ACUS48 KWNS 220813
SWOD48
SPC AC 220812

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0312 AM CDT Tue Apr 22 2025

Valid 251200Z - 301200Z

...DISCUSSION...
...Days 4-5/Fri-Sat -- Central/Southern Plains...

An upper ridge will build over the Plains toward the MS Valley this
weekend as a deepening upper trough develops over the western U.S.
Some lead shortwave impulses will likely migrate through the ridge,
and southwesterly flow increases over the central/southern Rockies.
At the surface, persistent south/southeasterly low-level flow will
maintain a warm advection regime across the southern/central Plains,
while a daily surface dryline evolves over the High Plains. While
some severe potential may occur Friday and Saturday over parts the central/southern Plains, uncertainty remains quite high given
several periods of convection leading into Friday, as well as
ongoing convection Friday morning, and possible capping concerns
beneath the upper ridge both days. This precludes 15 percent
probability delineation at this time, but probabilities may be
needed in subsequent outlooks as smaller scale details become better
resolved.

...Days 6-8/Sun-Tue -- Great Plains to the Upper Midwest...

A more active severe weather period is possible early next week as
the western U.S. trough develops eastward into the Plains and Great
Lakes vicinity. The upper trough may begin ejecting into the
southern/central Plains as early as Day 6/Sun. However, the timing
of this feature may be ill-timed with peak diurnal
heating/destabilization such that stronger large-scale ascent and
increasing southwesterly flow aloft arrive overnight. Forecast
soundings Sunday afternoon suggest capping may limit convection.

By Day 7/Mon, a strong midlevel jet streak should overspread
portions of the central/southern Plains into the Upper Midwest. Lee cyclogenesis is forecast across the central High Plains, resulting
in a sharpening dryline across portions of the Great Plains, and
warm front extending across the eastern Dakotas to the Mid-MS
Valley. Rich Gulf moisture will be in place across the warm sector
and widely scattered severe storms appear possible from Monday
afternoon into Monday night. As is typical at longer time frames,
forecast guidance differs in exact timing and placement of key
features. However, the overall pattern is favorable for an
all-hazards severe weather episode, and a 15 percent delineation has
been included, though this area may shift over the coming days as
details become better resolved.

Severe potential may continue into Day 8/Tue across portions of the
Midwest to the southern Plains as a shortwave upper trough continues
across the Great Lakes into southeast Canada, and a cold front
impinges southeastward over portions of the region. Uncertainty
increases considerably during this time, precluding 15 percent
probabilities at this time.

..Leitman.. 04/22/2025

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ACUS48 KWNS 230817
SWOD48
SPC AC 230815

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0315 AM CDT Wed Apr 23 2025

Valid 261200Z - 011200Z

...DISCUSSION...
...Days 5-7/Sun-Tue -- Great Plains to the Midwest...

Forecast guidance is in good agreement that a deepening upper trough
over the western states will eject eastward across the Plains and
Midwest early next week. Beginning Day 5/Sun, the upper trough will
extend from the central Rockies to the Southwest, with a belt of
strong southeasterly flow emerging over the central/southern High
Plains Sunday night. Surface lee low development is forecast over
the northern/central Plains Sunday afternoon, with the low moving
into SD/NE by Monday morning. Southerly low-level flow will
transport ample moisture northward across the Plains and Mid-MO
Valley on Sunday, with a sharpening dryline extending southward from
western NE into western TX. Some severe potential could develop
along the dryline and near the surface low/triple point. However,
forecast soundings maintain strong capping and any convective
development could be rather sparse. For now, this will preclude
severe probabilities for Day 5/Sun.

On Day 6/Mon, the upper trough will continue eastward, moving into
the Plains by Tuesday morning. Ahead of the trough, a belt of strong southwesterly flow aloft will extend from OK into the Upper Midwest.
A deepening surface low over SD will shift east/northeast through
the period, with a trailing cold front shifting east/southeast
across the Plains. Rich boundary layer moisture within a moderate to
strongly unstable airmass and favorable shear parameter space will
support an all-hazards severe weather episode across a fairly broad
area from OK to MN/WI Monday afternoon into Monday night.

Severe potential is likely to continue into Day 7/Tue, though some
differences within medium range guidance with the evolution of the
upper trough and key surface features does result in a bit more
uncertainty compared to Monday, especially on the eastward extent of
severe potential. Nevertheless, strong forcing atop a broad warm
sector ahead of an eastward advancing cold front will continue to
support severe potential from northeast Texas into Lower MI.

..Leitman.. 04/23/2025

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ACUS48 KWNS 240848
SWOD48
SPC AC 240847

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0347 AM CDT Thu Apr 24 2025

Valid 271200Z - 021200Z

...DISCUSSION...
...Day 4/Sun - Great Plains...

An upper trough over the southwestern U.S. early Sunday will develop
east, becoming oriented from the central Rockies to the Lower CO
Valley by Monday morning. As the trough develops east, a band of
enhanced southwesterly mid/upper flow will overspread NM northeast
to the Dakotas. A lee surface cyclone will deepen over western
SD/NE, eventually shifting east into eastern SD by early Monday.
Southerly low-level flow will transport Gulf moisture northward
across the Plains as a dryline sharpens over western portions of the
Plains. An EML should limit diurnal thunderstorm activity, though an
isolated supercell can not be ruled out somewhere along the dryline
from western SD southward into west TX. As a 50-60 kt low-level jet
develops overnight, elevated convection may develop near the surface
low over parts of SD/ND. This activity could pose a risk for hail,
but uncertainty precludes 15 percent probabilities at this time.

...Day 5/Mon - Southern Plains to Upper Midwest...

A shortwave trough embedded within the larger-scale western U.S.
upper trough will eject from the central Rockies to the Upper
Midwest on Monday. The southern branch of the western upper trough
will stall over the Four Corners vicinity, but a broad swath of
50-80 kt 500 mb southwesterly flow will extend from the southern
Plains to the upper Great Lakes. A surface low will shift east
across the Upper MS Valley, with a trailing cold front moving across
the northern/central Plains into WI/IA during the afternoon and
overnight hours. A dryline also will extend southwest from
northeast/central KS into western OK/northwest TX.

Rich Gulf moisture will be transported northward on increasing
southerly low-level flow ahead of the aforementioned surface
features. Moderate to strong destabilization is forecast from OK
northeast into IA and adjacent parts of southern MN/southwest WI.
Supercell wind profiles amid this very moist/unstable airmass will
support an all-hazards severe risk. The greatest risk should be
centered on IA and adjacent areas from extreme northeast KS into
southeast MN/southwest WI, where an intense low-level jet is
expected to develop by late afternoon/early evening.

With southwest extent across eastern KS into OK, and northwest TX,
convective coverage is less certain as capping my limit severe
thunderstorm development. Current model trends hanging back the
southern branch of the upper trough also suggests large-scale ascent
will be weaker across the region, resulting in a more difficult time
overcoming capping. Higher probabilities may be needed in subsequent
outlooks if trends suggest capping will be less of a hindrance.

...Day 6/Tue - North TX into southern Lower MI and OH...

Severe potential will continue into Tuesday, especially from the
Mid-MS Valley into Lower MI/OH where the surface cold front is
expected to continue pushing east/southeast through the period.
While the upper shortwave trough over the Great Lakes will deamplify
through the day, enhanced southwesterly flow atop the frontal
boundary and a moist/unstable airmass should continue to support
severe thunderstorm organization in the form of clusters and line
segments.

With southwest extent into AR/eastern OK/north TX, large-scale
ascent will become weaker. However, persistent warm advection in the
vicinity of a stalled boundary, and potential secondary surface low
development should foster strong/severe thunderstorm activity.

...Days 7-8/Wed-Thu... OK/TX into the Lower MS Valley...

Forecast guidance shows the southwestern U.S. upper trough ejecting
across the southern Plains and Lower MS Valley by the end of the
forecast period. This could bring severe thunderstorm potential to
these regions (OK/TX on Wed, ArkLaTex/Lower MS Valley on Thu).
However, several periods of thunderstorm activity leading into
Wednesday and large surface pattern differences among medium range
guidance precludes introduction of severe probabilities at this
time.

..Leitman.. 04/24/2025

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ACUS48 KWNS 250856
SWOD48
SPC AC 250854

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0354 AM CDT Fri Apr 25 2025

Valid 281200Z - 031200Z

...DISCUSSION...
...Day 4/Mon - Southern Plains to Upper Midwest...
A strong mid-level jet streak will move rapidly northeastward from
the Southwest to the Upper Midwest on Monday. As this occurs, a
surface low will deepen and move from the northern Plains to the
northern Great Lakes. Strong southwesterly lower tropospheric flow
will advect high theta-e air northward across the Midwest and into
parts of the Upper Midwest. Broken to scattered cloudcover will
support surface heating and strong destabilization across the warm
sector from southeast Minnesota and western Wisconsin to the
southern Plains. Isolated to scattered supercells are likely along
the dryline which will extend from the southern Plains and into
Kansas.

The greatest focus for severe weather on Monday will be from eastern
Kansas into northern Missouri, much of Iowa and into southern
Minnesota and western Wisconsin. Moderate to strong instability,
strong shear, and increasing forcing for ascent supports the
potential for numerous rounds of severe thunderstorms. The wind
profile supports supercells capable of all severe weather hazards
including the potential for strong tornadoes.

...Day 5/Tue - Southern Plains to parts of the Northeast...
The surface low associated with the Day 4 threat will continue
northeast and bring its associated cold front eastward across the
Midwest and Great Lakes through the day Tuesday. Moderate to strong
instability is forecast south of this front from northern New York
to the Ohio Valley. Much of the frontal zone should have sufficient
shear to support multiple storm clusters and the potential for a few supercells.

Day 6/Wed-Day8/Fri - Portions of the Mid-Mississippi Valley into the Southeast...
A weaker mid-level shortwave trough is consistently depicted by
extended range guidance by the middle of next week across the
southern Plains. However, significant uncertainty remains about the
strength of this trough and location of any frontal zones. In
addition, convection across the southern Plains each day of the
extended range forecast could significantly impact destabilization
by Day 6-8. Therefore, confidence is not high enough to add
probabilities at this time, but they may eventually be needed
somewhere across the Southeast/Mid Mississippi Valley.

..Bentley.. 04/25/2025

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ACUS48 KWNS 260849
SWOD48
SPC AC 260848

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0348 AM CDT Sat Apr 26 2025

Valid 291200Z - 041200Z

...DISCUSSION...
...Day 4/Tuesday - West Texas to the Northeast...
Moderate instability will be present along an elongated frontal zone
from the southern Plains to the Northeast on Tuesday. Modest shear
along the frontal zone will support some organization into multicell
clusters and perhaps supercells. A greater severe weather threat
will exist across the eastern Great Lakes where forcing and shear
will be strongest as a 75 knot mid-level jet streak crosses southern
Ontario.

Another focused zone of greater coverage of severe storms will be
across parts of West Texas where multiple rounds of storm are
anticipated. The first chance of storms will be during the afternoon
as the front continues to move south across Oklahoma and perhaps
into North Texas. An additional round of storms will be possible
across parts of West Texas as the low-level jet strengthens Tuesday
night in the presence of strong instability and shear.

...Day 5/Wednesday - North Texas to the ArkLaTex...
Ongoing Day 4 convection may have some impact on the exact location
of the severe weather threat on Tuesday. However, regardless of Day
4 convective evolution, there will likely be a region with a more
focused severe weather threat on Day 5/Wednesday where moderate to
strong instability exists ahead of strengthening mid-level flow and
a mid-level trough which will move across the southern Plains. 15% probabilities have been added for Day 5 from North Texas to the
ArkLaTex where this location of greatest severe weather threat
appears most likely at this time.

..Bentley.. 04/26/2025

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ACUS48 KWNS 270723
SWOD48
SPC AC 270721

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0221 AM CDT Sun Apr 27 2025

Valid 301200Z - 051200Z

...DISCUSSION...
...Day 4/Wednesday - North Central to Northeast Texas...
A mid-level trough will eject across the southern Plains on Day
4/Wednesday. Forecast guidance still shows some timing difference
which affect the location of the surface low and thus the region of
the greatest severe weather threat. However, at this time, the area
along and south of the Red River to east-central Texas remains the
most likely location to receive some severe weather regardless of
the exact solution.

Moderate instability and an uncapped environment will support storm
development during the day on Wednesday. At this time, it appears
widespread convection amid a very moist profile could result in HP
storms in close proximity with eventual growth into a MCS. Forecast
soundings show favorable low-level shear which would support some
tornado threat. However, the aforementioned storm mode concerns
could limit this threat despite the favorable wind profile.

...Day 5/Thursday - Mid Mississippi Valley...
As a mid-level trough advances from the southern Plains to the Great
Lakes on Thursday, a surface low will also develop and continue
northeast. The strength and location of this surface low are
uncertain at this time due to differing evolution of the mid-level
pattern. Warm-sector destabilization also remains highly variable.
If a solution such as the GFS solution verifies, then a greater
severe weather threat will likely exist across parts of Tennessee
and northern AL/MS into parts of the Ohio Valley. However, if the
ECMWF instability verifies, the likelihood of widespread severe
weather goes down significantly. No probabilities have been added
for Day 5 yet, but if details become more clear and favorable,
probabilities may eventually be needed.

..Bentley.. 04/27/2025

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ACUS48 KWNS 280837
SWOD48
SPC AC 280835

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0335 AM CDT Mon Apr 28 2025

Valid 011200Z - 061200Z

...DISCUSSION...
The extended period will begin with broad troughing across the
eastern US and a surface low tracking northeastward across the Great
Lakes. A cold front will stretch from the northeastern US southward
into the southern Plains, shifting eastward on D5/Friday across the
Ohio Valley into the southeastern US. Beyond D5/Friday, heights will
begin to rise across the Plains as an upper level high strengthens,
which will limit the severe threat through the end of the extended.

...D5/Friday - Tennessee and Ohio Valley...
On D5/Friday, thunderstorm development is expected along the cold
front across portions of the Ohio Valley into the southern
Mississippi Valley. Model solutions differ on how much instability
will be available across Tennessee into the Ohio Valley, where the
strongest flow aloft will reside. There appears to be little overlap
between the better flow aloft and any meaningful instability, which
keeps probabilities too low to include areas in the extended.
However, some instances of wind and hail from stronger storms will
be possible across portions of Tennessee into Ohio.

...D6/Saturday - Southwest Texas...
Thunderstorm development is possible along the dryline in
southwestern Texas on D6/Saturday. During this period, heights aloft
will be rising, which will likely work to limit overall coverage of thunderstorm activity. Nonetheless, a few isolated supercells may
develop with potential for large hail and severe wind. Overall,
limited coverage does not warrant inclusion of probabilities.

..Thornton/Bentley.. 04/28/2025

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ACUS48 KWNS 280858
SWOD48
SPC AC 280857

Day 4-8 Convective Outlook CORR 1
NWS Storm Prediction Center Norman OK
0357 AM CDT Mon Apr 28 2025

Valid 011200Z - 061200Z

CORRECTED FOR INCORRECT DAY REFERENCE

...DISCUSSION...
The extended period will begin with broad troughing across the
eastern US and a surface low tracking northeastward across the Great
Lakes. A cold front will stretch from the northeastern US southward
into the southern Plains, shifting eastward on D4/Thursday across
the Ohio Valley into the southeastern US. Beyond D4/Thursday,
heights will begin to rise across the Plains as an upper level high strengthens, which will limit the severe threat through the end of
the extended.

...D4/Thursday - Tennessee and Ohio Valley...
On D4/Thursday, thunderstorm development is expected along the cold
front across portions of the Ohio Valley into the southern
Mississippi Valley. Model solutions differ on how much instability
will be available across Tennessee into the Ohio Valley, where the
strongest flow aloft will reside. There appears to be little overlap
between the better flow aloft and any meaningful instability, which
keeps probabilities too low to include areas in the extended.
However, some instances of wind and hail from stronger storms will
be possible across portions of Tennessee into Ohio.

...D5/Friday - Southwest Texas...
Thunderstorm development is possible along the dryline in
southwestern Texas on D5/Friday. During this period, heights aloft
will be rising, which will likely work to limit overall coverage of thunderstorm activity. Nonetheless, a few isolated supercells may
develop with potential for large hail and severe wind. Overall,
limited coverage does not warrant inclusion of probabilities.

..Thornton/Bentley.. 04/28/2025

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ACUS48 KWNS 290856
SWOD48
SPC AC 290854

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0354 AM CDT Tue Apr 29 2025

Valid 021200Z - 071200Z

...DISCUSSION...
The severe potential remains limited through the day 4-8 period. On
D4/Friday, an upper level trough will be located across the eastern
US with strengthening upper level ridging across the western US into
the Rockies. Along the dryline in far western Texas, a few
thunderstorms capable of large hail will be possible. This threat
may be limited in duration and coverage by the southward moving cold
front expected to extend from the southern Plains into the
northeastern US. As this front shifts southward and a surface high
builds in across the central US D5/Saturday into D6/Sunday, moisture
will be scoured out of much of the CONUS limiting the severe threat.


As the surface high shifts eastward across the Midwest, slow
moisture return will begin across the southern Plains late D6/Sunday
into D7/Monday. During this period, the next upper-level wave will
be deepening across the western US. As this system evolves, severe
potential may return late in the period across portions of the
southern and central Plains.

..Thornton/Bentley.. 04/29/2025

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ACUS48 KWNS 300805
SWOD48
SPC AC 300803

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0303 AM CDT Wed Apr 30 2025

Valid 031200Z - 081200Z

...DISCUSSION...
A cold front will shift southward across the southern US at the
start of the extended period, scouring out much of the moisture
across the CONUS. An upper level ridge is expected to strengthen
across the central US while weak troughing continues in the
northeast. This pattern will limit severe potential across the CONUS
through the weekend.

As a surface high across the Plains strengthens and shifts eastward
into the Midwest, return flow from the Gulf will bring moisture back
in across the central and southern Plains starting D6/Monday. A
trough will strengthen across the western US D5/Sunday before
ejecting into the Plains sometime D7/Tuesday into D8/Wednesday. This
would likely bring a return to chances for severe storms across some
portion of the southern and central Plains. There is uncertainty in
how far northward moisture return will reach and where exactly
surface features will be during this time period. This precludes the
need to include areas at this time.

..Thornton/Bentley.. 04/30/2025

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ACUS48 KWNS 010856
SWOD48
SPC AC 010855

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0355 AM CDT Thu May 01 2025

Valid 041200Z - 091200Z

...DISCUSSION...
High pressure will dominate much of the eastern CONUS at the start
of the extended period. This will shift most moisture into the
Atlantic/Gulf of America. The only exception will be across Texas
where east-southeasterly flow will advect richer low-level moisture
into the southern High Plains. This will be the focus for any
potential severe storms on Day 4/Sun and Day 5/Mon. However,
specific during this period, and particularly beyond, are quite
nebulous. The ECMWF cuts off an upper low across the Ohio Valley
vicinity on Saturday Night while the GFS waits to cut off the
upper-low across the Southeast US on Monday/Tuesday.

Farther west there is more consistency in the upper pattern with a
cutoff low in the Southwest vicinity. Enhanced southwesterly flow
could result in several days of severe weather in the southern
Plains. However, moisture remains uncertain due to aforementioned timing/location differences for the mid-level trough in the East.
The GFS solution results in a more progressive cold front which
clears out most of the greater moisture from the Gulf. However, the
ECMWF stalls the front across the central Gulf which leaves a
reservoir of rich theta-e which can be advected across Texas and
vicinity during the early-mid part of next week. Therefore,
predictability remains too low for probabilities at this time, but
once the upper-level pattern becomes more clear, probabilities may
be necessary.

..Bentley.. 05/01/2025

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ACUS48 KWNS 020845
SWOD48
SPC AC 020844

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0344 AM CDT Fri May 02 2025

Valid 051200Z - 101200Z

...DISCUSSION...
...Day 4/Monday - Southern High Plains...
Lee cyclogenesis will strengthen on Monday in the southern High
Plains as a mid-level trough advects eastward. As this occurs, rich
low-level moisture will advect into West Texas which will result in
strong instability as temperatures continue to cool aloft. Expect
scattered thunderstorm development along the dryline during the afternoon/evening. However, more widespread storm development is
likely after 00Z as the low-level jet strengthens across West Texas.
Initial supercells will have a threat for all severe weather hazards
before eventual upscale growth into a MCS likely results in a
greater severe wind threat.

...Day 5/Tuesday - Central/East Texas into Louisiana...
Day 4 thunderstorms will likely be ongoing at the beginning of the
period along a frontal zone across central/East Texas and persist
eastward through the day. Destabilization remains questionable as
strong high pressure and the low-latitude nature of the mid-level
trough may limit northward movement of the warm front. The potential
for this front to be stationary, in addition to widespread
convection/cloud cover concerns along the front, preclude severe
weather probabilities at this time. However, there will likely be a
corridor along the frontal zone with some greater severe weather
threat which may become more clear as the event draws closer.

Additional severe storms will be possible Day 6 and 7 along the
frontal zone/composite outflow in Texas, but the location of this
feature and degree of destabilization along it will be highly
dependent on prior days convective activity. For these reasons, no probabilities have been added at this time.

..Bentley.. 05/02/2025

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ACUS48 KWNS 030858
SWOD48
SPC AC 030856

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0356 AM CDT Sat May 03 2025

Valid 061200Z - 111200Z

...DISCUSSION...
...D4/Tuesday...
The upper low in the Four Corners region will make more progress
eastward on Tuesday. It will be weakening with time, however. The
surface pattern in turn will be somewhat disorganized. At least some southeasterly winds at the surface will continue to advect richer
moisture into Central and East Texas. A warm front will be
positioned from the central Gulf coast northwestward to near the Red
River. A composite front/dryline is also expected in Central Texas.
The ECMWF is the most aggressive with early period precipitation and
has the farthest south cluster/MCS comparatively as well. Given the
forcing from an ejecting shortwave trough and stronger 850 mb flow
into the warm front, this solution appears to be more plausible at
this point. This would lead to considerable uncertainty as to the
degree of destabilization in parts of Central Texas into the Sabine
Valley. That said, wind fields will be supportive of severe storms.
Should more limited precipitation occur, severe storms could be more
focused along the warm front and dryline. Confidence in placement of
key features remains too low for highlights at this time.

...D5/Wednesday...
The upper-level low will become an open wave by Wednesday.
Significant loss of amplitude is also expected by this time. A belt
of stronger mid-level winds will remain over coastal Texas into the
central and parts of the eastern Gulf coast. With this upper-level
and surface pattern, it is not clear how far inland greater buoyancy
will reach. This uncertainty coupled with storm development not
being favorably timed diurnally reduces confidence in highlighting
any corridors of greater severe potential.

...D6/Thursday into the Weekend...
The elongated upper trough is forecast to become another weak cutoff
low in the lower Mississippi Valley. In the West, an upper-level
ridge will build and move over the Plains by the weekend. This
pattern does not suggest a significant risk of organized severe
storms, though mesoscale/conditional areas may eventually become
evident.

..Wendt.. 05/03/2025

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ACUS48 KWNS 040842
SWOD48
SPC AC 040841

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0341 AM CDT Sun May 04 2025

Valid 071200Z - 121200Z

...DISCUSSION...
The upper-level low in the Southwest will begin to weaken on
Wednesday. Thereafter, it will make slow eastward progress before
becoming a weak cutoff low over the lower Mississippi Valley by the
weekend. This upper-level pattern will help push a surface boundary
along and offshore of the Gulf Coast. As the weekend progresses,
this boundary will move further offshore along with the weak upper
low. In the West and Plains, upper-level ridging will become
prominent and remain in place into the following week.

Some moderate mid-level winds will likely remain along the Gulf
Coast at least until this coming weekend. With some lingering
moisture in the coastal regions, its possible that areas of
localized severe risk will develop. However, the overall pattern
will not be favorable for any areas of organized/predictable severe
risk.

..Wendt.. 05/04/2025

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ACUS48 KWNS 050831
SWOD48
SPC AC 050830

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0330 AM CDT Mon May 05 2025

Valid 081200Z - 131200Z

...DISCUSSION...
From Thursday into the weekend, the upper-level pattern will be
characterized by an elongated trough in the East and a building
ridge in the West. With this weakly blocking pattern, slow
progression of these features can be expected. With the trough in
the East, moisture will be present south of a surface boundary
across parts of the Southeast and eventually into the Florida
Peninsula. Though organized severe potential appears low with this
activity, enough remnant mid-level flow could promote localized
strong storms. By next week, models currently suggest some troughing
is possible in the West. With preceding days of offshore winds
across the western Gulf, moisture quality ahead of any potential
trough is likely to be low.

..Wendt.. 05/05/2025

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ACUS48 KWNS 060856
SWOD48
SPC AC 060855

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0355 AM CDT Tue May 06 2025

Valid 091200Z - 141200Z

...DISCUSSION...
Late this week, an elongated upper trough from the Southeast into
the Northeast will evolve into a cutoff low centered roughly on the
Gulf Coast with stronger cyclonic flow remaining in the Northeast.
An upper-level ridge will continue to build in the West and Plains
and shift eastward into early next week. With the weak upper low
near the Gulf, this will spur repeated days of convection across
part of the Southeast and Florida. It is possible low-end severe
potential will exist with some of this activity until low/mid-level
lapse rates become poor. However, substantive severe threats are not
expected.

With the ridge building over the cutoff low, it will be slow to move
eastward. Model guidance suggests that this feature will reach the
East Coast around the middle of next week. At the same time, a
strong upper trough is expected to move into the West. Moisture
return into the Plains will begin as the trough moves eastward. That
said, at least a few days worth of offshore flow in the western Gulf
will likely limit the initial quality of that moisture return. The
potential for severe weather with the incoming western trough
remains uncertain at this point in time.

..Wendt.. 05/06/2025

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ACUS48 KWNS 070814
SWOD48
SPC AC 070813

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0313 AM CDT Wed May 07 2025

Valid 101200Z - 151200Z

...DISCUSSION...
From this weekend through early next week, an upper-level low will
be situated in the lower Mississippi Valley into the northern Gulf.
This feature will drive repeated days of convection within parts of
the Southeast into the Florida Peninsula. Lower-end severe potential
may occur with this activity, but how organized/intense it will be
is not certain. The upper-level low will become more progressive and
lift northeastward by the middle of next week. Shortwave ridging
aloft will move through the Plains into the Southeast in advance of
a western trough. With the presence of the upper low over the Gulf
Coast region, there will be offshore flow in the western Gulf for a
few days before moisture returns northward again in response to the
mid-week trough.

The largest uncertainty with this system will be the moisture
quality. Secondly, models currently project the strongest forcing to
be within the central/northern Plains, farther away from the
moisture plume moving north. At least as currently forecast, strong southwesterly/westerly winds aloft should overspread the
southern/central Plains by late next week. This particular trend in
guidance is recent and confidence is accordingly low, but model
trends will continue to be monitored in the coming days.

..Wendt.. 05/07/2025

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ACUS48 KWNS 080858
SWOD48
SPC AC 080856

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0356 AM CDT Thu May 08 2025

Valid 111200Z - 161200Z

...DISCUSSION...
...Southeast into Mid-Atlantic...
By early next week, the cutoff upper low is forecast to become more
progressive and move northeastward. As this occurs, convection will
begin to overspread more of the Southeast into southern portions of
Florida and eventually the Mid-Atlantic. At this time, the potential
for several days of precipitation/cloud cover to impact surface
heating does not suggest a substantive severe threat will exist.
Furthermore, mid-level flow will weaken with time as the low lifts
northeast. Moderate mid-level winds will remain over Florida until
midweek. While Central/South Florida could see relatively higher
severe potential on Tuesday into Wednesday, models still show
limited destabilization on account of the uncertain surface heating
described earlier.

...Northern Rockies/Plains...
Strong upper-level winds will overspread the northern Rockies on
Sunday. Mid-level ascent should be sufficient for potentially
scattered storm development. Moisture still appears it may be
limited, but some threat for severe wind gusts may accompany storms
on Sunday in parts of southwest into central Montana. Uncertainty in
storm intensity precludes highlights, however. As the trough
continues to shift eastward, moisture return may be sufficient
enough to support some potential for severe storms mid to late next
week in parts of the Dakotas into Iowa/Minnesota. Aside from
questions about low-level moisture, timing and structure of the
trough varies in guidance and makes the coverage/intensity of storms
too uncertain for highlights.

...Central/southern Plains...
Model guidance continues to show the potential for a trough to
impact these regions by mid/late next week. Timing and position of
the stronger winds/greatest forcing continues to shift spatially,
however. Given that both the GEFS/EPS ensembles show a trough in the
mean next week does give some confidence in the general pattern.
Available ML guidance has also picked up on the pattern shift and
started to show an increased signal for severe potential. However,
significant uncertainties remain. With the cutoff nature of the
upper low in the lower Mississippi Valley, it is a feature that is
not predictable in terms of how fast it will depart. If guidance is
correct, it will move out right as the trough nears the Plains. This
leaves little time for a deep moist layer to develop and move
northward after a few days of offshore winds in the western Gulf.
Low-level moisture forecasts ahead of the trough do show mid/upper
60s F dewpoints. That said, the moisture profile in the vertical is
quite poor. It is not until next weekend that a signal for deeper
moisture is evident in model guidance. Lastly, shortwave ridging
will be in place ahead of the trough. Temperatures aloft do not
appear likely to appreciably cool given the current forecast
evolution of the trough and capping will be a concern. Trends in
guidance will continue to be monitored.

..Wendt.. 05/08/2025

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ACUS48 KWNS 090901
SWOD48
SPC AC 090859

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Fri May 09 2025

Valid 121200Z - 171200Z

...DISCUSSION...
Based on the latest medium-range guidance, it appears that
large-scale mid/upper troughing will continue digging inland of the
Pacific coast, before gradually turning eastward toward the Rockies
during the early portion of next week. While this probably will be
accompanied by the development of modestly deep surface troughing
across the Great Plains, appreciable low-level moisture return, in
the wake of a mid-level low/trough slowly accelerating northeast of
the lower Mississippi Valley, through parts of the Mid South and
Ohio Valley, remains uncertain.

Even into mid-week, when it appears that the troughing may begin to
emerge from the Intermountain West/Rockies, while the downstream
troughing only slowly progresses across the Mid Atlantic, moisture
return (and destabilization) to the vicinity of the stronger forcing
for ascent may remain a potential limiting factor to severe
thunderstorm development.

Toward next Thursday/Friday, there does appear consensus that
stronger destabilization may begin to become better coupled with
large-scale forcing for ascent across the upper Mississippi
Valley/Midwest into Ohio Valley, as the mid-level troughing
progresses northeastward and eastward, around the periphery of
mid/upper ridging building north-northeast of the lower Mississippi
Valley. This appears to include at least a conditional risk for
organized severe convection, including a few supercells. Although
lingering uncertainties preclude introducing 15 percent or greater
severe probabilities at this time, this may change in later outlooks
for this period.

..Kerr.. 05/09/2025

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ACUS48 KWNS 100902
SWOD48
SPC AC 100900

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CDT Sat May 10 2025

Valid 131200Z - 181200Z

...DISCUSSION...
Medium-range guidance indicates that a generally amplified, split
mid/upper flow will persist across the mid-latitude Pacific through
North America next week. It appears that this will include at least
a couple of significant troughs digging inland of the U.S. Pacific
Coast. The first may already be in the process of developing
eastward across the Intermountain West early in this period
(Tuesday), before progressing across the Rockies, Great Plains and
Mississippi Valley during the middle through latter portion of next
week. This may be followed by another significant trough digging
inland of the Pacific coast by early next weekend.

The lead trough will be relatively close on the heels of the
remnants of an initially broad quasi-stationary/cut-off low, which
may only slowly progress east of the Mississippi Valley through
Atlantic Seaboard during the early to middle portion of next week.
Low-level moisture return, in the wake of this perturbation and
ahead of the mid-level trough emerging from the West, may continue
to be impacted across at least parts of the Great Plains into mid
week. Thereafter, there appears a general consensus that there will
be a better coupling of large-scale forcing for ascent, aided by
surface cyclogenesis, with a notable increase in low-level moisture
and destabilization across the lower Missouri Valley into the Upper
Midwest and lower Ohio Valley by late next Thursday into Thursday
night. In the presence of strong shear, it appears that this
environment could become supportive of supercells and/or one or two
organizing severe storm clusters.

Machine learning output and other guidance suggests that potential
for strong to severe thunderstorms could persist and potentially
become more widespread across the Ohio Valley into Mid Atlantic, and
southern Great Plains, next Friday and Saturday. However,
uncertainties remain too large at this time to introduce greater
than 15 percent severe probabilities.

..Kerr.. 05/10/2025

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ACUS48 KWNS 110902
SWOD48
SPC AC 110900

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CDT Sun May 11 2025

Valid 141200Z - 191200Z

...DISCUSSION...
Latest medium-range output remains generally similar to prior runs
concerning the pattern evolution Wednesday into Thursday. A
significant short wave trough emerging from the Intermountain West
is forecast to support modest cyclogenesis across the central and
northern Great Plains through the mid/upper Mississippi Valley
vicinity. It appears that this probably will be accompanied by
increasing potential for strong to severe thunderstorm development,
with severe probabilities maximizing across parts of the Midwest
late Thursday into Thursday night, as the stronger large-scale
forcing for ascent becomes better coupled with substantive
boundary-layer moistening and destabilization. Aided by steep lower/mid-tropospheric lapse rates associated with elevated
mixed-layer air, and moderate to strong low-level and deep-layer
shear, it appears that the environment will become conducive to the
evolution of an upscale growing and organizing convective system.
But initial convection may include supercells posing a risk for
large hail and a couple of tornadoes, before damaging wind gusts
become the predominate severe hazard.

Based on the subsequent pattern evolution, it appears that this
convection could persist into, or re-intensify, Friday across parts
of the mid/upper Ohio Valley, with additional upscale growing
convection evolving along a stalling trailing cold front near the
southern edge of the stronger westerlies. Into next weekend,
renewed cyclogenesis appears possible along the trailing flank of
the front across the south central Great Plains, where additional
strong to severe thunderstorm development may focus along a
developing warm front, and a developing dryline southward through
the plains, as the warm sector destabilizes with increasing Gulf
moisture return.

However, by late Thursday into Friday, and beyond, these
developments remain much more unclear, as spread among and within
the various medium-range models begins to increase. Substantive
differences begin to develop concerning the progressiveness of the
lead trough, and a trailing short wave trough emerging from the
mid-latitude Pacific. The uncertain impacts of potentially multiple
evolving large convective clusters on succeeding days adds to low predictability.

..Kerr.. 05/11/2025

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ACUS48 KWNS 120901
SWOD48
SPC AC 120859

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Mon May 12 2025

Valid 151200Z - 201200Z

...DISCUSSION...
An active period of severe weather is anticipated through early next
week based on recent trends in long-range guidance. A transition to
a progressive upper-level regime is expected over the next seven
days as a series of upper waves traverse the CONUS with favorable
wavelengths for air mass/moisture recovery into central portions of
the CONUS. Although both the GFS and ECMWF (and their respective
ensemble families) show similar synoptic evolutions through the
extended period, predictability in any severe threat currently
appears greatest on D4/Thursday and D5/Friday.

...D4/Thursday...
The upper-level trough currently over the Pacific Northwest is
forecast to eject into the upper MS River Valley through the day
Thursday with an attendant surface low deepening across the upper MS
Valley. A Pacific front is forecast to push east into an expanding
warm sector that should span from the MS River into the upper Great
Lakes and OH River Valley. Strong mid-level flow orthogonal to the
front should generally promote discrete/semi-discrete convection by
late afternoon on the eastern fringe of a stout EML. The consistent
signal for QPF within the warm sector coincident with 50-60 knot
mid-level flow and the intensifying nature of the synoptic low
suggests that a widespread severe weather event is possible and may
expand further east than depicted in previous forecasts. Despite
these trends, regional discrepancies among guidance limit confidence
in where the more robust severe corridors will become established.
Notable factors limiting confidence are the potential for strong
capping across much of the OH Valley and a faster progression of the
surface low/front in recent GFS/GEFS solutions (which typically
exhibit a fast bias at this range).

...D5/Friday...
The Pacific front/outflow associated with D4/Thursday's convection
is expected to stall across the lower OH Valley/mid-MS Valley before
gradually returning north as an effective warm front on Friday.
Ensemble guidance shows a reasonably strong signal for dewpoints in
the mid/upper 60s (potentially into the low 70s) along and south of
this boundary by peak heating. A mid-level impulse propagating over
the region should maintain elongated hodographs and provide
sufficient lift for thunderstorm development along the boundary.
This synoptic regime suggests that one or more organized
clusters/linear segments may propagate along the boundary and into
parts of the mid-MS Valley, lower OH Valley, and potentially into
the TN Valley. Given the thermodynamic and kinematic environment
forecast by ensemble guidance, such a cluster/line will likely pose
a severe threat. A 15% risk area has been introduced where the QPF
signal associated with this regime has been most consistent over
recent model runs, but further forecast refinements are expected.

..Moore.. 05/12/2025

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ACUS48 KWNS 130859
SWOD48
SPC AC 130858

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CDT Tue May 13 2025

Valid 161200Z - 211200Z

...DISCUSSION...
An active period of severe weather is anticipated through early next
week as a pair of upper-level troughs traverse the U.S. and will be
favorably timed to allow moisture recovery into central/southern
portions of the CONUS. The upper trough currently over the Pacific
Northwest is forecast to migrate into the Great Lakes region by this
weekend. In the wake of this feature, a second long-wave trough will
begin to deepen across the West before migrating into the Plains by
early/mid next week with attendant chances for strong/severe
thunderstorms.

...D4/Friday...
A stalled boundary will likely be draped from the Ozarks into the OH
Valley at the beginning of the forecast period. A weak,
low-amplitude mid-level perturbation emanating out of the central
Plains will promote secondary surface low development across the
southern Plains that will maintain southerly low-level flow. As
such, some northward migration of the boundary as an effective warm
front appears probable. Thunderstorm development along the boundary
is anticipated by late afternoon, and 40-50 knot mid-level flow
oriented along the frontal zone should promote initially
discrete/semi-discrete cells with the potential for upscale growth
into one or more organized clusters. Some disagreement in exactly
where the corridor of highest severe threat will become established
persists and is associated with the coverage and intensity of
ongoing convection Friday morning. Recent GFS/GEFS runs hint that
more isolated convection early Friday will allow for more aggressive
northward advancement of the front, while ECMWF solutions hint at
slower northward progression of the boundary. The 15% risk area has
been expanded to best encompass the overlap between these two
dichotomous solutions.

...D6/Sunday to D8/Tuesday...
A deepening upper level trough over the western states will promote
several days of lee troughing/cyclogenesis across the southern to
central High Plains beginning this weekend. This will allow for more
seasonal moisture return into the Plains with most ensemble members
showing dewpoints climbing into the low to mid 60s by D6/Sunday
afternoon across TX, OK, and southern KS. Deterministic solutions
continue to vary regarding the exact timing and evolution of the
upper-level wave (and any embedded impulses), but the general
consensus is that severe thunderstorms will be possible as
upper-level disturbances overspread the Plains and promote eastward
mixing of the dryline into an increasingly buoyant warm sector.
Confidence on any particular day remains too limited for risk
probabilities, but the overall synoptic regime and convective QPF
signals in ensemble guidance suggest that the potential for multiple
rounds of severe thunderstorms is increasing for the
southern/central Plains beginning D6/Sunday through D8/Tuesday.

..Moore.. 05/13/2025

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ACUS48 KWNS 140855
SWOD48
SPC AC 140853

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0353 AM CDT Wed May 14 2025

Valid 171200Z - 221200Z

...DISCUSSION...
An active period of severe weather remains likely through the
weekend and into early next week for portions of the central CONUS.
A weakening upper trough is forecast to migrate across the Northeast
late this weekend as a second upper wave begins to amplify over the
western states. This upper regime will favor surface pressure falls
across the High Plains that will promote south/southeasterly return
flow into the southern/central Plains through early next week.
Severe thunderstorm chances will increase as preceding upper
disturbances and the primary upper wave eject into the Plains over
the warm sector. While severe weather chances are anticipated most
days through the extended period, confidence in more focused, synoptically-driven corridors is currently greatest on D5/Sunday and
D6/Monday across the southern Plains.

...D5/Sunday to D6/Monday...
Increasing southwesterly flow aloft over the southern/central
Rockies will promote lee cyclogenesis across the central High Plains
beginning D4/Saturday through D7/Monday. This will foster moisture
return into northern TX, OK, and southern KS as a warm front lifts
north. Long-range ensemble guidance suggests dewpoints ranging from
the mid 60s to low 70s are likely by Sunday afternoon across the
southern High Plains to the east of a sharpening dryline. Recent
GFS/GEFS solutions have come into better alignment with ECMWF/EPS
runs that depict a leading impulse within the subtropical jet
overspreading the southern High Plains late Sunday afternoon.
Enhanced westerly low- to mid-level flow coupled with ascent
associated with the upper feature should promote eastward mixing of
the dryline with attendant chances for thunderstorm development
within a buoyant and strongly sheared environment.

The ejection of the primary trough axis on D6/Monday should result
in more widespread 50+ knot mid-level flow overspreading much of
OK/KS. The eastward migration of the surface low and trailing
dryline through the day should provide adequate forcing for ascent
for thunderstorm development within a buoyant and strongly sheared
environment, which should promote an organized, and potentially more widespread, severe threat.

More specific mesoscale details for both days remain unclear at this
range, but the general alignment of global deterministic/ensemble
guidance regarding the overall synoptic regime and convective
environment, combined with a consistent QPF signal on both days,
suggests predictability is high enough to introduce risk
probabilities.

...D4/Saturday...
A residual cold front associated with a weakening surface low over
the northern CONUS is expected to be draped from the southern
Appalachians southwestward into the mid-MS Valley/Ozark Plateau
region. Sufficient buoyancy and strong zonal flow aloft will likely
support organized convection along the frontal zone. While some
severe threat is anticipated, mid-level ridging and lingering
convection at the start of the day limit confidence/predictability
in where the better mesoscale corridors for severe convection will
become established.

...D7/Tuesday...
Some severe threat is expected to persist into Tuesday as a surface
low and attendant trough/dryline migrate east towards the Midwest.
Ensemble guidance hints at strong/severe thunderstorm potential
across parts of AR, MO, and the lower OH Valley, but spread among
deterministic solutions and the potential for lingering convection
from D6/Monday limits confidence at this range.

..Moore.. 05/14/2025

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ACUS48 KWNS 150859
SWOD48
SPC AC 150858

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CDT Thu May 15 2025

Valid 181200Z - 231200Z

...DISCUSSION...
Medium-range guidance indicates that the persistent, prominent
mid/upper ridging across the mid-latitude and subtropical eastern
Pacific will become suppressed late this coming weekend into early
next week, before breaking down through the remainder of this
period. As it does, amplified downstream troughing is forecast to
emerge from the Intermountain West. Sunday, this may commence
gradually, with one significant lead short wave perturbation
pivoting north-northeast of the southern Rockies, accompanied by
cyclogenesis across eastern Colorado, as an upstream perturbation
continues to dig toward the Four Corners region. It appears that
this trailing perturbation will then pivot across the southern
Rockies through the central/southern Great Plains by late Monday,
perhaps accompanied by renewed cyclogenesis across the Texas
Panhandle into central Great Plains.

Both days, the dryline and warm front may provide focus for
organized severe convective development, including supercells, in
the presence of strong deep-layer shear and thermodynamic profiles characterized by steep lapse rates and sizable CAPE. It appears
that a substantive risk for strong to severe thunderstorms will
persist into at least Tuesday, within a broadening warm sector as
the cyclone and associated mid-level troughing shift a bit more
rapidly eastward across the middle Mississippi Valley.

Convective potential becomes more unclear Wednesday into Thursday as
the cyclone likely weakens and synoptic developments become more
uncertain across the East.

..Kerr.. 05/15/2025

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ACUS48 KWNS 160901
SWOD48
SPC AC 160900

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CDT Fri May 16 2025

Valid 191200Z - 241200Z

...DISCUSSION...
...D4/Monday - Central/Southern Plains into the Midwest...
A very moist and unstable environment will be present east of a
dryline across Kansas and Oklahoma on Monday morning. A surface low
across Kansas/Nebraska will weaken through the day and reconcentrate
farther south as a negatively tilted mid-level shortwave trough
moves into the central/southern Plains. The evolution of the upper
pattern will have some impact on the location and severity of the
severe weather threat on Monday. Despite these uncertainties, height
falls across a sharp dryline with a strongly unstable and uncapped
warm sector and supercell wind profiles should support severe storms
along and east of I-35 in Oklahoma and into southeast Kansas. All
severe weather hazards will be possible from any supercells which
mature on Monday.

Storms will be possible farther north across eastern Kansas and
western Missouri, but storm intensity is less clear given weaker
instability and messier storm mode along the warm frontal zone. In
addition, some elevated hail will be possible north of the warm
front into southeast Nebraska and Iowa.

...D5/Tuesday...
Thunderstorms will likely be ongoing at the beginning of the period
across the Midwest and perhaps as far south as eastern Oklahoma and
western Arkansas. These storms and their associated cloud cover will
have significant impact on destabilization across a broad warm
sector on Tuesday. A deepening mid-level low will develop across the
Plains and start to advance east on Tuesday. A strong mid-level jet
streak along the southern periphery of this upper low will
overspread the warm sector providing ample shear for storm
organization. Storm intensity remains uncertain on Tuesday due to
antecedent precipitation/cloud cover and differences in model
guidance. However, a broad region of strong to severe storms appears
possible from East Texas to northern Missouri and central Illinois
on Tuesday.

...Day 6-8...
A few strong to severe storms are possible on Day 6/Wednesday across
the Carolinas before the cold front moves offshore. Storm
coverage/intensity remains unclear at this time given the prior 2
days of storms and uncertainties in the upper-level pattern from
global guidance. Therefore, no probabilities are warranted at this
time. Beyond Day 6, severe weather concerns lessen as quality
moisture is mostly shunted offshore across the CONUS as a cold front
surges into the Gulf/Atlantic.

..Bentley.. 05/16/2025

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ACUS48 KWNS 170841
SWOD48
SPC AC 170840

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0340 AM CDT Sat May 17 2025

Valid 201200Z - 251200Z

...DISCUSSION...
...Day 4/Tuesday...
As the primary mid-level trough shifts east on Tuesday, scattered
severe thunderstorms are likely across parts of the Mid-Mississippi
Valley into the Tennessee Valley. Upper 60s to low 70s dewpoints
will be present ahead of a cold front. Convection/cloud cover from
Day 3 convection across the Plains/Ozarks will impact
destabilization across Kentucky and into the Ohio Valley. However,
farther south, strong destabilization is likely as the boundary
layer heats beneath steepening mid-level lapse rates. 50 to 60 knots
of mid-level flow will overspread this unstable warm sector during
the afternoon Tuesday. As this occurs, an uncapped boundary layer
and synoptic scale ascent should combine for scattered severe storm development. Wherever moderate to strong instability develops, most
likely south of the TN/KY border, supercells are anticipated with a
primary threat for large hail. By later in the evening, storms may
congeal into a MCS with an increasing damaging wind threat.

...Day 5/Wednesday...
A cold front will advance across the Appalachians on Tuesday
night/Wednesday morning. Moderate instability is forecast ahead of
this cold front Wednesday morning/early afternoon. A few strong to
severe storms may develop along the front before it moves into the
Atlantic. However, the limited duration of this threat, and
potential for timing shifts as newer guidance arrives, precludes
severe weather probabilities at this time.

...Day6-8..
A relatively benign severe weather pattern is expected from
Thursday/Day 6 into next weekend as a cold front pushes into the
Gulf. A few storms are possible along the cold front as it moves
south along the Florida Peninsula on Thursday. Otherwise, more
robust moisture recovery will begin Thursday night. Overall,
moisture quality will be low initially, but eventually some threat
may develop across the Plains as low-level moisture advection
continues.

..Bentley.. 05/17/2025

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ACUS48 KWNS 180846
SWOD48
SPC AC 180845

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0345 AM CDT Sun May 18 2025

Valid 211200Z - 261200Z

...DISCUSSION...
A few strong to isolated severe storms are possible in the eastern
Carolinas on Wednesday as a mid-level trough shifts east across the
eastern CONUS. It is unclear whether there will be substantial time
for destabilization before the surface low/front moves into the
Atlantic Ocean. Therefore, no probabilities are necessary for
Wednesday/D4 at this time.

Once this front moves offshore, a more benign period of severe
storms appears likely. The cold front will move south near the Gulf
Coast and into Florida with mostly sub 60s dewpoints across the
Eastern CONUS in its wake. Farther west the front is expected to
stall across Texas with low-level flow expected to advect moisture
westward to the High Plains on Thursday/D5.

Sufficient moisture should be in place by D7/Saturday across the
Plains. Therefore, some greater severe weather potential will likely
return by next weekend. However, uncertainty currently remains high
regarding the amplitude of the mid-level ridging and the location of
surface boundaries. Therefore, no probabilities have been introduced
at this time.

..Bentley.. 05/18/2025

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ACUS48 KWNS 190853
SWOD48
SPC AC 190852

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0352 AM CDT Mon May 19 2025

Valid 221200Z - 271200Z

...DISCUSSION...
A dry airmass will be in place across most of the eastern CONUS on
Thursday/D4 as a cold front moves into the western Atlantic and
stalls near the Gulf Coast. This will likely represent the minimum
threat during the extended severe weather period, with isolated
strong to severe storms across Texas likely the only threat area.

Starting Friday/D5, richer low-level moisture will advect over the
southern High Plains. However, this will also correspond to
shortwave ridging building across the Plains over the weekend
followed by zonal flow into early next week. This pattern may
support some localized threat each day, but more widespread,
predictable severe weather is unlikely at an extended range. As
these days draw closer, more confined regions of threat may become
more clear and allow for severe weather probabilities to be added.

..Bentley.. 05/19/2025

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ACUS48 KWNS 200856
SWOD48
SPC AC 200855

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0355 AM CDT Tue May 20 2025

Valid 231200Z - 281200Z

...DISCUSSION...
Strong to severe storms are possible across the southern Plains
D4/Friday to D6/Sunday. Beyond Day 6, anomalous troughing is
forecast to develop across the Northeast with strong high pressure
building into the Plains. This would result in a southward cold
frontal surge and a lull in severe weather chances early next week.

...Day 4/Friday to Day 6/Sunday...
Mid-level ridging will build across the Plains on D4/Friday and
D5/Saturday. Moderate to strong instability is forecast to develop
across Texas and Oklahoma as upper 60s to low 70s dewpoints advect
northward. A warm front will likely set up somewhere in the northern
Oklahoma to central Kansas vicinity as weak lee cyclogenesis occurs
near the TX/OK Panhandle. Nocturnal increases in the low-level jet
will likely result in convection north of this warm front each night
with sufficient shear and instability for some severe storms. Storm
development farther south along the dryline remains more
questionable due to the weak synoptic scale forcing. Severe weather probabilities will likely be needed eventually across portions of
the central/southern Plains, but details remain too nebulous for 15% probabilities at this time.

..Bentley.. 05/20/2025

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ACUS48 KWNS 210852
SWOD48
SPC AC 210850

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0350 AM CDT Wed May 21 2025

Valid 241200Z - 291200Z

...DISCUSSION...
Severe weather is possible across portions of the central Plains on
Saturday and Sunday as a mid-level trough emerges from the Rockies
into the Plains. Upper 60s to low 70s dewpoints will result in
strong to very strong instability south of a frontal zone. This
front will initially be stationary across Kansas on Saturday before
starting to advance south Saturday night and Sunday. Given the
instability ahead of this front, widespread storm development is
likely. However, the severity of this convection remains
questionable. The operational GFS is the most aggressive with severe
weather potential as it maintains troughing into the Plains with
southwesterly flow around 40 knots forecast across the frontal zone
which should provide ample shear for severe storms given the likely
instability that will be in place. However, this appears to be an
outlier with weaker, more zonal flow preferred by the ECMWF and the
ECS and GEFS. Due to this uncertainty regarding the mid-level
troughing and shear across the warm sector, severe weather
probabilities are not warranted at this time.

High pressure will build into much of the eastern CONUS on Day
6/Monday and persist for much of the week. This will shunt a frontal
zone and the better moisture closer to the Gulf coast, removed from
the stronger mid-level westerlies. Therefore, thunderstorms will be
likely along this frontal zone through the week, but organized
severe storms are not expected to be that widespread.

..Bentley.. 05/21/2025

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ACUS48 KWNS 220904
SWOD48
SPC AC 220903

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0403 AM CDT Thu May 22 2025

Valid 251200Z - 301200Z

...DISCUSSION...
Severe storms are possible across parts of the central/southern High
Plains on D4/Sunday as ridging shifts east and broad southwesterly
flow overspreads the southern High Plains. Moderate to strong
instability is forecast with modest height falls and forecast
soundings show an uncapped airmass. Scattered to widespread
thunderstorms are likely across much of the warm sector across
central Oklahoma and northwest Texas. Details of storm mode and
hazard type remain nebulous at this time. However, a focused zone of
the most likely threat area exists across northwest Texas and
southwest Oklahoma where 15% probabilities have been introduced.

Beyond Day 4, some isolated strong to severe storms will be possible
along a stalled front from the Southeast to Far West Texas.
Mid-level shortwave troughs embedded within mostly zonal flow along
this frontal zone may focus some severe weather, but significant
uncertainty exists regarding the timing and amplitude of any of
these shortwave troughs. A few damaging wind gusts will be possible
from this activity, but a more widespread threat is not anticipated.

..Bentley.. 05/22/2025

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ACUS48 KWNS 230901
SWOD48
SPC AC 230900

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CDT Fri May 23 2025

Valid 261200Z - 311200Z

...DISCUSSION...
...Monday/Day 4 to Wednesday/Day 6...
The medium-range models move a mid-level trough into the southern
and central Plains on Monday. Ahead of the trough, a moist airmass
is forecast from the southern Plains into the Gulf Coast states.
Scattered thunderstorms are expected across much of this airmass
Monday afternoon. The greatest convective coverage should be located
in parts of central and east Texas, where warm advection is forecast
to be maximized. Across the moist airmass, moderate instability will
likely be in place by midday. In addition, westerly flow associated
with the trough, should be strong enough for a severe threat. Large
hail and severe gusts will be possible as a cluster or line of
storms moves southeastward into central and east Texas during the
afternoon and evening.

On Tuesday, the moist airmass is forecast to remain in place from
the southern Plains eastward into the Gulf Coast states, with the
mid-level trough moving into the Ozarks. Model forecasts suggest
that numerous thunderstorms will develop ahead of the trough in
parts of the Southeast, with more isolated development occurring
across the southern Plains. Although a severe threat will be
possible across parts of this airmass, mesoscale processes will
determine the most favorable areas for severe. It appears that
instability will support isolated wind damage and hail, but
predictability appears low concerning the spatial distribution of
any isolated threat.

On Wednesday, the most unstable air is forecast from parts of
central and south Texas eastward into the lower Mississippi Valley.
Although large-scale ascent is forecast to be weak, thunderstorms
should develop in areas that warm up sufficiently along residual
outflow boundaries. An isolated severe threat should develop during
the mid to late afternoon, but predictability appears to be low.

...Thursday/Day 7 and Friday/Day 8...
On Thursday and Friday, westerly mid-level flow is forecast over the
southern U.S., where an unstable airmass is expected to remain in
place. As surface temperatures warm each day, isolated to scattered thunderstorm development should take place. Although instability and
shear will be favorable for severe storms in a few areas,
predictability remains low.

In addition, on Friday convection will be possible ahead of a cold
front across parts of the Atlantic Seaboard. Enough instability
should be in place during the day for an isolated severe threat.
However, the spatial distribution of any potential threat appears to
have low predictability.

..Broyles.. 05/23/2025

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ACUS48 KWNS 240853
SWOD48
SPC AC 240852

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0352 AM CDT Sat May 24 2025

Valid 271200Z - 011200Z

...DISCUSSION...
...Tuesday/Day 4 and Wednesday/Day 5...
A mid-level trough is forecast to move eastward from the southern
and central Plains into the Southeast on Tuesday and Wednesday. A
moist and unstable airmass is forecast to be in place on both days
from the Texas Hill Country eastward into the central Gulf Coast
states. During the day on Tuesday and Wednesday, deep-layer shear
across this airmass is forecast to be marginal for organized severe thunderstorms. However, an isolated severe threat will be possible
in areas that strongly destabilize. Steep low-level lapse rates
could support severe gusts with storm-scale line segments that form
from afternoon into the overnight period.

Further west into the southern and central High Plains, an axis of
moderate instability is forecast to develop Wednesday afternoon from
eastern New Mexico into southeastern Colorado. Thunderstorms that
move off the higher terrain could develop an isolated severe threat.

...Thursday/Day 6 to Saturday/Day 8...
A mid-level shortwave trough is forecast to move into the Ark-La-Tex
on Thursday. Scattered thunderstorm will be possible near and ahead
of the trough during the day from central and north Texas
southeastward into the lower Mississippi Valley. If a storm-scale
convective system can become organized, then a swath of wind damage
will be possible. However, predictability remains low concerning
this potential.

On Friday and Saturday, a strong cold front is forecast to move
southward through the Gulf Coast states and into the Gulf of
America. Behind the front, a relatively dry air mass over much of
the central and eastern U.S. is expected to limit severe
thunderstorm potential.

..Broyles.. 05/24/2025

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ACUS48 KWNS 250854
SWOD48
SPC AC 250853

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0353 AM CDT Sun May 25 2025

Valid 281200Z - 021200Z

...DISCUSSION...
...Wednesday/Day 4 and Thursday/Day 5...
A mid-level low is forecast to move eastward into the upper
Mississippi Valley on Wednesday, as a cold front advances
southeastward across the southern and eastern U.S. Thunderstorm
development is expected to take place along and near the front
during the day as surface temperatures warm. An isolated severe
threat will be possible Wednesday afternoon and evening, mainly
across parts of the Southeast and southern Plains, where some areas
could moderately destabilize. Mid-level flow is forecast to be
somewhat weak, should could marginalize the severe threat in most
areas.

On Thursday, the mid-level low is forecast to move eastward across
the Great Lakes, as the previously mentioned front moves slowly
southeastward. The tail end of the front is forecast to be in the
southern Plains, where scattered thunderstorms should develop
Thursday afternoon. Over the southern Plains, northwest mid-level
flow is forecast to create enough deep-layer shear for isolated
severe storms. However, predictability is too low to delineate any
areas with a potentially greater risk.

...Friday/Day 6 to Sunday/Day 8...
From Friday to Sunday, a mid-level trough in the lower Great Lakes
is forecast to move into the western Atlantic, as another trough
develops in its wake, over the eastern U.S. Behind this trough,
northwest mid-level flow will remain in place across much of the
central and eastern U.S. In response, a relatively dry airmass is
forecast remain in place across much of the central and eastern U.S.
For this reason, the potential for strong thunderstorm development
is expected to remain isolated in most areas over the weekend.

..Broyles.. 05/25/2025

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ACUS48 KWNS 260859
SWOD48
SPC AC 260858

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CDT Mon May 26 2025

Valid 291200Z - 031200Z

...DISCUSSION...
...Thursday/Day 4 to Saturday/Day 6...
A mid-level trough will move eastward into the eastern U.S. on
Thursday, as a front remains over the Gulf Coast states and southern
Plains. Thunderstorm development will be possible near and to the
south of the front Thursday afternoon, with the greatest convective
coverage expected over parts of east Texas and the lower Mississippi
Valley. An isolated severe threat will be possible during the day on
Thursday as surface heating takes place. Any severe threat should be concentrated in areas where low-level convergence becomes maximized
near the front. At this time, confidence concerning a more focused
severe threat area is low.

On Friday, the front is forecast to move southward across the
southern Plains and Gulf Coast states. Moderate instability is
forecast to the south of the front across parts of south-central and
southwest Texas, and across parts of Florida. Isolated to scattered thunderstorms may develop in these areas, with a marginal severe
threat possible.

On Saturday, northerly flow at mid-levels is forecast to develop
over the Great Plains. In response, some models suggest surface high
pressure will be dominant across the Great Plains. This would limit
severe potential. However, other model solutions suggest that some
low-level moisture could return northward into the southern Plains.
If this occurs, isolated to scattered thunderstorms that develop in
the afternoon could have a marginal severe threat. Predictability is
low concerning any specific scenario.

...Sunday/Day 7 and Monday/Day 8...
Northerly flow at mid-levels is forecast to remain over the Great
Plains on Sunday, as a trough moves east-southeastward across the
Gulf of America. At the surface, a large area of high pressure is
forecast over the central and eastern U.S. Although isolated to
scattered thunderstorms could form Sunday afternoon over parts of
the Great Plains and Mississippi Valley, any severe threat is
expected to be isolated. This same setup is forecast to continue
into Monday.

Further northwest into parts of the northern High Plains on Monday,
model forecasts suggest a trough could move through the northern
Rockies and approach the northern High Plains. An axis of moderate
instability is forecast to develop by afternoon across parts of
western South Dakota and eastern Montana, where a severe threat
would be possible. However, predictability at this range is low.

..Broyles.. 05/26/2025

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ACUS48 KWNS 270859
SWOD48
SPC AC 270858

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CDT Tue May 27 2025

Valid 301200Z - 041200Z

...DISCUSSION...
...Friday/Day 4 to Sunday/Day 6...
On Friday, a mid-level trough is forecast to move eastward from the
mid Mississippi Valley into the eastern U.S. At the surface, a moist
airmass is forecast to be located from the Gulf Coast states
northeastward into the Carolinas, where moderate instability should
be in place by afternoon. Ahead of the trough, large-scale ascent
should support scattered thunderstorm development, with the greatest
convective coverage expected from Georgia northeastward into the
Carolinas. Model forecasts suggest that moderate deep-layer shear
will exist ahead of the trough, which will contribute to a
possibility for severe storms from mid afternoon into the early
evening. Large hail and wind damage would be the primary threats.

On Saturday and Sunday, a cold front is forecast to move southward
across the Gulf of America, as northwesterly mid-level flow develops
over the central U.S. A shortwave trough is forecast to move
southeastward from the central Plains on Saturday into the lower
Mississippi Valley on Sunday. Scattered thunderstorms should develop
ahead of a shortwave trough each afternoon and evening. An isolated
severe threat will be possible. However, the combination of
instability and deep-layer shear is not expected to be sufficient
for a greater severe threat.

...Monday/Day 7 and Tuesday/ Day 8...
A pronounced mid-level ridge is forecast to develop on Monday across
the central U.S., with the ridge moving eastward into the Great
Lakes on Tuesday. In the wake of the ridge, strong to severe
thunderstorm development will be possible over parts of the northern
Plains Monday afternoon and evening. On Tuesday, model forecasts
suggest that scattered thunderstorm development could take place
ahead of the trough in the upper Mississippi Valley, with additional
storm development over the lower to mid Missouri Valley. Although a
severe threat may develop, predictability for early next week is low
at this time.

..Broyles.. 05/27/2025

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ACUS48 KWNS 280901
SWOD48
SPC AC 280900

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CDT Wed May 28 2025

Valid 311200Z - 051200Z

...DISCUSSION...
...Saturday/Day 4 and Sunday/Day 5...
From Saturday into Sunday, a mid-level shortwave trough is forecast
to move from the central Plains into the Southeast. Instability is
not forecast be particularly strong head of the trough. However,
large-scale ascent will support scattered thunderstorm development
on Saturday in parts of the central Plains and Ozarks, and on Sunday
from east Texas into the lower Mississippi Valley. Deep-layer shear
should be adequate for isolated severe thunderstorm development. The
threat is expected to be marginal.

...Monday/Day 6 to Wednesday/Day 8...
During the early week period, a mid-level ridge is forecast to move
across the central U.S., as a shortwave trough moves through the
Desert Southwest. Ahead of this feature, low-level moisture will
increase across the Great Plains, as low-level flow strengthens in
the wake of the ridge. Surface dewpoints are expected to increase
into the 60s F across much of the Great Plains, which should allow
for moderate to strong destabilization in some areas during the
afternoon. Although large-scale ascent will generally be weak across
most of the Great Plains, thunderstorm development will be possible
Monday afternoon over parts of the High Plains. An isolated severe
threat could develop late Monday afternoon into the evening along
the western edge of the stronger instability from eastern New
Mexico, northward into western South Dakota.

During the mid week, the shortwave trough is forecast to move across
the central U.S. on Tuesday and into the Great Lakes on Wednesday.
Thunderstorm development is expected across an unstable airmass,
which is forecast to be located in the Great Plains. Forecast
instability and deep-layer shear suggest a severe threat will be
possible in areas that have sufficient large-scale forcing, although
confidence is low concerning any potential scenario. If model runs
maintain consistency and show more agreement among solutions over
the next couple of runs, a 15 percent area may be needed in parts of
the Great Plains during the early to mid week.

..Broyles.. 05/28/2025

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ACUS48 KWNS 290812
SWOD48
SPC AC 290811

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0311 AM CDT Thu May 29 2025

Valid 011200Z - 061200Z

...DISCUSSION...
...Sunday/Day 4 and Monday/Day 5...
On Sunday and Monday, a mid-level ridge is forecast to move eastward
across the north-central U.S. A low-level jet is forecast to develop
in the High Plains on Sunday with this feature strengthening on
Monday, as a trough moves through the Rockies. In response,
low-level moisture will increase across the Great Plains, allowing
for moderate destabilization across much of the region during the
day. Scattered thunderstorm development is expected Monday from
parts of the southern and central High Plains, northeastward along a
cold front into the Dakotas. Although deep-layer shear is not
forecast to be particular strong, the models do suggest that strong
instability will be possible across parts of the Dakotas by late
Monday afternoon. This likely would support a large hail and
wind-damage threat.

...Tuesday/Day 6 to Thursday/Day 8...
On Tuesday, the shortwave mid-level trough is forecast to move
eastward into the southern and central High Plains. Scattered
thunderstorms are expected Tuesday afternoon from the mid Missouri
Valley southward into eastern Kansas and east-central Oklahoma. In
addition to moderate/strong instability, large-scale ascent and
moderate deep-layer shear should support a severe threat during the
afternoon and evening. Supercells would be possible, with isolated
large hail and wind damage. Tornadoes could also occur.

On Wednesday, the cold front is forecast to move southeastward into
the mid Mississippi Valley, and southward into the southern Plains.
Mid-level flow near the front will be southwesterly. Ahead of the
front, surface dewpoints should be from the 60s to the mid 70s F,
which will contribute to moderate instability by afternoon. Although
deep-layer shear is not expected to be that strong near the front,
the instability should be enough for isolated severe storms in areas
where strong surface heating occurs. Predictability is low
concerning where the greater severe threat will be.

On Thursday, the front is forecast to move into the Southeast.
Thunderstorm development will be possible by afternoon along and
ahead of the front, from the Texas Coastal Plain northeastward into
the Gulf Coast states. Although moderate instability should be in
place in some areas by afternoon, deep-layer shear is forecast to be
weak enough to keep any severe threat localized.

..Broyles.. 05/29/2025

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ACUS48 KWNS 300901
SWOD48
SPC AC 300859

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Fri May 30 2025

Valid 021200Z - 071200Z

...DISCUSSION...
As mentioned in WPC's Extended Forecast Discussion, an amplified
split-flow pattern across the CONUS renders below-average
predictability through the period. Will maintain inherited
severe-weather areas for D4-5, with mesoscale severe potential
evident in D6 and beyond but with poor synoptic predictability.

...D4/Monday...
A positive-tilt mid/upper trough should shift east as an embedded
shortwave impulse over the northern Rockies tracks near the
international border over the northern Great Plains. A northeast/southwest-oriented cold front should accelerate southward
into the central High Plains while a weak frontal wave temporarily
stalls the front over the Red River Valley of the North. There are
pronounced signals for afternoon to evening convection along the
front. Initially steep mid-level lapse rates will be supportive of
scattered severe potential. But it appears that stronger mid-level
flow may lag to the cool side of the front, which may limit a
greater threat.

...D5/Tuesday...
Complex severe potential is expected across the central states.
Low-amplitude shortwave impulses should be progressing across parts
of the northern Upper Midwest to the central High Plains on Tuesday
morning. Some guidance suggests extensive overnight convection may
be ongoing within a favorably diffluent upper-flow regime,
characterized by a coupled southern-stream left-exit and
northern-stream right-entrance regime. This renders substantial
uncertainty on where more robust boundary-layer destabilization
should occur. Warm mid-level temperatures in the southern stream
should yield modest mid-level lapse rates, which further lowers
confidence. Nevertheless, a broad and rich moist sector and adequate
deep-layer shear, along with widespread convection during the afternoon/evening, indicate scattered severe storms remain possible.

..Grams.. 05/30/2025

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ACUS48 KWNS 310856
SWOD48
SPC AC 310854

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0354 AM CDT Sat May 31 2025

Valid 031200Z - 081200Z

...DISCUSSION...
Somewhat greater confidence exists for a more south-southwest to north-northeast oriented swath of severe on D4/Tuesday. This appears
focused from the southern Great Plains to the Midwest from midday
into early evening. Overall pattern appears less amplified after D4,
with nebulous severe potential in the central to eastern states.

...D4/Tuesday...
A low-amplitude southern-stream shortwave impulse may phase with a northern-stream shortwave trough in the Upper Great Lakes vicinity
by late Tuesday. The accompanying surface wave over KS may similarly
track northeastward along a cold front through the Upper Midwest.
Rich low-level moisture will become more prevalent ahead of the
front and should spread into at least WI. Extensive convection may
be ongoing at 12Z within an increasingly favorable diffluent
upper-flow regime that is coupled with a broad low-level jet. Amid
relatively warm 500-mb temperatures within the southwest flow regime
attendant to the southern-stream impulse, mid-level lapse rates will
likely be weak in the warm-moist sector. Where appreciable
boundary-layer heating can occur ahead of morning convection,
scattered severe storms are possible.

...D5-8/Wednesday-Saturday...
Weak mid-level lapse rates will be pervasive, suggesting that robust
diurnal heating will largely drive daily bouts of seemingly
lower-probability severe. Guidance consensus suggests a more zonal
mid-level flow regime may evolve towards D7/Friday, which would aid
in the development/expansion of the elevated mixed layer and a
return of steep mid-level lapse rates across the High Plains.

..Grams.. 05/31/2025

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ACUS48 KWNS 010832
SWOD48
SPC AC 010830

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0330 AM CDT Sun Jun 01 2025

Valid 041200Z - 091200Z

...DISCUSSION...
Enhanced mid-level southwesterlies initially present over the
central Great Lakes early Wednesday should become confined to ON/QC
as a lower-amplitude shortwave trough dampens. Trailing to the south
of this, low-probability severe is apparent on Wednesday afternoon
in the eastern Midwest, and on Thursday afternoon over the Northeast along/ahead of a decaying cold front.

Another southern-stream shortwave impulse is progged to move east
from the Southwest mid-week. But initial surface ridging downstream
over the southern High Plains suggests the potential severe area
will be limited. Greater potential may await D6-7/Friday-Saturday,
as the ridging breaks down and zonal mid-level flow returns in the
wake of the aforementioned impulse. This will yield strengthening
and expansion of the EML east of the CO Plateau. ML guidance from
both the latest 00Z SPC/NSSL GEFS and yesterday's 00Z NCAR ECENS
highlight 15 percent probabilities on D6-7/Friday-Saturday across
the TX Panhandle into western KS/OK. Potential MCVs embedded within
this regime appear too minor at this time frame to reliably
delineate an area, but bear watching for shorter-term outlooks.

..Grams.. 06/01/2025

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ACUS48 KWNS 020841
SWOD48
SPC AC 020839

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0339 AM CDT Mon Jun 02 2025

Valid 051200Z - 101200Z

...DISCUSSION...
Latest guidance has trended towards a climatologically active
extended period for severe potential. It appears that 15 percent
severe areas will likely be delineated each day within a persistent
split-flow regime. Belts of enhanced mid-level westerlies should
accompany the train of low-amplitude southern-stream shortwave
impulses. Meanwhile, above-average agreement exists with the
amplification of a large-scale trough into the north-central states
towards the end of the period. This would suppress the southern
stream southward in the southern Great Plains to Deep South.

Reliably timing individual low-amplitude impulses/MCVs can be
difficult in this setup. But it appears that the initial impulse
ejecting across the southern Rockies around 12Z Thursday should
serve to focus severe potential from the TX Panhandle into southern
KS on D4. This feature may continue eastward towards the Mid-MS
Valley/eastern Midwest on D5/Friday. But with probable weak
mid-level lapse rates downstream and lack of run-to-run continuity
across guidance, will defer on a 15 percent area highlight.

..Grams.. 06/02/2025

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ACUS48 KWNS 030852
SWOD48
SPC AC 030851

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0351 AM CDT Tue Jun 03 2025

Valid 061200Z - 111200Z

...DISCUSSION...
An active severe-weather pattern for repeated MCS development is
anticipated through this weekend, with more nebulous potential early
next week.

Medium-range guidance has converged to above-average consistency
with the large-scale pattern through this weekend. Enhanced zonal
mid-level flow within the southern stream should overlie a
seasonably rich and unstable air mass across the southern Great
Plains to the Deep South. Initial signal for south-central High
Plains nocturnal MCS development spreading east-southeast onto the
lower plains is evident late D3 and this will probably repeat on
D4/Friday night and perhaps on D5/Saturday night. This should
subside as a northern-stream upper trough amplifies into the
north-central states.

Remnant MCVs should focus downstream diurnal thunderstorm
development each afternoon through at least D6/Sunday. Given the
buoyancy/shear parameter space, sufficient confidence exists for
highlighting a scattered severe-storm threat on D4-5. Damaging winds
appear to be the dominant hazard in this pattern. An additional area
on D6 is plausible in later outlooks somewhere in the Deep South and
Gulf Coast States. For D7-8, severe potential is nebulous, but may
be tied to the evolution of the north-central states trough.

..Grams.. 06/03/2025

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ACUS48 KWNS 030919
SWOD48
SPC AC 030918

Day 4-8 Convective Outlook CORR 1
NWS Storm Prediction Center Norman OK
0418 AM CDT Tue Jun 03 2025

Valid 061200Z - 111200Z

CORRECTED FOR MISSING LABEL ON DAY 6

...DISCUSSION...
An active severe-weather pattern for repeated MCS development is
anticipated through this weekend, with more nebulous potential early
next week.

Medium-range guidance has converged to above-average consistency
with the large-scale pattern through this weekend. Enhanced zonal
mid-level flow within the southern stream should overlie a
seasonably rich and unstable air mass across the southern Great
Plains to the Deep South. Initial signal for south-central High
Plains nocturnal MCS development spreading east-southeast onto the
lower plains is evident late D3 and this will probably repeat on
D4/Friday night and perhaps on D5/Saturday night. This should
subside as a northern-stream upper trough amplifies into the
north-central states.

Remnant MCVs should focus downstream diurnal thunderstorm
development each afternoon through at least D6/Sunday. Given the
buoyancy/shear parameter space, sufficient confidence exists for
highlighting a scattered severe-storm threat on D4-5. Damaging winds
appear to be the dominant hazard in this pattern. An additional area
on D6 is plausible in later outlooks somewhere in the Deep South and
Gulf Coast States. For D7-8, severe potential is nebulous, but may
be tied to the evolution of the north-central states trough.

..Grams.. 06/03/2025

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ACUS48 KWNS 040853
SWOD48
SPC AC 040851

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0351 AM CDT Wed Jun 04 2025

Valid 071200Z - 121200Z

...DISCUSSION...
Another active day characterized by an ongoing MCS and remnant
downstream MCVs is anticipated on D4/Saturday, with a broad belt of
mainly damaging wind potential evident. Seasonably strong mid-level
westerlies are expected to remain coincident with rich low-level
moisture. Ample buoyancy should diurnally develop south of
pre-existing outflows. This multi-day pattern finally breaks down
into D5/Sunday with amplification of a large-scale trough from the
southern Prairie Provinces into the Upper Midwest. Mesoscale-focused
severe potential may linger into at least D5/Sunday over the
southern High Plains to the TX/OK Red River Valley and from the
central Gulf to south Atlantic Coasts.

Otherwise, low-probability severe potential could begin in a portion
of the northern Great Plains on D4/Saturday, in association with the
amplifying trough. This should subsequently shift eastward and
likely broaden across the Great Lakes into the Northeast through
early next week. Overall instability appears modest until a
potential increase later when stronger flow fields overlap richer
low-level moisture. Daily severe probabilities appear to be sub-15
percent at this range, with a relative maximum in the
D6-7/Monday-Tuesday timeframe over the Northeast. Current timing of
this trough exiting New England by around D8/Wednesday suggests a
relative minimum across the CONUS then.

..Grams.. 06/04/2025

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ACUS48 KWNS 050858
SWOD48
SPC AC 050856

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0356 AM CDT Thu Jun 05 2025

Valid 081200Z - 131200Z

...DISCUSSION...
The active severe-weather pattern from the southern High Plains to
the Southeast should persist into D4/Sunday. A low-amplitude
mid-level trough is progged across the Southeast with a belt of
enhanced westerlies. The degree of ongoing convection on Sunday
morning lowers confidence on how broad a region of scattered
severe-storm potential exists in the Southeast. The best area for less-impactful morning convection appears to be across the South
Atlantic Coastal Plain and adjacent eastern Piedmont. Scattered
damaging winds should be the main hazard from afternoon storms in
this region.

With a brief respite in the wake of multiple MCSs on D1 to early D3,
buoyancy should become large to locally extreme across a portion of
the southern High Plains to OK/TX Red River Valley by Sunday
afternoon. Latest guidance is quite insistent on more widespread
convective development during the late afternoon into Sunday night,
along the persistent quasi-stationary front. Although
mid/upper-level winds may be weaker relative to prior days, an
increased west-northwesterly component along with the very unstable
airmass will support severe hail/wind, which could be significant.

Guidance has shown less predictability in the D5-6/Monday-Tuesday
time frame. This seems related to handling of downstream MCV
evolution from the probable Sunday night MCS over OK/TX, as well as
individual shortwave impulses embedded within the broad upper trough
over the Upper Midwest to Great Lakes. Expansive swaths of
low-probability severe are evident across the southern to eastern
states but predictability is too low for any 15 percent highlights.
By mid-week, guidance is still signaling a reduction in overall
severe potential with a synoptic pattern change to predominantly
weak shear coincident with areas of moderate to large buoyancy.

..Grams.. 06/05/2025

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ACUS48 KWNS 060853
SWOD48
SPC AC 060852

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0352 AM CDT Fri Jun 06 2025

Valid 091200Z - 141200Z

...DISCUSSION...
A large MCS may be ongoing across the Ark-La-Tex vicinity on
D4/Monday morning. This MCS and attendant flow enhancement with its
MCV may support scattered damaging wind potential into the afternoon
downstream across the Deep South. How extensive an organized wind
threat persists is quite nebulous, given background mid-level
westerlies being weaker across the Southeast compared to prior days.

Sub-15 percent severe potential remains apparent across the Upper OH
Valley to Lower Great Lakes on D4/Monday, shifting east into the Northeast/Mid-Atlantic States on D5/Tuesday. A belt of strong
mid-level southwesterlies ahead of broad Great Lakes trough should
overlap parts of a weak cold front arcing south from a primary
surface cyclone over northeast ON to James Bay. Substantial
instability ahead of the front appears uncertain with progged weak
mid-level lapse rates and muted boundary-layer heating where the
stronger flow resides.

During D6-8/Wednesday-Friday, guidance continues to signal a
reduction in severe potential, as predominantly weak deep-layer
shear overlaps areas of moderate to large buoyancy.

..Grams.. 06/06/2025

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ACUS48 KWNS 070842
SWOD48
SPC AC 070841

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0341 AM CDT Sat Jun 07 2025

Valid 101200Z - 151200Z

...DISCUSSION...
Sub-15 percent severe potential remains apparent over the Mid-Atlantic/Northeast States on D4/Tuesday before a cold front
moves offshore. Instability progs remain weak where at least
moderate deep-layer shear is anticipated. It seems plausible that
the northern extent of larger buoyancy will be suppressed south in
the wake of extensive convection through D3 across the Southeast.

On D5-6/Wednesday-Thursday, guidance has trended towards some
amplification of a minor southern-stream shortwave impulse as it
drifts across the southern Great Plains. This could foster mesoscale
corridors of modest shear overlapping plentiful buoyancy in the
south-central states.

Western Gulf moisture will spread north and encompass much of the
central states through next weekend. Various shortwave impulses over
the Northwest may support multiple bouts of mesoscale-driven severe
potential along the northern periphery of the expansive Great Plains
buoyancy plume.

..Grams.. 06/07/2025

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ACUS48 KWNS 080849
SWOD48
SPC AC 080847

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0347 AM CDT Sun Jun 08 2025

Valid 111200Z - 161200Z

...DISCUSSION...
Guidance trends remain supportive of a more active pattern across
the northern High Plains to the Upper Midwest. GEFS-based ML
guidance from SPC and NSSL are now highlighting multiple days with
mesoscale areas of 15 percent probabilities, mainly over the
northern High Plains. Western Gulf moisture will spread north and
encompass much of the central states through next weekend. Various
shortwave impulses ejecting into the Northwest may support multiple
bouts of mesoscale-driven severe potential downstream along the
northern periphery of the expansive Great Plains buoyancy plume. The
initial impulse that is expected to reach northern CA by 12Z
Wednesday has poor predictability with its downstream evolution into
the North-Central States.

Low-probability severe potential may persist for several days with a
minor southern-stream shortwave impulse drifting east from the
southern Great Plains. This could foster daily mesoscale corridors
with a severe threat, as modest shear overlaps plentiful buoyancy
initially over the South-Central States.

..Grams.. 06/08/2025

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ACUS48 KWNS 090849
SWOD48
SPC AC 090847

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0347 AM CDT Mon Jun 09 2025

Valid 121200Z - 171200Z

...DISCUSSION...
Guidance remains supportive of a more active pattern across the
northern High Plains to the Upper Midwest. GEFS-based ML guidance
from SPC and NSSL depict mesoscale areas of 15 percent
probabilities, centered on eastern MT to the Dakotas. While
predictability for a specific day remains too low, the signal exists
for increasing potential during the weekend to early next week.

The initial low-amplitude shortwave trough over WY/eastern MT at 12Z
Thursday is progged to dampen as it moves east into the Upper
Midwest. An area-of-interest is evident over western SD and the NE
Panhandle on D4/Thursday afternoon, but a favorable buoyancy/shear
combination is too spatially confined for a 15 percent highlight.

A broad swath of moderate to strong mid-level southwesterlies may
persist for multiple days across the Northwest, downstream of a
large-scale trough near the West Coast. At the same time, the
expansive buoyancy plume over the central states should increase
northwestward, building higher CAPE into the northern High Plains
this weekend. Still, poor predictability persists with the
spatiotemporal details of individual shortwave impulses that may
support daily severe threats on D6-8/Saturday-Monday.

..Grams.. 06/09/2025

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ACUS48 KWNS 100849
SWOD48
SPC AC 100848

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0348 AM CDT Tue Jun 10 2025

Valid 131200Z - 181200Z

...DISCUSSION...
Models are in good agreement with the overall pattern through about
Sunday/D6, depicting upper ridging over the northern Plains and
rising heights across the Northeast and general troughiness over the
Northwest. During that same period, the disturbance over the
southern Plains is forecast to lift toward the mid MS Valley with
weakening trend.

The greatest risk of severe storms will generally stretch from the
northern Rockies into the northern Plains, as weak but backed
low-level winds maintain a moist plume out of the central Plains and
into MT and the Dakotas.

On Friday/D4, scattered strong storms may occur over central MT,
beneath modest southwest winds aloft and with around 1000 J/kg
MUCAPE. Instability will build further in the Saturday/D5 to
Sunday/D6 time frame, with greater storm coverage expected. However,
winds aloft will be marginal. Still, developing west to northwest
flow aloft could eventually result in an MCS pattern with attendant
wind potential. Predictability is low at this time, but the northern
and central Plains region will be monitored over the next several
days for potential categorical risk outlines.

..Jewell.. 06/10/2025

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ACUS48 KWNS 110839
SWOD48
SPC AC 110838

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0338 AM CDT Wed Jun 11 2025

Valid 141200Z - 191200Z

...DISCUSSION...
For Saturday/D4 into Sunday/D5, moderate southwest flow aloft will
remain over the Pacific Northwest and toward the northern Rockies,
with a gradual flattening of the upper ridge over the northern
Plains. Then through Wednesday/D8, modest west/northwest flow aloft
is likely to persist over the High Plains. Models diverge greatly
after this time frame. However, this pattern will generally favor
daily thunderstorms along the length of the High Plains, from MT
into eastern NM during the afternoon, and persisting into parts of
the Great Plains during the evenings.

The primary driver of severe potential will be a large area of
moderate to strong instability with 2000-3000+ J/kg MUCAPE
developing daily. As storms move off the higher terrain, corridors
of wind damage may materialize. Predictability is low this far out,
but categorical risk upgrades appear likely as these periods get
closer in time. The primary risk appears to be damaging winds, but
sporadic large hail is possible with the late afternoon activity.

..Jewell.. 06/11/2025

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ACUS48 KWNS 120835
SWOD48
SPC AC 120833

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0333 AM CDT Thu Jun 12 2025

Valid 151200Z - 201200Z

...DISCUSSION...
During the Sunday/D4 to Monday/D5 period, an upper ridge is forecast
to remain over the Plains, with modest southwest flow aloft over the
West. Models suggest that around Tuesday/D6, the upper ridge will
break down over the central/northern Plains, although the amplitude
and track of the wave is in question. Ample low-level moisture will
be in place from the Plains to the East Coast, with mid to upper 60s
F as far north as southern parts of the Great Lakes.

As a result of this large area of moisture and instability, widely
scattered thunderstorms will be common each day. The northern Plains
appears to have the greatest change of organized severe storms
includes MCS/s, but predictability is clearly low at this time with
the uncertain wave. However, it appears that the Tuesday/D6 to
Wednesday/D7 time frame may yield a corridor of organized damaging
wind potential over parts of the northern and central plains to
Midwest, and these trends will continue to be monitored.

..Jewell.. 06/12/2025

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ACUS48 KWNS 130901
SWOD48
SPC AC 130859

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Fri Jun 13 2025

Valid 161200Z - 211200Z

...DISCUSSION...
...Monday/Day 4 to Wednesday/Day 6...
A mid-level ridge across the Great Plains is forecast to become less
amplified on Monday, as multiple shortwave troughs move through
westerly flow across the north-central states. A moist airmass is
forecast across much of the central and northern Plains, where
moderate to strong instability appears likely to develop by
afternoon. Along the northern edge of the stronger instability,
scattered convective initiation is expected. The instability,
combined with moderate deep-layer shear, should support a severe
threat. Large hail and severe wind gusts will be possible during the
afternoon and evening.

The mid-level ridge is forecast to move eastward into the Missouri
Valley on Tuesday, as a trough moves into the Rockies. At the
surface, a moist airmass is forecast from the central Plains into
the Missouri Valley, where moderate to strong instability appears
likely to develop by afternoon. Large-scale ascent ahead of the
approaching trough is forecast to move into the central Plains
Tuesday evening. As a result, a large area of thunderstorms is
forecast to develop from northern Kansas into much of Nebraska.
Model forecasts suggest that moderate deep-layer shear will be in
place, which would support a large hail and wind-damage threat.

The mid-level trough is forecast to move across the Great Plains on
Wednesday. A moist airmass is forecast to remain in place to the
east of the trough across the lower Missouri and Mississippi
Valleys. Ahead of the trough, moderate instability is forecast by
afternoon. Thunderstorm development is expected with this unstable
airmass from eastern Kansas northeastward into the mid to upper
Mississippi Valley. A severe threat will be possible. The greatest
potential for severe storms could be from northern Missouri into
southern Wisconsin, along and near the axis of a low-level jet.

...Thursday/Day 7 and Friday/Day 8...
From Thursday into Friday, the mid-level trough, and an associated
cold front, is forecast to move from the mid Mississippi Valley to
the Eastern Seaboard. A moist and unstable airmass should be in
place ahead of the trough. Thunderstorm development will be possible
along parts of the front, and across the warm sector. Although a
severe threat may develop as instability increases during the day,
the timing of the front remains questionable and predictability is
low.

..Broyles.. 06/13/2025

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ACUS48 KWNS 140900
SWOD48
SPC AC 140859

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Sat Jun 14 2025

Valid 171200Z - 221200Z

...DISCUSSION...
...Tuesday/Day 4 and Wednesday/Day 5...
A mid-level trough is forecast to move into the High Plains on
Tuesday, as a cold front moves southward into the central Plains.
Ahead of the front, a moist and unstable airmass is forecast by
afternoon from Kansas and southeastern Nebraska into northern
Missouri. As surface temperatures warm during the day, thunderstorm
development will likely take place along parts of the front.
Moderate deep-layer shear is forecast across much of the region,
suggesting that storms should become organized. Supercells and short
intense line segments will be possible, with large hail and wind
damage as the primary threats.

The mid-level trough is forecast to move eastward through the
central states on Wednesday, as a cold front advances southeastward
into the lower Missouri Valley and western Great Lakes. Ahead of the
front, an axis of moderate instability is forecast to be in place by
afternoon. Thunderstorm development will be likely along parts of
the front. Moderate deep-layer shear is forecast along and near much
of the instability axis, suggesting that a severe threat will again
be possible during the afternoon and evening.

...Thursday/Day 6 to Saturday/Day 8...
The mid-level trough is forecast to move eastward into the Northeast
on Thursday. Ahead of the trough and its associated cold front,
moderate instability is expected to develop by afternoon.
Thunderstorm development will be most likely from parts of southern
New England southwestward into the Mid-Atlantic. Deep-layer shear
should be sufficient for an isolated severe threat. However, there
is considerable uncertainty due to the issues of frontal timing and
instability magnitude.

From Friday into Saturday, a mid-level ridge is forecast to move
eastward from the northern Plains into the Great Lakes. Although a
moist and unstable airmass will likely be in place across the
north-central U.S., large scale ascent should be weak across most of
the region. For this reason, predictability is low concerning any
potential severe threat.

..Broyles.. 06/14/2025

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ACUS48 KWNS 150900
SWOD48
SPC AC 150859

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Sun Jun 15 2025

Valid 181200Z - 231200Z

...DISCUSSION...
...Wednesday/Day 4 and Thursday/Day 5...
A mid-level trough is forecast to move through the Upper Midwest on
Wednesday, as a cold front advances southeastward into the lower
Missouri and mid-Mississippi Valleys. Ahead of the front, moderate
instability is forecast to develop by afternoon. Thunderstorms
appear likely to form along parts of the front, with several
clusters or line segments moving eastward toward the instability
axis during the late afternoon and early evening. Moderate
deep-layer shear should support severe storms with large hail and
wind damage as the primary threats.

The mid-level trough is forecast to move into the lower Great Lakes
and upper Ohio Valley on Thursday, as the cold front advances into
the central Appalachians. As the airmass ahead of the front
destabilizes, scattered thunderstorms are expected to form along and
ahead of the front. The models suggest that moderate deep-layer
shear will be in place across much of the northeastern U.S., which
will likely support organized storms. Damaging winds gusts will be
the most likely severe threat.

...Friday/Day 6 to Sunday/Day 8...
A shortwave mid-level ridge is forecast to move into the upper
Mississippi Valley on Friday. The ridge is forecast to remain over
the region on Saturday as mid-level heights rise. Beneath the ridge,
a moist and unstable airmass will likely be in place from the lower
to mid Missouri Valley northeastward into the western Great Lakes.
Within this airmass, isolated thunderstorm development should take
place both Friday and Saturday afternoon. Instability and deep-layer
shear appear sufficient for a localized severe threat. However, the
presence of the ridge introduces uncertainty as to where the
greatest potential for convection will be. For this reason,
predictability is low.

On Sunday, a mid-level trough is forecast to develop over the
Rockies as a ridge moves into the Great Lakes region. Although a
moist and unstable airmass should be located over parts of the
northern and eastern U.S., large-scale ascent and mid-level flow is
forecast to be relatively weak in most areas. For this reason, any
severe potential is expected to remain isolated.

..Broyles.. 06/15/2025

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ACUS48 KWNS 160857
SWOD48
SPC AC 160855

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0355 AM CDT Mon Jun 16 2025

Valid 191200Z - 241200Z

...DISCUSSION...
...Thursday/Day 4 and Friday/Day 5...
A mid-level trough is forecast to move into the Northeast on
Thursday, as a cold front advances eastward into the central
Appalachians. Ahead of the front, a moist airmass will be in place.
Moderate instability is expected to develop ahead of the front
across the Carolinas and Mid-Atlantic. As surface temperatures warm
during the day, scattered convective initiation will likely take
place along and ahead of the front. Moderate deep-layer shear and
steep low-level lapse rates should support a severe threat during
the afternoon, with the primary threat being damaging wind gusts.

On Friday, a mid-level ridge is forecast to move eastward across the
northern Plains. Beneath the ridge, a moist airmass will likely be
in place, and moderate instability is expected to develop within
this airmass. Ahead of the ridge, thunderstorm development will be
possible in the upper Mississippi Valley during the afternoon.
Although a severe threat may develop in areas that become moderately
unstable, there is some uncertainty concerning convective coverage
due to the presence of the ridge.

...Saturday/Day 6 to Monday/Day 8...
Mid-level heights are forecast to rise on Saturday and Sunday across
the eastern half of the nation, as a large area of high pressure
dominates. In the western U.S. over the weekend, a mid-level trough
is forecast to move northeastward from the Intermountain West into
the northern High Plains. Ahead of the trough, strong to severe
thunderstorms will be possible Saturday afternoon and evening across
parts of eastern Montana. In spite of the potential, there is still
spatial uncertainty concerning the timing of the trough. The severe
threat is expected to shift northeastward into Canada on Sunday.

On Monday, southwest mid-level flow is forecast over much of the
north-central U.S. Isolated to scattered thunderstorms will be
possible over parts of the northern Plains and upper Mississippi
Valley. An isolated severe threat will again be possible, but there
is considerable uncertainty on any potential scenario.

..Broyles.. 06/16/2025

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ACUS48 KWNS 170903
SWOD48
SPC AC 170901

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0401 AM CDT Tue Jun 17 2025

Valid 201200Z - 251200Z

...DISCUSSION...
...D4/Friday...
A surface cyclone is forecast to deepen over the northern/central
High Plains on Friday, as a mid/upper-level trough shifts gradually
eastward across the western CONUS. Strong to extreme buoyancy will
develop by afternoon across parts of the central/northern Plains,
along/south of an effective warm front that will extend east of the
surface low. Much of the warm sector will likely remain capped, but
isolated storm development will be possible by late afternoon
near/north of the warm front, with increasing storm coverage during
the evening in response to a strengthening low-level jet. Supercells
will be possible initially, though the pattern suggests potential
for an MCS to develop and move eastward Friday night across the
upper Great Lakes vicinity.

Guidance continues to vary substantially regarding the most favored
corridor for an organized severe threat. For example, the GFS/GEFS
is farther north across ND/northern MN, while the ECMWF/ECENS is
farther south across central MN/northern WI. Severe probabilities
will eventually be needed for this scenario, but confidence is the
favored corridor is too low for a 15% area.

Strong to severe storms may also develop across the northern Rockies
and spread eastward across MT, in association with the approaching mid/upper-level trough. Probabilities will likely be needed for this
scenario in future outlooks, though confidence is too low for a 15%
area at this time.

...D5/Saturday...
A similar surface pattern is expected over the Great Plains and
upper Midwest on Saturday compared to D4/Friday. However, an
amplifying upper ridge may tend to suppress storm development
through much of the period. Some severe potential may again evolve
across MT along the northwest periphery of the ridge. There may also
be some potential for strong to severe storms along the northeast
periphery of the ridge into parts of the lower Great Lakes and New
England.

...D6/Sunday - D8/Tuesday...
An upper-level ridge will remain prominent through the weekend into
early next week across parts of the central/eastern CONUS. Strong to
severe storms and possible MCS development could continue to occur
along the periphery of the ridge, but predictability becomes quite
low at this range regarding the details of any organized threat.

..Dean.. 06/17/2025

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ACUS48 KWNS 180843
SWOD48
SPC AC 180842

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0342 AM CDT Wed Jun 18 2025

Valid 211200Z - 261200Z

...DISCUSSION...
...D4/Saturday...
An amplified upper-level pattern will continue into Saturday, with a
prominent ridge extending from the Southeast into the Midwest and
Ohio Valley, and a deep trough over much of the West. Large to
extreme buoyancy will again develop across parts of the
central/northern Plains and Upper Midwest, but the influence of the
ridge will tend to suppress storm development across the warm
sector.

While differing in the details, some extended-range guidance
suggests that an MCS (or at least its remnant MCV) that develops
late on D3/Friday will move across the far northern Great Lakes and
adjacent parts of Ontario on Saturday, and potentially into parts of
the lower Great Lakes by Saturday evening. Should such an evolution
occur, some severe threat could accompany this system, but
predictability for such a scenario at this range is inherently low.

Farther west, there is substantial spread in guidance regarding the
magnitude of low-level moisture and instability across parts of MT
and northern WY into western ND on Saturday. However, if stronger
flow associated with the western trough can impinge upon favorable
instability, then an organized severe threat could evolve during the
afternoon and evening.

...D5/Sunday...
The western trough is generally forecast to take on more of a
positive tilt and eventually deamplify on Sunday, as a substantial
shortwave and midlevel jet maximum eject across parts of the
northern High Plains. As this occurs, a cold front will move across
parts of the northern/central Plains. At this time, it appears the
organized severe threat may be limited by very warm temperatures
aloft and a tendency for stronger deep-layer flow to lag behind the
front.

Strong buoyancy may spread into parts of the Ohio Valley and
Northeast on Sunday. Some organized severe potential could develop
within the instability gradient along the periphery of the ridge,
though mesoscale details remain highly uncertain at this time.

...D6/Monday - D8/Wednesday...
Uncertainty increases into early next week regarding evolution of
the synoptic pattern, though guidance generally suggests that an
upper ridge will remain prominent across parts of the eastern CONUS,
while a weak upper trough will persist across parts of the West into
the northern and central Plains. While some severe potential could
evolve across parts of the Great Plains, Great Lakes, and Northeast
along the periphery of the ridge, details regarding favored days and
locations remain highly uncertain.

..Dean.. 06/18/2025

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ACUS48 KWNS 190847
SWOD48
SPC AC 190845

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0345 AM CDT Thu Jun 19 2025

Valid 221200Z - 271200Z

...DISCUSSION...
...D4/Sunday...
The upper-level trough over the West is forecast to take on more of
a positive tilt on Sunday, as an embedded shortwave and attendant
midlevel jet maximum move across the northern Rockies/High Plains.
As this occurs, a surface low is forecast to move from SD toward the
upper Great Lakes, as a trailing cold front moves through the
northern/central Plains. Guidance varies regarding frontal timing,
though generally agrees that stronger mid/upper-level flow will tend
to lag behind the front.

While details remain uncertain, strong to potentially severe storms
may develop near/north of the surface low across parts of the
Dakotas/MN, and also along the trailing cold front into the central
Plains.

...D5/Monday - D8/Thursday...
The upper ridge across the Southeast is expected to remain in place
through at least early next week, with some guidance suggesting
potential for deamplification by the middle of the week. Multiple
shortwaves may emerge from the persistent (though weakening) western
trough through at least Wednesday, resulting in some potential for
strong to severe storms along the periphery of the upper ridge from
the Plains into the upper Midwest and Great Lakes, and possibly
parts of the Northeast. However, predictability remains quite low
regarding the details of any organized severe threats during this
time frame.

..Dean.. 06/19/2025

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ACUS48 KWNS 200844
SWOD48
SPC AC 200842

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0342 AM CDT Fri Jun 20 2025

Valid 231200Z - 281200Z

...DISCUSSION...
...D4/Monday...
A mid/upper-level shortwave trough initially over the northern
Plains and upper Midwest is forecast to move into Ontario on Monday,
along the northern periphery of an amplified upper ridge over the
eastern CONUS. A cold front will move through parts of the Great
Lakes, Upper Midwest and central Plains. The strongest deep-layer
flow may tend to lag behind the front, but moderate to strong
instability could support strong to potentially severe storms along
the front during the afternoon and evening.

Farther east, strong instability is generally forecast to develop
across parts of the Mid Atlantic into New England. However, due to
the influence of the upper ridge, there is currently little signal
for diurnal storm development across this region on Monday.

...D5/Tuesday...
Extended-range guidance is in reasonably good agreement that a cold
front will move southward across the lower Great Lakes into New
England on Tuesday. Favorable low-level moisture and strong
instability could support severe-storm potential along the front
during the afternoon and evening. However, coverage of storms is
currently uncertain, due to the lingering influence of the upper
ridge, and a tendency for stronger large-scale ascent to be
displaced well north of the front.

The western upper trough is forecast to deamplify on Tuesday, with
most guidance suggesting that mid/upper-level flow will tend to
weaken downstream across the Great Plains and upper Midwest.
However, strong to locally severe storms could again be possible
near the front, which may begin to move northward across the central
Plains as a warm front through the day.

...D6/Wednesday - D8/Friday...
Predictability begins to wane by the middle of next week regarding
the evolution of synoptic features across the CONUS, though the same
general pattern of a weak upper trough in the West and an upper
ridge over the East may continue through at least Wednesday. In the
absence of any apparent strong forcing mechanisms, organized severe
potential (if any) may tend be focused near a convectively
influenced front across parts of the Plains into the Midwest and
Great Lakes.

..Dean.. 06/20/2025

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ACUS48 KWNS 210843
SWOD48
SPC AC 210842

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0342 AM CDT Sat Jun 21 2025

Valid 241200Z - 291200Z

...DISCUSSION...
...D4/Tuesday...
Aside from some modest deamplification, little change to the
large-scale pattern is expected on Tuesday. An upper trough will
remain over the western CONUS, while an upper ridge persists over
the East.

Scattered to numerous thunderstorms will again be possible along the
western and northern periphery of the upper ridge, from the
central/southern High Plains into the Upper Midwest. Deep-layer flow
will generally be modest, but some severe threat could evolve in the
vicinity of an outflow-influenced front, in the presence of
favorable low-level moisture and moderate to strong buoyancy.

Farther east, a cold front is forecast to move southward across
parts of northern New England. Guidance varies regarding the extent
to which stronger deep-layer flow and large-scale ascent lag behind
the front, but moderate to strong buoyancy could support at least an
isolated severe threat during the afternoon and evening.

...D5/Wednesday...
Continued modest weakening of both the western trough and eastern
ridge is generally forecast on Wednesday. Scattered to numerous
thunderstorms will again be possible from the High Plains into the
Midwest, Great Lakes, and Northeast, along the periphery of the
ridge. Deep-layer flow is expected to be relatively weak across most
areas, but mesoscale corridors of somewhat greater severe threat
could evolve within this pattern.

...D6/Thursday - D8/Saturday...
Predictability of the large-scale pattern begins to notably decrease
by the end of next week. In general, an upper ridge may persist over
the Southeast, while one or more mid/upper-level shortwave troughs
move across the northern CONUS. This pattern may eventually yield an
increasing threat for organized severe storms across the northern Rockies/Plains and Upper Midwest, but details are very uncertain at
this forecast range.

..Dean.. 06/21/2025

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ACUS48 KWNS 220834
SWOD48
SPC AC 220832

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0332 AM CDT Sun Jun 22 2025

Valid 251200Z - 301200Z

...DISCUSSION...
...D4/Wednesday...
Extended-range guidance generally indicates that the persistent
upper ridge across the eastern CONUS will begin to dampen on
Wednesday. Multiple low-amplitude midlevel shortwave troughs will
move along the periphery of the upper ridge from the
central/northern High Plains into the Great Lakes. Mid/upper-level
flow will generally be rather weak, but may be locally stronger in
the vicinity of any shortwave troughs.

Some severe threat could develop where pockets of somewhat stronger
flow overlap moderate to strong buoyancy along the periphery of the
ridge. An MCS may develop late on D3/Tuesday and move across parts
of the central Plains and Midwest into at least early Wednesday.
This MCS could persist through the day, with additional development
possible along an outflow-influenced front. Other strong to severe
storms may again develop across parts of the central/northern High
Plains. Confidence regarding the details of any organized severe
threat is too low to delineate a 15% area at this time.

...D5/Thursday - D8/Sunday...
Guidance generally suggests that the persistent upper ridge will
continue to weaken with time, resulting in a more zonal pattern by
the upcoming weekend. Stronger flow may become increasingly confined
to the northern tier of states. This could lead to periodic severe
threats across parts of the northern Plains into the Great Lakes and
Northeast.

One area of interest is across parts of the northern Plains Friday
into Saturday. Some guidance takes a mid/upper-level shortwave
trough from the Pacific Northwest into the northern Great Plains
during this period, where it may impinge upon increasing low-level
moisture and instability, resulting in potential for organized
severe storms.

..Dean.. 06/22/2025

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ACUS48 KWNS 230901
SWOD48
SPC AC 230859

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Mon Jun 23 2025

Valid 261200Z - 011200Z

...DISCUSSION...
...D4/Thursday: Parts of the Midwest/Great Lakes...
An area of interest for severe-storm potential on Thursday resides
from eastern IA/southeast MN into northern IL/southern WI. A
mid/upper-level shortwave trough is generally forecast to move
across parts of the Midwest into the Great Lakes during the
afternoon, potentially accompanied by a frontal wave. While
deep-layer flow will generally remain rather modest, rich low-level
moisture and strong heating will support moderate to strong buoyancy along/south of the front. Strong to potentially severe storms may
develop as the approaching shortwave trough impinges upon the
favorable buoyancy. Uncertainty regarding frontal position and the
sufficiency of deep-layer shear precludes higher confidence at this
time.

...D5/Friday: Northern Plains...
An area of interest for Friday resides across parts of the northern
Great Plains. A mid/upper-level shortwave trough is forecast to move
across the northern Rockies toward the northern High Plains, though considerable spread remains regarding the timing of this relatively low-amplitude shortwave and attendant cold front. The front may
impinge upon strong instability across parts of the Dakotas, with
scattered storm and eventual MCS development possible. Deep-layer
shear may remain relatively modest, but the magnitude of instability
will likely support some organized severe threat.

...D6/Saturday: Northern Plains/Upper Midwest...
Some continuation of severe-storm potential is possible into
Saturday, potentially shifting eastward into the Upper Midwest.
Spread in guidance becomes quite large at this range regarding
placement of the warm sector Saturday afternoon, but strong
instability and at least modest deep-layer shear could support
severe storms along/east of the cold front.

..Dean.. 06/23/2025

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ACUS48 KWNS 240858
SWOD48
SPC AC 240857

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0357 AM CDT Tue Jun 24 2025

Valid 271200Z - 021200Z

...DISCUSSION...
Models are in good agreement with the overall pattern through
Tuesday/D8, depicting a low-amplitude trough moving from the
northwestern states on Friday/D4 across the northern tier of states
and toward the Great Lakes by around Sunday/D6. This wave is then
forecast to amplify across Ontario/Quebec through the end of the
period, with cooler/more stable air pushing south with a cold front
from the Midwest into the Northeast.

Severe storms are currently forecast over parts of the Dakotas into
northwest MN on Friday/D4 as the stronger flow aloft interacts with
a moist and unstable air mass already in place. Damaging winds
appear the most likely mode of severe, along with sporadic large
hail as storms form during the afternoon within a surface trough,
and beneath increasing winds aloft. While severe storms may also
occur on Saturday/D5 over parts of the northern Plains or upper MS
Valley, predictability is lower given expected storms the previous
day and potential for long-lived convective systems. However, given
such strong instability forecast on Saturday/D5, a risk area is
likely to be issued in later outlook cycles over parts of the upper
Midwest/MS Valley.

Elsewhere, daily thunderstorms within the moist and unstable air
mass are forecast for the bulk of CONUS from the Plains eastward,
though in a generally weak shear environment. Portions of those
areas may see low/marginal probabilities as the events enter into
the Day 3 outlook time frame.

..Jewell.. 06/24/2025

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ACUS48 KWNS 250830
SWOD48
SPC AC 250829

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0329 AM CDT Wed Jun 25 2025

Valid 281200Z - 031200Z

...DISCUSSION...
Models are in general agreement with the upper air pattern, but
increasing spread is seen from Sunday/D5 and beyond.

On Saturday/D4, a low amplitude wave will lift out of the
ND/northern MN vicinity and move into Ontario. This will result in
temporary height rises during the day before gradual falls occur
overnight and into as a secondary wave moves from MT into the
Dakotas overnight. Early day storms may exist over parts of northern
MN in association with the low-level jet, and this activity could
weaken during the day. Then, strong instability is forecast for
several models, perhaps MUCAPE to around 5000 J/kg, over eastern SD
and NE and into IA and MN. Heating within the surface trough may
spur afternoon development from SD into NE, with some potential for
activity to spread east/northeast. However, shear will likely be
weak, with 500 mb winds averaging around 15 kt. Despite very strong instability, the weak-forcing situation in the wake of the exiting
wave suggests low-predictability at this time.

Around Sunday/D5, the secondary wave is forecast to amplify across
the upper MS Valley and upper Great Lakes, with a cold front pushing
south and extending roughly from WI to NE. Strong instability will
likely exist ahead of such a boundary, though shear will again be
weak. Still, storms will likely develop across the region, with
areas of damaging gusts potential.

From Monday/D6 through Wednesday/D8, the aforementioned trough will
spread across the Great Lakes and Northeast, with what appears to be
an end to the extreme instability levels. Scattered storms will
likely persist over much of the Southeast and Mid Atlantic, with
sporadic strong gusts daily.

..Jewell.. 06/25/2025

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ACUS48 KWNS 260854
SWOD48
SPC AC 260852

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0352 AM CDT Thu Jun 26 2025

Valid 291200Z - 041200Z

...DISCUSSION...
On the large scale, a low-amplitude upper trough over the northern
Plains on Sunday/D4 will amplify as it moves toward the upper Great
Lakes into Monday/D5, and more so into Tuesday/D6 when it will
stretch across into the Northeast.

At the surface, high pressure will extend into the northern to
central Plains on Sunday/D4, with a trough affecting the upper MS
Valley to central Plains. This trough/front will push farther south
on Monday/D5, extending roughly from the OH Valley into the southern
Plains, and eventually, into the Gulf Coast states into Wednesday/D7
as high pressure spreads into the MS Valley.

For the period, instability looks to be strongest on Sunday/D4 ahead
of the front from NE/KS into IA/MO/IL with upper 60s to lower 70s F
dewpoints common. While unstable, only weak westerly flow aloft will
be present, and this will likely result in south to southwest
propagating cluster of storms producing areas of gusty winds. Given
substantial storm coverage over much of the central Plains to
upper/middle MS Valley, predictability remains low for denoting
precise risk areas.

A low-end risk of severe storms with wind potential could develop
into the Mid Atlantic on Tuesday/D6 as the Great Lakes/Northeast
trough amplifies with westerlies increasing to 30 to perhaps 40 kt
at 500 mb. Otherwise, scattered storms will also occur away from
this boundary, across much of the Southeast as the moisture and
instability remain in place in a weak shear environment.

..Jewell.. 06/26/2025

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ACUS48 KWNS 270856
SWOD48
SPC AC 270855

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0355 AM CDT Fri Jun 27 2025

Valid 301200Z - 051200Z

...DISCUSSION...
A mid-level trough will amplify across the Great Lakes at the
beginning of the period D4/Monday and shift into the Northeast by
Tuesday. A surface cold front will shift east across the Great Lakes
on Monday and to the Northeast and Mid-Atlantic on Tuesday. Moderate instability may develop across a large area east of the Appalachians
on Day 5/Tuesday. The strongest shear is forecast from Pennsylvania
northward, beneath the strongest mid-level flow. However, the
greatest instability should remain mostly south of this better flow.
Therefore, a favorable corridor may develop for some strong to
severe storms near the Mid-Atlantic/Carolinas where instability and
modest shear overlap, but this remains too uncertain for severe
weather probabilities at this time.

Beyond Day 5, mid-level ridging will shift east across the central
CONUS. At the surface, high pressure will build across much of the
eastern CONUS. The combination of weak mid-level flow beneath the
mid-level ridge and surface high pressure should limit severe
weather potential for Day 6 and beyond. Strong instability is
forecast to return to the northern Plains, but given the lack of
mid-level flow, any storms will likely only be marginally severe at
best. Some stronger mid-level flow may return to the northern Plains
by next weekend as the ridge starts to break down, which may be the
next chance for more organized severe storms in the latter portion
of the extended period.

..Bentley.. 06/27/2025

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ACUS48 KWNS 280801
SWOD48
SPC AC 280800

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 AM CDT Sat Jun 28 2025

Valid 011200Z - 061200Z

...DISCUSSION...
A mid-level trough will move from the Great Lakes to the Northeast
on Day 4/Tuesday. At the surface, a cold front will move east
through the period. Moderate instability is expected along this
front and some severe weather may be possible from the Mid-Atlantic
to the Northeast. Slight risk (15%) probabilities may eventually be
needed within this zone, but there is potential for
cloudcover/thunderstorm activity from Monday evening to impact
destabilization. Therefore, confidence is not high enough for
probabilities at this time.

Beyond Day 4, a relative lull in severe weather potential is
expected. Multiple reinforcing mid-level troughs will amplify the
larger-scale trough across the eastern CONUS. As this occurs, the
surface cold front will move south, potentially to the Gulf Coast
and into the western Atlantic. This will eliminate the very moist
airmass which resulted in moderate to strong instability across much
of the eastern CONUS for the past few weeks.

The greater low-level moisture is expected to remain and perhaps
advect north across the central Plains beneath a large-scale ridge.
This could result in some thunderstorm activity, but shear is
expected to be very weak, and the building ridge aloft may suppress
convection on D5/Wednesday to D6/Thursday.

By next weekend, this ridge is expected to flatten with some
stronger mid-level flow moving across the northern Plains. The exact
evolution of the upper-pattern remains uncertain and therefore,
confidence is low, but severe weather chances may increase across
the northern Plains by next weekend.

..Bentley.. 06/28/2025

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ACUS48 KWNS 290820
SWOD48
SPC AC 290819

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0319 AM CDT Sun Jun 29 2025

Valid 021200Z - 071200Z

...DISCUSSION...
The cold front which may result in severe weather on Day 3/Tuesday
will move into the Atlantic and near the Gulf Coast across Florida.
A reinforcing mid-level trough will maintain northerly flow across
the eastern CONUS as an area of high pressure builds into the
region. A drier, more continental airmass across the eastern CONUS
will keep severe weather chances minimal.

Upper 60s to low 70s dewpoints will remain across the Plains,
beneath a strong upper-level ridge. By the time the ridge starts to
break down on Day 6/Friday some severe weather is possible as a
mid-level trough moves into the northern Plains. However, the ECMWF
shows less than 20 knots of flow across the Plains. Therefore, shear
will likely be limited. Thunderstorms will be likely along the cold
front as it traverses the central and eastern CONUS next weekend.
However, the lack of stronger mid-level flow casts doubt on storm
organization. Therefore, no severe weather probabilities have been
added at this time.

..Bentley.. 06/29/2025

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ACUS48 KWNS 300855
SWOD48
SPC AC 300853

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0353 AM CDT Mon Jun 30 2025

Valid 031200Z - 081200Z

...DISCUSSION...
A mid-level ridge will start the extended period across the Plains
on D4/Thursday. This ridge will shift east through the extended
period. A surface low will develop in the lee of the Rockies and
move slowly north and east, reaching eastern Ontario by D7/Sunday.
This surface low and its associated cold front will likely be the
only potential for any severe weather during the extended period.
However, at this time it appears the stronger shear will be well
displaced from the greater instability. Therefore, severe weather
probabilities are not necessary at this time.

Outside of this frontal zone during the Day 4 to Day 7 period,
thunderstorms are likely. However, weak lapse rates and very weak
shear is anticipated, with minimal storm organization.

..Bentley.. 06/30/2025

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ACUS48 KWNS 010902
SWOD48
SPC AC 010900

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CDT Tue Jul 01 2025

Valid 041200Z - 091200Z

...DISCUSSION...
A mid-level trough will traverse the Northern Plains and Upper
Midwest on Friday. This will likely be the most substantial severe
weather threat during the extended period before broad, strong
ridging builds across much of the eastern/central CONUS.

...Day 4/Friday...
As a positively tilted mid-level trough traverses the northern
Plains on Friday, strong southerly flow will advect moisture
northward across a broad warm sector near the Upper Midwest. This
will result in moderate to strong instability as temperatures warm
well into the 80s. Widespread thunderstorms are likely along the
frontal zone during the afternoon/evening. 35 to 40 knots of
mid-level flow will overspread the warm sector which will provide
some shear for storm organization. However, southwesterly surface
winds will also increase during the afternoon within the warm front
and therefore, the net shear may remain somewhat minimal. Some
organized storms with a threat for large hail and severe wind gusts
are possible, but the aforementioned concerns about deep-layer shear
preclude the confidence needed for 15% severe weather probabilities
at this time.

Beyond Day 4, moderate to strong instability is forecast across much
of the central and eastern CONUS with widespread thunderstorm
activity likely. However, shear will remain mostly nebulous with the
stronger mid-level flow confined to areas north of the better
instability. Therefore, some marginal regional severe weather threat
will be likely most days, but a more organized severe weather risk
appears unlikely at this time.

..Bentley.. 07/01/2025

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ACUS48 KWNS 020859
SWOD48
SPC AC 020857

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0357 AM CDT Wed Jul 02 2025

Valid 051200Z - 101200Z

...DISCUSSION...
Some severe weather is possible on Day 5/Sunday and Day6/Monday
across portions of northern Montana and North Dakota as moderate
instability builds into the area with moderate mid-level flow
southeast of a trough across western Canada. The evolution and
timing of this trough remains uncertain and therefore, no severe
weather probabilities will be added at this time.

Beyond this timeframe, moderate to strong instability is forecast
across much of the central and eastern CONUS for much of the
extended forecast period with widespread thunderstorm activity
likely. Despite this storm coverage and instability, organized
severe weather seems unlikely given mostly weak deep-layer
shear/flow.

..Bentley.. 07/02/2025

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ACUS48 KWNS 030859
SWOD48
SPC AC 030858

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CDT Thu Jul 03 2025

Valid 061200Z - 111200Z

...DISCUSSION...
During the extended forecast period, a mid-level ridge will build
across the InterMountain West. Aside from the primary ridge, there
will be several mid-level shortwave troughs throughout the flow
across the Northwest and also from the Great Lakes to the Atlantic
coast. Widespread thunderstorm activity is expected throughout the
period, but stronger mid-level flow/shear should mostly stay north
of the stronger instability early in the period.

At some point next week (mid week according to the GFS and late next
week into the weekend ECMWF) mid-level northwesterly flow will
likely strengthen across the Plains (to the east of the primary
ridge). Whenever this occurs, the pattern would favor severe MCSs
given the forecast strong instability and moderate deep-layer shear.
However, the uncertainty in the upper-level pattern remains too
great to provide an accurate forecast of the timing and location of
the greatest severe weather threat toward the middle to late part of
next week.

..Bentley.. 07/03/2025

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ACUS48 KWNS 040842
SWOD48
SPC AC 040841

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0341 AM CDT Fri Jul 04 2025

Valid 071200Z - 121200Z

...DISCUSSION...
An upper ridge will gradually build over the Southwest while mainly
zonal mid-level flow persists over the northern CONUS through next
week. A relatively nebulous surface pattern will be the norm through
the extended range. Rich low-level moisture will overspread the
CONUS east of the Rockies Days 4-8/next Monday-Friday, supporting
scattered thunderstorm development over much of the Great Plains
into the MS Valley, and the Southeast into the Northeast. The best
chance for at least isolated strong to potentially severe storms in
the upcoming week would be across the north-central CONUS. Here, the
low-level moisture will advect northward beneath relatively cooler
temperatures and modest northwesterly flow/shear aloft. However,
given the nebulous and weakly forced environment, confidence is too
low to delineate severe probabilities over the north-central U.S.
for any given day.

..Squitieri.. 07/04/2025

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ACUS48 KWNS 050848
SWOD48
SPC AC 050846

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0346 AM CDT Sat Jul 05 2025

Valid 081200Z - 131200Z

...DISCUSSION...
An upper ridge will build across the Southwest and remain in place
this upcoming week into next weekend. Relatively zonal mid-level
flow will persist over the northern CONUS through the extended
forecast period, with multiple embedded impulses expected to track
eastward within the zonal flow. As the mid-level impulses traverse
the northern Plains, isolated strong to severe storm development
will be possible given the presence of ample buoyancy. However,
there are appreciable differences in the placement and timing of
these impulses among medium-range guidance members. Therefore,
severe probabilities have been withheld since confidence is
currently low regarding where and when organized clusters of severe
storms will develop.

..Squitieri.. 07/05/2025

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ACUS48 KWNS 060830
SWOD48
SPC AC 060829

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0329 AM CDT Sun Jul 06 2025

Valid 091200Z - 141200Z

...DISCUSSION...
An upper ridge will remain in place across the Southwest while zonal
mid-level flow continues to support embedded impulses traversing the
northern CONUS this week into next weekend. The first notable
mid-level impulse, which will bring severe potential to the central
U.S. in the Days 2-3 time-frame, will approach the East Coast while
slowing its forward advance. The impulse should reach the East Coast
by Day 4 (Wednesday), providing adequate lift for at least scattered thunderstorms through the remainder of the week. Given preceding
rich low-level moisture, ample buoyancy will be available to support
at least isolated strong storms with potentially damaging gusts.

A more pronounced mid-level trough will approach the Northern Plains
in the Days 4-5 (Wednesday-Thursday) period, resulting in strong
surface troughing and the northward advection of rich low-level
moisture. Medium range guidance consensus shows that strong
instability will precede the upper/surface troughs, favoring the
development of severe storms. The first chance for severe storms
will be over the western Dakotas on Wednesday as the upper trough
approaches from the Northern Rockies. Upper support in this region
does not currently appear robust, so severe storms may occur on a
more isolated basis (hence no severe probabilities introduced at
this time). However, there is medium range guidance agreement in the
upper trough ejecting into the northern Plains on Day 5 (Thursday),
with some guidance suggesting that instability could become extreme.
Though it is difficult to confidently pinpoint storm mode this far
in advance, guidance hints at the development of a persistent,
elongated convective system, which may be capable of supporting all
severe hazards, especially severe winds. Severe probabilities have
been added to address this scenario.

As the pronounced mid-level trough progresses eastward, more
organized severe storms are possible over the MS Valley and perhaps
points east Day 6 onward. However, the intensity, coverage, and
location of severe potential will be highly dependent on the
evolution of convection from previous days, which is hard to know
this far in advance. Therefore, severe probabilities have been
withheld this outlook.

..Squitieri.. 07/06/2025

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ACUS48 KWNS 070844
SWOD48
SPC AC 070842

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0342 AM CDT Mon Jul 07 2025

Valid 101200Z - 151200Z

...DISCUSSION...
The Southwest upper ridge will gradually flatten as a more
progressive mid-level flow regime becomes established over the
northern CONUS later this week into early next week. Multiple
pronounced mid-level troughs, with cooler temperatures aloft, will
traverse the north-central U.S. and overspread rich low-level
moisture. Strong buoyancy will precede these troughs, and upon
lifting of this unstable airmass, at least scattered organized
thunderstorm development should ensue, with multiple rounds of
strong to severe storms possible.

...Day 4 (Thursday) - Northern Plains...
The first in a series of mid-level troughs will eject into the
northern Plains on Day 4/Thursday, encouraging surface lee troughing
across the central and northern Plains. Dewpoints into the 70s F,
beneath 8+ C/km mid-level lapse rates, will support strong to
locally extreme instability by afternoon peak heating. The ejection
of the upper trough will provide enough upper support for scattered thunderstorm development. Increasing westerly flow with height will
result in straight, elongated hodographs. Supercells should be the
main mode of convection, at least initially, with severe wind and
hail the primary threats.

...Days 5-6 (Friday-Saturday) - Midwest toward the Great Lakes...
The main mid-level trough will continue to slowly approach the Upper
MS Valley as a preceding mid-level impulse continues to advance
eastward. Potential exists for renewed thunderstorm development for
portions of the Upper MS Valley and Midwest on Friday, spreading
east with upper trough advancement toward the Great Lakes on
Saturday. Rich low-level moisture beneath steep mid-level lapse
rates will promote strong instability in the warm sector, amid
modest vertical wind shear. Somewhere in this region, strong to
severe storms are likely, with severe wind/hail the main concerns on
both Friday and Saturday. The timing and location of thunderstorm
initiation will be highly dependent on the position of remnant
outflow boundaries from storms during previous days. Such details
are quite challenging to point out this far in advance, precluding
severe probabilities at this time, though probabilities will likely
be needed in future outlooks.

...Days 7-8 (Sunday-Monday) - Upper Mississippi Valley...
The next in a series of mid-level troughs will traverse the
north-central CONUS toward the end of the period. Medium-range
guidance consensus depicts extreme instability (i.e. well over 4000
J/kg MLCAPE) preceding this trough, along with strong enough
westerly mid-level flow and accompanying vertical wind shear. As
such, another episode of organized severe storms is possible in the Sunday/Monday time-frame. However, given the seasonal weak forcing
associated with this second low-amplitude trough, run-to-run
guidance consistency is desired before severe probabilities are
delineated.

..Squitieri.. 07/07/2025

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ACUS48 KWNS 080818
SWOD48
SPC AC 080817

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0317 AM CDT Tue Jul 08 2025

Valid 111200Z - 161200Z

...DISCUSSION...
The overall current large-scale pattern will persist through this
forecast period, albeit with minor day-to-day variations. More
specifically, a mid-level ridge will persist across the western US,
although its center will meander from the Southwest US to off the
coast of California and back; a series of shortwave troughs of
varying intensity will quickly move across the northern Plains; and
a very warm, moist environment will remain entrenched across the
eastern US.

This overall pattern suggests episodic bouts of severe thunderstorms
on any given day. However, the timing and location of specific
episodes will be tied to mesoscale details and impacts from prior
days' convection which have low predictability on time scales of
this forecast period. As such, low confidence in the details of
required to identify any of these severe events currently precludes
any probabilistic delineation at this time.

That said, there are a couple of scenarios being monitored for
potential future highlights. The first is the potential for severe
storms across the southern Plains on Saturday or Sunday associated
with a residual boundary/front. However, impacts from a potential
overnight mesoscale convective system moving from the High Plains
into the Southern Plains on Friday night into Saturday lead to
little confidence in the placement of any boundaries and the
resulting severe potential.

Another potential is for severe convection across northern Minnesota
and the Upper Great Lakes early next week associated with a stronger
shortwave trough moving through southern Canada. However, guidance
continues to show high variance regarding the strength of moisture
return, degree of instability, and timing of the shortwave itself to
preclude unconditional severe probabilities at this time.

..Marsh.. 07/08/2025

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ACUS48 KWNS 090820
SWOD48
SPC AC 090818

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0318 AM CDT Wed Jul 09 2025

Valid 121200Z - 171200Z

...DISCUSSION...
The overall large-scale pattern looks to remain characterized by mid-to-upper-level ridging across the western United States with a
zonal to broadly cyclonic flow across the northern tier of the US
through the forecast period. At the same time, rich/moist low-level
moisture looks to remain entrenched across much of the eastern US,
sustained in part by broad, southerly flow, albeit with some
fluctuations in raw values. Global models continue to be bullish on
a seasonably strong cold front pushing south through much of the
central US late in the forecast period, ushering in a cooler/drier
airmass.

Strong-to-locally severe thunderstorms will be possible somewhere
across the eastern CONUS every day of the forecast period. However,
with synoptic-scale forcing/dynamics primarily constrained to
Canada, most thunderstorms will be determined by
sub-synoptic/mesoscale details dictated by/reinforced with each
prior day's convection. Thus, confidence is too low in any one
location on any given day to introduce unconditional severe
probabilities at this time.

However, some areas/scenarios of interest to monitor include the
southern Great Plains on Days 4-5/Saturday-Sunday as a moist, weakly
capped environment will exist in proximity to an increasing diffuse
surface boundary. Other areas include the East Coast most afternoons
and the along and ahead of seasonably strong cold front pushing
south through the Great Plains from Days 6-8.

For each of the areas of interest/scenarios of interest above, weak effective-layer shear stemming from generally weak tropospheric flow
will be a limiting factor for a more organized severe potential and
confidence to introduce unconditional probabilities.

..Marsh.. 07/09/2025

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ACUS48 KWNS 100818
SWOD48
SPC AC 100816

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0316 AM CDT Thu Jul 10 2025

Valid 131200Z - 181200Z

...DISCUSSION...
At the start of the forecast period, the mid-level pattern will
generally be zonal across much country, with the greatest height
gradient found across the northern United States. By the middle of
next week, a short-wave trough moving within the broader flow regime
will amplify the height field across the northern Rockies before
moving into the central US. The overall pattern recognition would
suggest the potential for at least isolated severe thunderstorms
ahead of this feature across then northern Plains into the Upper
Great Lakes. However, model run-to-run timing differences along with inter-model timing differences precludes the ability to identify 15% unconditional probabilities on any given day.

Associated with the aforementioned mid-level trough, a surface-cold
front will push south through much of the Plains and into the East.
Additional thunderstorms will be likely along the front, however,
the location of the front on any given day will be strongly
influenced by previous days' convection. As such, when coupled with
the uncertainty in the timing of any mid-level wave, predictability
is too low to identify unconditional probabilities at this time.

..Marsh.. 07/10/2025

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ACUS48 KWNS 110841
SWOD48
SPC AC 110840

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0340 AM CDT Fri Jul 11 2025

Valid 141200Z - 191200Z

...DISCUSSION...
A surface cold front across the southern Great Plains early in the
period will quickly redevelop northward into the northern Plains in
response to strong lee cyclogenesis across the northern High Plains.
This cyclogenesis will occur in response to a positive-tilt
short-wave trough moving through the broadly zonal mid-level flow
across the northern US.

This front will move back south during the period as a seasonably
strong high pressure builds southward into the central US in the
wake of the aforementioned short-wave trough. Thunderstorms are
likely to develop in the vicinity of the front/aggregate outflow
boundary each afternoon as it moves south. However, given the lack
of significant flow amplification as the mid-level wave crosses the
northern US, it is likely that thunderstorms will remain displaced
south of the requisite effective-layer shear needed to promote an
organized severe threat identifiable at this time range.

One exception to the idea that storms will be displaced from the
better shear may take place on Monday/Day-4 across portions of North
Dakota. Here, low-level moisture will surge northward in response to
the aforementioned northern High Plains lee cyclogenesis. Steep
mid-level lapse rates will overspread the northern Great Plains
during the day, yielding most-unstable CAPE values ranging from 1000
J/kg to perhaps 3000 J/kg depending on model guidance.

However, run-to-run inconsistency in the space and time evolution of
relevant features leads to little confidence in identifying where
any overlap of thunderstorms, instability, and effective-layer shear
might support severe thunderstorms. However, if model guidance
begins to converge on potential scenarios, probabilistic delineation
may become warranted in subsequent forecasts.

..Marsh.. 07/11/2025

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ACUS48 KWNS 120731
SWOD48
SPC AC 120730

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0230 AM CDT Sat Jul 12 2025

Valid 151200Z - 201200Z

...DISCUSSION...
Several shortwave impulses are forecast to move through
low-amplitude upper troughing over the northern tier of the U.S.
during the Day 4-8 period. At the surface, a cold front is expected
to develop south/southeast across portions of the northern/central
Plains and Upper Midwest on Days 4-5/Tue-Wed. Given a moist and
unstable airmass ahead of this feature, some severe potential is
possible from the central Plains to the Upper Midwest. However,
medium range guidance shows large spread in the location and timing
of the front and any associated convection, resulting in low
predictability.

Later in the period, strong upper ridging will develop over the
Southeast. Some severe potential could continue eastward across the
Great Lakes to the Mid-Atlantic around Days 5-6/Wed-Thu as the
aforementioned cold front stalls in response to the building
Southeast ridge. However, large-scale ascent and deep-layer flow
will remain modest, and any severe potential would likely be driven
by mesoscale processes not well resolved at this time scale.

..Leitman.. 07/12/2025

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ACUS48 KWNS 130734
SWOD48
SPC AC 130732

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0232 AM CDT Sun Jul 13 2025

Valid 161200Z - 211200Z

...DISCUSSION...
Generally low-amplitude westerly flow will persist across the
northern tier of the CONUS during the Day 4-8 period. A couple of
shortwave impulses will migrate through westerly flow from the Upper
Midwest to the Great Lakes vicinity on Days 4-5/Wed-Thu and again
during the weekend. These features could support some severe
thunderstorm potential for parts of the Midwest/Great Lakes
vicinity, particularly on Days 4-5/Wed-Thu as a sagging cold front
stalls over the Great Lakes. However, prior convection and large
spread among various medium range guidance regarding timing and
location of these somewhat subtle features precludes severe
probabilities at this time.

Strong upper ridging will develop across the south-central and
southeast U.S. beginning around Day 6/Fri. Weak deep-layer flow
beneath the upper ridge and lack of large-scale forcing will limit
severe potential from the southern Plains into the Southeast.

..Leitman.. 07/13/2025

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ACUS48 KWNS 140830
SWOD48
SPC AC 140829

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0329 AM CDT Mon Jul 14 2025

Valid 171200Z - 221200Z

...DISCUSSION...
Upper ridging will build across the south-central and southeastern
U.S. during the Day 4-8 period. This will confine a series of
low-amplitude upper troughs to the northern tier of the U.S. along
the international border. Bouts of strong to severe thunderstorm
potential will be possible through the period as individual
shortwaves provide modestly enhanced mid/upper westerly flow from
the northern Plains to the Great Lakes vicinity. Given the generally low-amplitude nature the upper pattern across the northern U.S.
through at least Day 6 or 7/Sat or Sun, the main driver of severe
potential each day will be mesoscale features tied to prior days
convective evolution, not well resolved at longer time scales. As a
result, predictability is low.

..Leitman.. 07/14/2025

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ACUS48 KWNS 150653
SWOD48
SPC AC 150652

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0152 AM CDT Tue Jul 15 2025

Valid 181200Z - 231200Z

...DISCUSSION...
Low-amplitude/zonal westerly mid/upper flow is forecast across the
northern U.S. for much of the Day 4-8 period. At the same time, the
subtropical upper ridge/high over the Southeast will spread
westward, with larger-scale upper ridging developing over the
central U.S. late in the forecast period. Seasonally moist and
unstable conditions will exist for much of the CONUS east of the
Rockies. This will lead to daily thunderstorm activity, particularly
for parts of the northern/central Plains to the Midwest and
Mid-Atlantic regions. These areas will generally be on the north
side of the subtropic high and the southern fringes of any stronger
westerly flow near the international border. However, a lack of any
stronger forcing for ascent or notable surface features precludes
severe probabilities.

..Leitman.. 07/15/2025

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ACUS48 KWNS 160747
SWOD48
SPC AC 160745

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0245 AM CDT Wed Jul 16 2025

Valid 191200Z - 241200Z

...DISCUSSION...
A low-amplitude upper trough will move from the Great Lakes through
the Northeast during the Day 4-5/Sat-Sun period. Some enhanced
westerly flow aloft and a deepening surface low will accompany this
system. While forecast guidance varies with timing and location of
these features, some severe potential could develop from portions of
the Great Lakes to the Northeast/Mid-Atlantic over the weekend ahead
of a cold front. Details are still uncertain regarding where a
better chance for severe storms may develop, precluding
probabilities.

By early next week, upper ridging is forecast for much of the CONUS
east of the Rockies while an upper shortwave trough persists over
the Northwest. Late in the period, a shortwave impulse may eject
from the Northwest upper shortwave and move across the northern
Plains, posing some increasing risk for severe potential, though
confidence in this scenario remains too low to include an outlook
area at this time.

..Leitman.. 07/16/2025

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ACUS48 KWNS 170732
SWOD48
SPC AC 170731

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0231 AM CDT Thu Jul 17 2025

Valid 201200Z - 251200Z

...DISCUSSION...
Upper ridging will build across much of the CONUS during the Day 4-8
period. However, progressive, but low-amplitude westerly northern
stream flow will continue atop the upper ridge across the northern
tier of the U.S. This overall pattern will favor bouts of strong to
severe thunderstorms within west/northwesterly flow aloft from the
northern Plains into portions of the Midwest. However, given subtle
forcing mechanisms, this activity will be driven by mesoscale processes/features (MCVs from prior convection, modifying outflow
boundaries, etc) that are more uncertain at longer forecast times.
As such, predictability is too low for delineating areas at this
time.

..Leitman.. 07/17/2025

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ACUS48 KWNS 180855
SWOD48
SPC AC 180854

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0354 AM CDT Fri Jul 18 2025

Valid 211200Z - 261200Z

...DISCUSSION...
Medium-range guidance suggests that mid/upper ridging may remain a
prominent influence across much of the central and southeastern U.S.
through this period. Beneath its northern periphery, across parts
of the northern Great Plains into Upper Midwest and Great Lakes/Ohio
Valley, it appears that a seasonably moist boundary-layer may become characterized by moderate to strong diurnal destabilization each
day. However, forcing for ascent to support convective development
remains unclear, and might be largely dependent on sub-synoptic
features with low predictability, particularly at this extended
range.

Sizable spread exists among the output concerning synoptic features
within the westerlies, as well. However, there appears some signal
that a short wave perturbation, emerging either from the Pacific
Northwest or northwestern Canadian provinces early next week, could
be accompanied by an eastward advecting plume of elevated
mixed-layer air, low-level moistening and strengthening
lower/mid-tropospheric wind fields across parts of the Upper
Midwest/Great Lakes toward the St. Lawrence Valley/Northeast late
next Wednesday into Friday. It might not be out of the question
that this regime could become supportive of one or two sustained,
organized clusters of storms capable of producing swaths of damaging
winds and some hail.

..Kerr.. 07/18/2025

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ACUS48 KWNS 190848
SWOD48
SPC AC 190847

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0347 AM CDT Sat Jul 19 2025

Valid 221200Z - 271200Z

...DISCUSSION...
Medium-range guidance continues to indicate a belt of strengthening west-northwesterly flow across Ontario, Quebec and adjacent portions
of the U.S. Upper Midwest/Great Lakes toward the St. Lawrence Valley
and Northeast during the middle to latter portions of the coming
work week. This is forecast to occur as a notable mid-level low,
digging southeast of the Canadian Arctic latitudes over the next
couple of days, accelerates east-southeast of the Canadian Northwest Territories through the Hudson Bay vicinity and northern Quebec, to
the north of an increasingly prominent high becoming centered over
the Ohio/Tennessee Valleys by next Wednesday/Thursday.

Potential forcing for ascent associated with smaller-scale
perturbations emerging from initial troughing across the Pacific
Northwest, or other more subtle perturbations migrating around the
northwestern periphery of the high, before progressing eastward
along the southern periphery of this regime remain much more
unclear. However, guidance remains suggestive that moistening
beneath a plume of eastward advecting elevated mixed-layer air might
become supportive of destabilization conducive to the evolution of
progressive organized clusters of storms capable of producing swaths
of strong to severe gusts, in the presence of favorable shear.

..Kerr.. 07/19/2025

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ACUS48 KWNS 200847
SWOD48
SPC AC 200845

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0345 AM CDT Sun Jul 20 2025

Valid 231200Z - 281200Z

...DISCUSSION...
The latest medium-range output offers little change from prior runs
concerning the general large-scale pattern evolution during the
middle to latter portion of the coming work week. It still appears
that a fairly significant mid-level low currently emerging from the northwestern Canadian Arctic latitudes will slowly progress across
and east-southeast of the Hudson Bay vicinity, to the north of an
increasingly prominent mid-level high evolving across the Ohio
Valley. As this contributes to a belt of strengthening westerly to northwesterly flow between the two features, it appears that
low-level moistening in a corridor beneath the southern periphery of
this regime will support substantive destabilization, and increasing
potential for organized strong to severe thunderstorm development.

The extent to which this corridor evolves south of the international
border, across parts of the Upper Midwest and adjacent Great Lakes
region toward the St. Lawrence Valley/New England remains at least a
bit unclear. Adding to this uncertainty, forcing for this potential
convective development will be largely associated with sub-synoptic perturbations with low predictability at this extended time frame.

..Kerr.. 07/20/2025

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ACUS48 KWNS 210854
SWOD48
SPC AC 210853

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0353 AM CDT Mon Jul 21 2025

Valid 241200Z - 291200Z

...DISCUSSION...
Medium-range models indicate that mid-level ridging, initially
centered over the Ohio Valley, will weaken late this work week
through next weekend, as flow undergoes substantive amplification
upstream. This appears likely to include a significant short wave
trough digging southeast of the Aleutians, accompanied by lower/mid-tropospheric cyclogenesis across the northeastern Pacific.
Part of a higher latitude blocking pattern, little subsequent
movement of this cyclone is forecast through early next week, as an
expansive, prominent mid-level ridge also evolves in the downstream
lower latitudes, across much of the Intermountain West, Rockies and
Great Plains into mid and lower Mississippi Valley.

However, as a notable mid-level low continues slowly east of Hudson
Bay, across northern Quebec and Newfoundland and Labrador, a belt of
seasonably strong westerly mid/upper flow may be maintained across
Ontario and Quebec this Thursday through Friday. Along the
favorably sheared southern fringe of this regime, seasonably moist
low-level air advecting ahead of a stalled to southward advancing
frontal zone may contribute to sufficient destabilization for the
evolution of organizing thunderstorm clusters capable of producing
swaths of damaging wind gusts. The extent to which this may impact
U.S. portions of the Great Lakes into New England remains unclear.

It might not be out of the question that a similar type regime could
evolve beneath developing northwesterly mid-level flow, from the
North Dakota/Minnesota international border area into the Upper
Midwest/Great Lakes late next weekend into early next week. Current
guidance is still suggestive that this is a lower probability, but
this could be due to the low predictability of the pertinent
features at this extended range.

..Kerr.. 07/21/2025

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ACUS48 KWNS 220852
SWOD48
SPC AC 220850

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0350 AM CDT Tue Jul 22 2025

Valid 251200Z - 301200Z

...DISCUSSION...
Medium-range guidance suggests that strongest destabilization
(including large potential instability) by next weekend into early
next week will become focused once again from the lee of the
northern U.S. Rockies across and northeast of the middle and lower
Missouri Valley into Upper Midwest. This is forecast to be
supported by seasonably high boundary-layer moisture content,
beneath a plume of steepening mid-level lapse rates near the
southwestern periphery of an increasingly northwesterly regime,
between building mid-level ridging along/east of the Rockies and
another significant low digging southeast of the central Canadian
Arctic latitudes through Hudson Bay.

By next Sunday into Monday, it appears possible that this
environment could become supportive of the evolution of one or two
organizing, east-southeastward propagating convective systems.
However, the forcing for any such development remains unclear, and
probably will be tied to sub-synoptic perturbations with very low predictability at this extended range.

..Kerr.. 07/22/2025

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ACUS48 KWNS 230901
SWOD48
SPC AC 230900

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CDT Wed Jul 23 2025

Valid 261200Z - 311200Z

...DISCUSSION...
Medium-range guidance continues to indicate that initially zonal
westerlies near the central Canadian/U.S. border will undergo
considerable amplification by the early to middle portion of next
week. This is forecast to occur as a significant mid-level low digs
southeast of the Aleutians, before gradually pivoting eastward and northeastward across the northeastern Pacific. To the east of
building downstream ridging across the Canadian Prairies, another
significant low emerging from the Arctic is forecast to dig into and
across the Hudson Bay vicinity. Before broad cyclonic flow to the
south of this latter feature encompasses much of the Upper Midwest
and Great Lakes through Northeast by the end of the period, a
prominent mid-level high may redevelop west-northwest of the
Southeast through central Great Plains.

As this regime evolves, it appears that a plume of elevated
mixed-layer air emerging from the Intermountain West will contribute
to steepening mid-level lapse rates across parts of the northern
Great Plains, then eastward and southeastward beneath increasingly northwesterly mid-level flow across the Upper Midwest/Great Lakes
and parts of the Ohio Valley. Beneath this regime seasonably high boundary-layer moisture content northeast of the middle and lower
Missouri Valley likely will contribute to moderate to strong
potential instability.

Based on the latest ECENS and GEFS, rising mid-level heights are
forecast within broadly anticyclonic flow across the northern Great
Plains and Upper Midwest, through the international border vicinity,
on Saturday. There appears a general signal that a subtle
perturbation may progress through this regime, across the
Minnesota/Wisconsin vicinity, Sunday through Sunday night. As it
does, the environment could become potentially conducive to the
evolution of a substantive organized convective system, before
mid-level heights begin to gradually fall across the upper Great
lakes into Upper Midwest during the early to middle portion of next
week. This could be accompanied by continuing potential for renewed
strong to severe thunderstorm development, with a tendency to
propagate eastward and southeastward into the Ohio Valley and
possibly parts of the Northeast. However, much of this may
significantly depend on interacting sub-synoptic developments with
low predictability in the extended range.

..Kerr.. 07/23/2025

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ACUS48 KWNS 240900
SWOD48
SPC AC 240858

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CDT Thu Jul 24 2025

Valid 271200Z - 011200Z

...DISCUSSION...
Models indicate substantive amplification within an initially zonal
belt of westerlies across the northern mid-latitude Pacific during
the coming days, with several embedded closed lows evolving,
including one by the beginning of the period across the northeastern
Pacific, on the leading edge of an increasingly blocked regime.
Downstream, as another significant low, emerging from the Arctic
latitudes, turns across the eastern Northwest Territories into and
through Hudson Bay, mid/upper ridging is forecast to build through
much of the Canadian Prairies. Gradually, models indicate that
amplified ridging will encompass much of interior North America,
across and east of the Rockies through the mid to latter portions of
next week, while amplified troughing evolves further downstream,
across the eastern Canadian provinces, the Great Lakes and
Northeast.

The evolution of this regime appears likely to be accompanied by a
plume of steepening mid-level lapse rates overspreading the northern
U.S. Great Plains and adjacent portions of southern Canada, toward
the Upper Midwest/Great Lakes, during the early to middle portion of
next week, before becoming suppressed southwestward. Aided by the
return of seasonably high boundary layer moisture content to areas
near and northeast of the lower through middle Missouri Valley, it
appears that this will contribute to a broad area of moderate to
large potential instability.

This environment may become conditionally supportive of the
evolution of longer-lived organized thunderstorm clusters, with
potential to produce swaths of damaging wind gusts across parts of
the northern Great Plains, Upper Midwest and Great Lakes into the
Ohio Valley and perhaps parts of the Northeast. However, prior to
more substantive mid/upper trough amplification, and the southward
advancement of a cold front into much of the northeastern U.S. by
the middle of next week, the evolution of any such cluster, south of
the international border, will likely largely depend on subtle short
wave perturbations progressing through the larger scale ridging.
Given the low predictability of these features at this extended
range, and the uncertain impacts of their associated convection and
outflow on subsequent destabilization, severe probabilities remain
low due to the uncertainties.

..Kerr.. 07/24/2025

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ACUS48 KWNS 250856
SWOD48
SPC AC 250855

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0355 AM CDT Fri Jul 25 2025

Valid 281200Z - 021200Z

...DISCUSSION...
The strongest mid-level flow will move from the Upper Midwest into
the Northeast this weekend into the middle of next week. As this
occurs, a surface boundary will slowly sag into the central Plains
and Ohio Valley. Given the very moist airmass to the south of the
boundary, strong to potentially severe storms are possible along the
boundary at least into the middle of next week. With the stronger
flow/shear displace north of the boundary and model differences in
the location, uncertainty remains too high for highlights.

Farther west, moisture will be pushed up against parts of the
northern Rockies and adjacent High Plains. Between the terrain and
shortwave troughs moving through the central U.S. ridge, it is
possible strong to severe storms could develop and progress along
the surface boundary into greater areas of moisture/buoyancy in the
Plains. Given the dependency on the low-predictability shortwaves,
it is not clear where the greatest risk will be from the High Plains
into the Plains through the middle of next week.

By the end of next week, model guidance suggests a general trend of
continued upper ridge building into Plains. Stronger mid-level winds
will remain in parts of the Northeast with additional shortwave
perturbations moving through parts of the northern Rockies. Severe
risk along the boundary should decrease as it becomes further
removed from the stronger flow. Though predictability is low
regarding the shortwave troughs, some severe risk could develop in
parts of the northern Rockies.

..Wendt.. 07/25/2025

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ACUS48 KWNS 260853
SWOD48
SPC AC 260852

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0352 AM CDT Sat Jul 26 2025

Valid 291200Z - 031200Z

...DISCUSSION...
The upper-level pattern over the next week will generally feature an
elongated upper ridge centered over the Southeast stretching into
the Northwest. In the Northeast and nearby vicinity, upper-level
cyclonic flow will be present. A belt of stronger mid-level winds
will accompany that trough. Along the West Coast, a lower amplitude
shortwave trough will slowly move northward along the coast. As the
Northeast trough continues to shift east into late next week and the
weekend, the surface cold front will continue to be pushed
southward. Thunderstorms are likely to occur along and near this
boundary given the hot and moist airmass to its south. While some
severe risk could accompany this activity, stronger mid-level flow
will become displaced farther and farther northward from the
boundary each day. This leads to uncertainty in the overall
magnitude of the severe threat from the Ohio Valley into the Mid-South/Southeast.

Additional storms, with some severe potential could occur in parts
of the Northwest with the approach of greater mid-level moisture and
the trough. Again, the placement and intensity of this activity is
uncertain. Even with a decrease in low-level moisture behind the
surface front, remaining moisture will be pushing into the terrain
of the northern Rockies. Along with some mid-level flow enhancement,
strong to severe storms would be possible.

..Wendt.. 07/26/2025

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ACUS48 KWNS 270828
SWOD48
SPC AC 270827

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0327 AM CDT Sun Jul 27 2025

Valid 301200Z - 041200Z

...DISCUSSION...
The general upper-level pattern over the next week will feature a
trough in the Northeast, a ridge over much of the southern U.S. and
Plains, and a weak trough off the West Coast. The Northeastern
trough will weaken with time, before moving out of the region around
next weekend. Models eventually develop a shortwave trough in the
West, but this signal has been inconsistent in the past several
runs. At the surface, high pressure will build into the Great Lakes
and Northeast. This will progressively push a cold front farther
south and west with time.

While some severe risk is possible along the cold front, shear and
buoyancy will be diminished with each successive day. With the front
pushing modest moisture into the Rockies, convection is possible
each day next week. Strong to potentially severe storms may occur
with this activity, but weak shear beneath the upper ridge makes it
unclear where the most intense storms would be. Furthermore,
repeated days of convection will at some point adversely affect the
quality of the low-level airmass. Predictability remains too low for highlights.

..Wendt.. 07/27/2025

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ACUS48 KWNS 280850
SWOD48
SPC AC 280849

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0349 AM CDT Mon Jul 28 2025

Valid 311200Z - 051200Z

...DISCUSSION...
By late next week, the upper-level trough in the Northeast will be
moving into the Canadian Maritimes. In its wake, high pressure at
the surface will build into the Upper Midwest/Ohio Valley. This will
push the surface front farther south each day through the weekend.
In the West, cyclonic flow will tend to weaken over time. The
surface front will be pushed up against the Rockies. Model guidance
shows progressively lower amounts of buoyancy south of the front in
the Southeast, likely due to repeated days of convection. This
activity will also become farther removed from stronger shear. Winds
with some upslope component with weak/modest westerlies aloft could
allow for some severe risk near the Rockies and adjacent High
Plains, but the overall weak shear and potential for sequential
convective days leading to a poor quality airmass suggest the threat
is like to remain marginal. Predictability of organized severe
weather remains low.

..Wendt.. 07/28/2025

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ACUS48 KWNS 290856
SWOD48
SPC AC 290855

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0355 AM CDT Tue Jul 29 2025

Valid 011200Z - 061200Z

...DISCUSSION...
Surface high pressure will build into the eastern CONUS this weekend
which will push a cold front south to near the Gulf Coast. Limited
instability in the wake of this front should limit severe weather
potential for many areas east of the Plains. As the upper-level
ridge weakens across the Plains by the end of the weekend, more
zonal flow across the Mountains will lead to weak lee troughing. Southerly/southeasterly flow will result in some instability across
the High Plains. Mid-level flow will not be that strong, but should
be sufficient for some isolated severe weather potential. However, predictability decreases significantly once the ridge breaks down
and therefore, it is unclear when or where a more organized severe
weather threat may occur.

..Bentley.. 07/29/2025

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ACUS48 KWNS 300844
SWOD48
SPC AC 300842

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0342 AM CDT Wed Jul 30 2025

Valid 021200Z - 071200Z

...DISCUSSION...
Surface high pressure will build into the eastern CONUS this weekend
and usher in an extended period of cooler and less humid weather for
much of the eastern CONUS with reduced severe weather chances. Some
severe weather chances will remain from the central High Plains to
the northern Plains where low-level moisture is expected to remain.
Several weak embedded mid-level shortwave troughs may result in some thunderstorm activity from the central to northern High Plains amid
moderate to strong instability. A few severe storms are possible
early next week with any of these passing troughs.

There is some signal that a more organized severe weather threat
could materialize by the middle of next week as strong instability
builds across the northern Plains and stronger mid-level troughing
and flow becomes more prevalent across the region. However,
predictability is low within this low-amplitude pattern. There is
not much consensus for the overall pattern beyond D6/Monday and
therefore, no severe weather probabilities are warranted at this
time.

..Bentley.. 07/30/2025

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ACUS48 KWNS 310909
SWOD48
SPC AC 310908

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0408 AM CDT Thu Jul 31 2025

Valid 031200Z - 081200Z

...DISCUSSION...
The extended range will primarily feature the potential for
Northwest flow severe across the Plains. Moderate to strong
instability is expected to build across the central Plains and into
parts of the northern Plains. A mid-level trough off the California
coast at the beginning of the period is forecast to move northward
and eventually into southern Canada. Beyond this time, the forecast
uncertainty increases. Both the ECMWF and GFS suggest some troughing
will advance toward the Midwest/Great Lakes, but the amplitude
varies. This will have significant impact on the potential locations
of severe weather and the potential for the threat to extend east of
the Plains/Upper Midwest. Regardless of the exact solution of the
extended range pattern, moderate mid-level flow will likely
overspread much of the northern Plains and potentially portions of
the central Plains. Where this mid-level flow interacts with the
developing instability and thunderstorms, some severe weather is
possible. However, the uncertain timing and evolution of the pattern
makes identification of these corridors challenging and precludes
severe weather probabilities at this time.

..Bentley.. 07/31/2025

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ACUS48 KWNS 010854
SWOD48
SPC AC 010852

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0352 AM CDT Fri Aug 01 2025

Valid 041200Z - 091200Z

...DISCUSSION...
...Monday/Day 4 to Wednesday/Day 6...
Early in the week, a mid-level trough is forecast to remain over the Mississippi Valley, as a ridge builds northward across the High
Plains. To the east of the ridge, moderate to strong instability is
forecast to develop Monday afternoon over parts of the High Plains.
Isolated severe storms that form near the instability axis could
pose a severe threat from the afternoon into the evening, but
limited large-scale ascent should keep any severe threat localized.

On Tuesday, a shortwave mid-level trough is forecast to move through
the northern High Plains. Thunderstorms that form ahead of the
trough in the afternoon could be associated with an isolated severe
threat. The models suggest that this feature will move into northern
Plains Tuesday night into Wednesday. This could result in scattered thunderstorm development early in the day on Wednesday over parts of
the eastern Dakotas. The trough is forecast to exit the region by
Wednesday afternoon. In the wake of the trough, isolated
thunderstorm development could re-develop across the northern Plains
late Wednesday afternoon into the evening. These storms could be
associated with isolated severe gusts and hail.

...Thursday/Day 7 and Friday/Day 8...
On Thursday, a shortwave trough is forecast to move into the
northern Plains. Ahead of the trough, a moist and unstable airmass
should be in place by afternoon. Some model solutions suggest that a
convective cluster will develop Thursday evening over parts of the
eastern Dakotas, with the storms moving east-southeastward into the
upper Mississippi Valley during the overnight period. Considering
that moderate deep-layer shear is forecast, these storms would be
associated with a threat for hail and severe wind gusts. However, predictability at this extended range is low, mainly due to issues
concerning the trough timing and parameter magnitudes.

A severe threat will again be possible on Sunday across parts of the
northern Plains, as a mid-level trough develops and approaches the
region. On Sunday, predictability again is low due to similar
issues.

..Broyles.. 08/01/2025

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ACUS48 KWNS 012112
SWOD48
SPC AC 012110

Day 4-8 Convective Outlook RESENT 1
NWS Storm Prediction Center Norman OK
0410 PM CDT Fri Aug 01 2025

Valid 041200Z - 091200Z

...DISCUSSION...
...Monday/Day 4 to Wednesday/Day 6...
Early in the week, a mid-level trough is forecast to remain over the Mississippi Valley, as a ridge builds northward across the High
Plains. To the east of the ridge, moderate to strong instability is
forecast to develop Monday afternoon over parts of the High Plains.
Isolated severe storms that form near the instability axis could
pose a severe threat from the afternoon into the evening, but
limited large-scale ascent should keep any severe threat localized.

On Tuesday, a shortwave mid-level trough is forecast to move through
the northern High Plains. Thunderstorms that form ahead of the
trough in the afternoon could be associated with an isolated severe
threat. The models suggest that this feature will move into northern
Plains Tuesday night into Wednesday. This could result in scattered thunderstorm development early in the day on Wednesday over parts of
the eastern Dakotas. The trough is forecast to exit the region by
Wednesday afternoon. In the wake of the trough, isolated
thunderstorm development could re-develop across the northern Plains
late Wednesday afternoon into the evening. These storms could be
associated with isolated severe gusts and hail.

...Thursday/Day 7 and Friday/Day 8...
On Thursday, a shortwave trough is forecast to move into the
northern Plains. Ahead of the trough, a moist and unstable airmass
should be in place by afternoon. Some model solutions suggest that a
convective cluster will develop Thursday evening over parts of the
eastern Dakotas, with the storms moving east-southeastward into the
upper Mississippi Valley during the overnight period. Considering
that moderate deep-layer shear is forecast, these storms would be
associated with a threat for hail and severe wind gusts. However, predictability at this extended range is low, mainly due to issues
concerning the trough timing and parameter magnitudes.

A severe threat will again be possible on Sunday across parts of the
northern Plains, as a mid-level trough develops and approaches the
region. On Sunday, predictability again is low due to similar
issues.

..Broyles.. 08/01/2025

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ACUS48 KWNS 020902
SWOD48
SPC AC 020900

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CDT Sat Aug 02 2025

Valid 051200Z - 101200Z

...DISCUSSION...
...Tuesday/Day 4 to Thursday/Day 6...
On Tuesday, a mid-level ridge is forecast to remain over the central
Rockies, as a subtle shortwave trough moves into the northern
Plains. Thunderstorm development will be possible near and ahead of
the trough across parts of the Dakotas during the afternoon and
evening. Model forecasts suggest that the environment will support
severe storms, mainly across western and central South Dakota where
an axis of instability and moderate deep-layer shear is forecast.
Isolated large hail and severe gusts are expected to be the primary
threats.

On Wednesday, the shortwave trough is forecast to move eastward into
the upper Mississippi Valley, outrunning the moist and unstable
airmass over the central and northern Plains. Isolated storms could
develop in the wake of the trough over parts of the region, but the
negative effects of a ridge aloft will likely keep any severe threat
localized.

The mid-level ridge is forecast to move eastward into the upper
Mississippi Valley on Thursday, as flow become west-southwesterly in
its wake over the northern Plains. Strong instability could develop
across parts of the region, mainly due to surface dewpoints in the
70s F. Although large-scale ascent is forecast to remain weak in
most areas, a few storms with hail and isolated severe gusts could
develop in the afternoon and evening.

...Friday/Day 7 and Saturday/Day 8...
On Friday, a mid-level shortwave ridge is forecast to move across
the north-central U.S., as a trough moves into the northern Rockies.
Strong instability is forecast to develop by afternoon across much
of the northern Plains and upper Mississippi Valley. Isolated
thunderstorms are expected across parts of the region as surface
temperatures become maximized in the mid to late afternoon. Although
a severe threat will be possible, the presence of the mid-level
ridge could be problematic for a greater severe threat.

On Saturday, a mid-level trough and an associated jet max, is
forecast to move eastward into the northern Plains. Thunderstorm
development will be possible ahead of the trough from the eastern
Dakotas into the upper Mississippi Valley. It appears that the
environment should support a severe threat due strong instability
and substantial deep-layer shear. However, the projected scenario
remains uncertain due to the extended range.

..Broyles.. 08/02/2025

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ACUS48 KWNS 030859
SWOD48
SPC AC 030858

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CDT Sun Aug 03 2025

Valid 061200Z - 111200Z

...DISCUSSION...
...Wednesday/Day 4 to Friday/Day 6...
A large-scale mid-level anticyclonic flow pattern will be in place
over much of the central and western U.S during the mid week. At the
surface, a moist and unstable airmass is forecast over the central
and northern Plains. Within the broader scale flow, a shortwave
ridge is forecast to move across the northern Plains from Wednesday
into Thursday. In spite of relatively weak large-scale ascent,
isolated thunderstorm development will be possible on Wednesday and
Thursday as instability becomes maximized in the late afternoon and
early evening. Moderate deep-layer shear should support a potential
for isolated severe gust and hail.

As the mid-level ridge moves eastward during the day on Thursday,
flow is forecast to become southwesterly across the northern High
Plains. Thunderstorms that develop in eastern Montana and western
North Dakota Thursday evening could be associated with a severe
threat. Isolated large hail and severe gusts will be possible. Model
forecasts suggest an isolated severe threat will again be possible
in the northern Plains on Friday, in the wake of the exiting ridge.

...Saturday/Day 7 and Sunday/Day 8...
On Saturday, a mid-level trough is forecast to move into the
northern High Plains, as flow remains southwesterly from the Dakotas
into the upper Mississippi Valley. Model forecasts develop a
relatively large cluster of thunderstorms Saturday evening ahead of
the trough from northwestern Minnesota into eastern South Dakota.
The models also have strong instability and moderate deep-layer
shear in place ahead of the trough within the favored convective
zone. This could support a potential for supercells with large hail
and severe wind gusts. However, the steeper lapse rates are forecast
to remain further south across the mid Missouri Valley, suggesting
there is still some uncertainty concerning the magnitude of the
severe threat.

On Sunday, the severe threat is forecast to shift southeastward as a
front moves across the region. The favored corridor would be along
an axis of moderate instability from northeast Nebraska to
northwestern Wisconsin. This position of the front and instability
axis should be determined by the timing of the mid-level system,
which is still considerably uncertain.

..Broyles.. 08/03/2025

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ACUS48 KWNS 040904
SWOD48
SPC AC 040903

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0403 AM CDT Mon Aug 04 2025

Valid 071200Z - 121200Z

...DISCUSSION...
...Thursday/Day 4 to Saturday/Day 6...
During the late week time-frame, a mid-level trough is forecast to
develop over the Pacific Northwest and move eastward into the
northern Plains. As the system approaches, a moist and unstable
airmass is forecast across the northern Plains and upper Mississippi
Valley. On Thursday, a lead shortwave trough is forecast to move
across the northern Plains. Large-scale ascent associated with the
trough could result in a cluster of storms with an isolated severe
threat from Thursday evening into the overnight period. Isolated to
scattered thunderstorms may again develop Friday afternoon and
evening, as the exit region of a mid-level jet moves across the
northern Plains. As instability becomes maximized on Friday
afternoon, a severe threat will be possible across parts of the
Dakotas and Minnesota. Large hail and severe gusts will be the
primary threats. The models are in reasonably good agreement on the
timing of the mid-level system. For this reason, have added a 15
percent into the northern Plains to coincide with the projected
locations of the instability axis and mid-level jet.

On Saturday, the mid-level trough is forecast to move into the
northern Plains, as a belt of southwesterly flow shifts eastward
across the Upper Midwest. Thunderstorm development will be possible
in the afternoon and evening, to the east of a front within an
unstable airmass in the upper Mississippi Valley. Moderate
deep-layer shear will again support an isolated severe threat across
the region.

...Sunday/Day 7 and Monday/Day 8...
The front is forecast to move southeastward into the upper
Mississippi Valley on Sunday. This will favor thunderstorm
development along a corridor from Iowa northeastward into Wisconsin,
where an isolated severe threat will be possible in the afternoon
and evening. On Monday, forecasts suggest the instability axis will
remain in a similar location. For this reason, a severe threat could
again affect this same corridor. Due to the extended range in the
forecast, there is some uncertainty concerning this scenario early
next week.

..Broyles.. 08/04/2025

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ACUS48 KWNS 050900
SWOD48
SPC AC 050858

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CDT Tue Aug 05 2025

Valid 081200Z - 131200Z

...DISCUSSION...
...Friday/Day 4 to Sunday/Day 6...
On Friday, a mid-level trough and an associated speed max is
forecast to move into the northern Plains. At the surface, a moist
airmass will be in place over much of the northern Plains, where
surface dewpoints are likely to be in the lower to mid 70s F. As
surface temperatures warm during the day, moderate to strong
instability is expected to develop. Along the northwestern edge of
this unstable airmass, thunderstorms should form in parts of central
and eastern North Dakota. Convective coverage is forecast to expand
southward into South Dakota during the evening. Moderate to strong
deep-layer shear associated with the speed max will be favorable for
a severe threat during the afternoon and evening. Supercells with
large hail, severe wind gusts and a tornado threat will be possible.


On Saturday, the mid-level trough and associated cold front are
forecast to move eastward into the upper Mississippi and mid
Missouri Valleys. Thunderstorms are forecast to be ongoing along and
near the front during the morning, with additional thunderstorm
development taking place further southeast in the afternoon.
Moderate instability and deep-layer shear is forecast across much of
the region, suggesting that a severe threat will again be possible.
There is some uncertainty as to how much the airmass will be
negatively affected by the morning convection. Also, model forecasts
suggest that the greatest convective potential will be during the
overnight period on Saturday. For this reason, will not add a threat
area for Saturday at this time.

On Sunday, a mid-level trough is forecast to move across the
north-central U.S., being positioned from the northern Plains to the
central Rockies by afternoon. A moderately unstable airmass is
forecast further to the east, from the upper Mississippi Valley
southward into the mid Missouri Valley. An isolated severe threat
will be possible Sunday afternoon along and near the instability
axis. However, the mid-level trough is forecast to remain well to
the west of the instability axis, which should limit large-scale
ascent over the unstable airmass, helping to keep any severe threat
isolated.

...Monday/Day 7 and Tuesday/Day 8...
A low-amplitude mid-level trough is forecast to move into the upper
Mississippi Valley on Monday, and into the western Great Lakes on
Tuesday. Further southwest, a mid-level low is forecast across the
central Plains. Thunderstorms will be possible on Monday and Tuesday
afternoon, along the northern edge of a moist airmass from the
central Plains northeastward to the Great Lakes. Model forecasts
suggest that deep-layer shear will be relatively weak. Although
convective coverage and any associated severe threat will likely
remain isolated, a few marginally severe storms could occur in areas
that heat up the most.

..Broyles.. 08/05/2025

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ACUS48 KWNS 060855
SWOD48
SPC AC 060854

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0354 AM CDT Wed Aug 06 2025

Valid 091200Z - 141200Z

...DISCUSSION...
...Saturday/Day 4 to Monday/Day 6...
A mid-level trough will move across the northern Plains on Saturday,
as a cold front advances southeastward into the upper Mississippi
and mid Missouri Valleys. Moderate to strong instability should be
in place ahead of the front by afternoon from eastern Nebraska
northeastward into Wisconsin. Thunderstorm development is expected
to take place along parts of the front from the afternoon into the
evening, with the greatest convective coverage over the upper
Mississippi Valley. A few storms could be severe, with large hail
and isolated damaging wind gusts expected to be the primary threats.


On Sunday, another mid-level trough is forecast to move into the
central and northern Plains, as a moist and unstable airmass remains
in place ahead of the front from the mid Missouri Valley
northeastward upper Mississippi Valley. Thunderstorms will again be
possible ahead of the trough near an axis of moderate instability
during the afternoon and evening. Some model forecasts suggest the
strongest instability will not be co-located with the greatest
convective potential. Although a severe threat may develop across
parts of the region, this would negatively affect severe threat
magnitude.

The mid-level trough is forecast to shift eastward across the
north-central U.S. on Monday, as a cold front advances southeastward
across the central Plains and Upper Midwest. Isolated severe
thunderstorms will again be possible ahead of the front near an axis
of moderate instability. However, large-scale ascent will be
somewhat limited across much of the region, suggesting the
convective potential and resulting severe threat should remain
isolated.

...Tuesday/Day 7 and Wednesday/Day 8...
From Tuesday into Wednesday, the mid-level trough and an associated
cold front is forecast to advance eastward from the north-central
U.S. into the Northeast. Along and ahead of the front each afternoon
and evening, strong thunderstorms will be possible. However, the
models are forecasting less instability and a more disorganized
pattern compared to previous days, suggesting that any severe threat
will remain localized.

..Broyles.. 08/06/2025

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ACUS48 KWNS 070845
SWOD48
SPC AC 070843

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0343 AM CDT Thu Aug 07 2025

Valid 101200Z - 151200Z

...DISCUSSION...
...Sunday/Day 4 to Tuesday/Day 6...
A persistent shortwave mid-level trough is forecast to remain over
the central U.S. from Sunday to Tuesday. During this time period, a
moist and unstable airmass is forecast to be in place from the
central Plains northeastward into the Great Lakes. It appears that
large-scale ascent will be weak across most of this airmass, which
will result in limited convective coverage. Although instability and
deep-layer shear should be sufficient for an isolated severe threat
each afternoon, mainly in areas that heat up the most, any potential
should remain localized.

Further north into the northern Plains, low-level moisture is
forecast to increase by midweek. In response, a moderately unstable
airmass could develop by Tuesday afternoon. In spite of this, warm
air aloft and limited large-scale ascent should keep convective
coverage very isolated. This will likely limit any related severe
threat.

...Wednesday/Day 7 and Thursday/Day 8...
From Wednesday into Thursday, a mid-level trough is forecast to move
across the northwestern U.S. Ahead of this system, a cold front is
forecast to advance southeastward across the northern Plains.
Thunderstorms would be possible near the front across the Dakotas
Wednesday afternoon, and in the upper Mississippi Valley Thursday
afternoon. An isolated severe threat would be possible for both
days. However, details concerning any potential scenario, including
the timing of the front, is highly uncertain at this time.

..Broyles.. 08/07/2025

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ACUS48 KWNS 080823
SWOD48
SPC AC 080822

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0322 AM CDT Fri Aug 08 2025

Valid 111200Z - 161200Z

...DISCUSSION...
A weak upper trough over the north-central U.S. on Monday/D4 will
move into the upper Great Lakes on Tuesday/D5, then eject into
eastern Canada by Wednesday/D6. From D6 through Friday/D8, another
wave is forecast to develop over the Pacific Northwest, and move
across the northern Rockies.

At the surface, a moist air mass will remain over much of the
central and eastern states, with minimal surface focus. However,
daily areas of thunderstorms, some with gusty winds, are likely to
occur from the upper Great Lakes to the southern Plains for
Monday/D4 into Tuesday/D5, and then into the OH/TN Valleys and
Northeast thereafter.

Perhaps by D7/D8, the northern Rockies trough will interact with
stronger instability over the northern Plains with a wind or hail
threat, but predictability is low this far out for such a minimal
system.

..Jewell.. 08/08/2025

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ACUS48 KWNS 090819
SWOD48
SPC AC 090817

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0317 AM CDT Sat Aug 09 2025

Valid 121200Z - 171200Z

...DISCUSSION...
A shortwave trough will move from the northern Plains into the
Northeast during the Tuesday/D4 to Wednesday/D5 time frame, with an
initial push of drier air southward across the Midwest/Great Lakes.
Stronger instability is forecast to redevelop by Thursday/D6 and
beyond as a low-amplitude upper trough moves across the northern
Rockies and Plains and increasing southerly low-level winds bring
dewpoints into the mid 70s F northward across the Mid MO/Upper MS
Valleys. This may yield one or more severe events across parts of
the northern Plains to upper MS Valley, but confidence is low.

..Jewell.. 08/09/2025

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ACUS48 KWNS 100825
SWOD48
SPC AC 100824

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0324 AM CDT Sun Aug 10 2025

Valid 131200Z - 181200Z

...DISCUSSION...
From Wednesday/D4 into Thursday/D5, a shortwave trough is forecast
to move from the Pacific Northwest across MT and over the far
northern Plains, with an upper speed max developing into southern SK
and MB. In advance of this trough, a leading trough affecting the
Great Lakes region will also lift northeastward, with height rises
and a warming pattern across parts of the Plains and upper Midwest.
The combination of increasing dewpoints and the upper trough
glancing the region may result in some manner of severe risk late
Thursday/D5, and most likely from parts of ND into northern MN, and
in evening/overnight MCS form. Future model trends will be monitored
for a possible risk area.

From Friday/D6 onward, predictability decreases with the motion of
the aforementioned upper wave. However, large instability is likely
to again build across the Mid MO/Upper MS Valleys, and at least
sporadic severe storms cannot be ruled out from the northern High
Plains eastward toward the Upper Great Lakes.

..Jewell.. 08/10/2025

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ACUS48 KWNS 110853
SWOD48
SPC AC 110852

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0352 AM CDT Mon Aug 11 2025

Valid 141200Z - 191200Z

...DISCUSSION...
On Thursday/D4, a shortwave trough is forecast to move from MT into
the northern Plains, with primary upper low well to the north. A
surface trough and cold front should push eastward across the
Dakotas as well, and extend roughly from MN into NE by Friday/D5
morning. Model spread is high regarding the amount of moisture
return and instability, with some models likely over-estimating real instability. In any case, storms appear most likely from ND into
northern MN, beneath 50+ kt midlevel westerlies. As such, a 15%
severe area has been introduced.

This wave will progress east/northeastward on Friday/D5, with a
front trailing southwestward perhaps from Lake Superior across WI/MN
and toward NE. A moist and unstable air mass will remain near and
south of any such boundary, but the position of said boundary may
depend on storms from the previous night, or possibly a continuation
of such storms. Predictability is therefore low on Friday/D5.

Beyond this time frame, it appears the storm track will shift
northward into Canada, with upper ridging over much of the CONUS.

..Jewell.. 08/11/2025

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ACUS48 KWNS 120812
SWOD48
SPC AC 120811

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0311 AM CDT Tue Aug 12 2025

Valid 151200Z - 201200Z

...DISCUSSION...
From Friday/D4 into Saturday/D5, an upper low will move from
Manitoba across Hudson Bay and into Quebec. Moderate midlevel
westerlies will exist over the far northern Plains to Upper Great
Lakes during this period, with gradual weakening. An upper high will
also be centered over the mid MS Valley, while a weak midlevel
trough with cool air aloft slowly departs the Great Basin.

At the surface, a front is forecast to stall on Friday/D4 from
northern NE across southern MN and into northern WI, with a moist
and unstable air mass remaining to the south. This front will remain
over roughly the same zone into Saturday/D5, and perhaps as late as
Sunday/D6.

Given that the moist and unstable air mass will persist over parts
of the northern Plains/Upper MS Valley, and minor ripples in the
flow are hinted at by several models, areas of storms are expected.
However, storm/MCS corridors are difficult to pinpoint this far out.
In general, the area from SD into WI will bear watching for wind
potential.

From Sunday/D6 onward, an upper ridge is expected to build over much
of the western and central states, with a reduction in severe
potential overall.

..Jewell.. 08/12/2025

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ACUS48 KWNS 130846
SWOD48
SPC AC 130844

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0344 AM CDT Wed Aug 13 2025

Valid 161200Z - 211200Z

...DISCUSSION...
During the Saturday/D4 to Sunday/D5 time frame, a weak midlevel wave
may affect the far northern Plains to upper Great Lakes, rounding
the building upper ridge. Meanwhile, a boundary will exist roughly
from ND/MN into MI, with latitudinal uncertainty. A moist air mass
will remain across this zone, with periodic storm complexes
possible. Predictability is low but at least some wind risk may
develop across portions of this zone.

For the rest of the period through at least Wednesday/D8, a large
upper ridge is forecast to build over much of the West/Rockies, with
minimal severe risk.

..Jewell.. 08/13/2025

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