01 2025 - 12Z Fri May 02 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN SOUTHERN
OKLAHOMA, FAR NORTH TEXAS, AND FAR WESTERN ARKANSAS...

The most significant change for this outlook period was to
introduce a Slight Risk primarily over southern Oklahoma, where
previously the probabilities were below the Marginal Risk (5
percent) threshold. This was due to an emerging consensus in model
guidance that thunderstorms will blossom on Thursday Night ahead of
a digging shortwave in an area of relatively strong upper level
divergence. Although the mid levels will be drier than in recent
days, leading to lower PWs overall, strong instability will be in=20
place which should support organized convection with more intense=20
rain rates at times. A key uncertainty at the moment is the overall
structure of convective clusters and lines, and whether they will=20
be more progressive or include some training. However, the=20
potential for heavy rain rates in an area that has received a lot=20
of rainfall already in recent days does raise the risk of flash
flooding. Hourly rainfall on the order of 1-2 inches will be
possible in this environment, and in areas with already wet ground
conditions this would be more than sufficient to cause flash
flooding.

Elsewhere, the broad Marginal Risk that was already in place was
maintained with few changes. A broad plume of moderate to strong
instability will favor scattered lines and clusters of
thunderstorms in advance of a surface low and trailing cold front
with fairly high instantaneous rain rates. The key uncertainty
would be the persistence of those rain rates and the degree to
which any training could occur, but the overall environment with
PWs around 1.3 to 1.4 inches raises the probability high enough to
warrant the broad Marginal Risk. The only exception to the
continuation of the risk area was over much of IL, IN, and MI,
which should largely be behind the cold front by 18Z and so most of
the QPF on model guidance would be associated with post-frontal
showers that would tend to have lower rain rates overall.

Lamers


Day 3
Valid 12Z Fri May 02 2025 - 12Z Sat May 03 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS FROM THE
SOUTHERN PLAINS INTO THE LOWER MISSISSIPPI VALLEY...

A flash flood event may be ongoing at the beginning of the period,
with convection developing on Thursday Night in southern Oklahoma
and continuing into Friday morning. This may continue beyond 12Z
Friday (into this Day 3 period) in SE OK and AR in the region of
strong upper-level divergence. The existing Slight Risk over TX was
expanded northward to account for this scenario. Whether that round
of convection wanes due to more extensive cloud cover and limited
daytime heating, or progresses southeast and becomes reinvigorated
during the afternoon, the threat of heavy rainfall and flash
flooding should expand southeast on Friday into the Lower
Mississippi Valley (S AR, N LA, W MS) and much of C and E TX. This
would be via progression of the early round of storms, or
redevelopment in the afternoon and evening hours.=20

Strong instability will remain over much of the warm sector with=20
CAPE values potentially in excess of 3000 j/kg in some areas, and=20
PW values are expected to increase above 1.5 inches as SSE flow=20
increases off the Gulf. The combination of strong instability and=20
high PWs will favor very heavy rain rates in organized convection,
and this is supportive of the broad Slight Risk on the new=20
outlook. At the moment, model guidance is showing the most=20
consistent signal for heavy rain from Texas Hill Country in C TX=20
east- northeast into the Piney Woods region of E TX. Given the=20
overall environment, it is possible an upgrade to a Moderate Risk=20
may be needed at some point.

Lamers


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt= __;!!DZ3fjg!6xRxQekbUzFBT0Qg_LxjCsF7ZP3yAmkoM8lbioY-aLmehrj-mYvjVklzNW85PXg= 3fMYSpxyelbZpIe-AyurHgrfoRgw$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt= __;!!DZ3fjg!6xRxQekbUzFBT0Qg_LxjCsF7ZP3yAmkoM8lbioY-aLmehrj-mYvjVklzNW85PXg= 3fMYSpxyelbZpIe-AyurHrhh3wFU$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt= __;!!DZ3fjg!6xRxQekbUzFBT0Qg_LxjCsF7ZP3yAmkoM8lbioY-aLmehrj-mYvjVklzNW85PXg= 3fMYSpxyelbZpIe-AyurHnQq4WZ4$=20

=3D =3D =3D
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