• DAY1SVR: Day 1 Convective Outlook Resent 1

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Tue Feb 18 21:35:35 2025
    ACUS01 KWNS 182135
    SWODY1
    SPC AC 182134

    Day 1 Convective Outlook RESENT 1
    NWS Storm Prediction Center Norman OK
    0334 PM CST Tue Feb 18 2025

    Valid 182000Z - 191200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF
    SOUTHEAST TEXAS INTO SOUTHERN LOUISIANA...

    ...SUMMARY...
    Isolated severe thunderstorms remain possible this evening across
    parts of southeast Texas, shifting across southern Louisiana
    tonight. Hail should be the primary hazard, but a brief tornado and
    occasional severe gusts may occur along the immediate Louisiana
    Coast.

    ...20Z Update...
    The previous forecast remains on track. Low-level warm-air and
    moisture advection are already underway across coastal portions of
    TX and LA, as indicated by 19Z mesoanalysis. Current thinking is
    that the low-level warm-air/moisture advection will continue to
    increase and boost elevated CAPE to 1000 J/kg along the coast with
    the approach of a mid-level impulse currently situated over NM.
    Elevated thunderstorms should develop later this evening. Mainly
    hail is expected given elongated hodographs. However, if any
    supercellular structure can materialize along the southeast LA coast
    and become rooted in the boundary layer tonight, a damaging gust or
    tornado cannot be ruled out.

    ..Squitieri.. 02/18/2025

    .PREV DISCUSSION... /ISSUED 1029 AM CST Tue Feb 18 2025/

    ...Southeast Texas into Southern Louisiana...
    Water-vapor imagery this morning shows a shortwave trough moving
    into northern AZ from the Great Basin. This upper feature will move east-southeast during the period reaching northern LA/southern AR by
    daybreak Wednesday. Surface analysis this morning delineates an
    arctic cold front from the Concho Valley northeastward into north
    TX. This boundary will continue to surge south-southeastward to the
    TX coast tonight. A modifying airmass over the northwest Gulf Basin
    will aid in destabilization this afternoon/evening over southeast
    TX. Thunderstorms should eventually form by this evening across
    parts of southeast TX as large-scale ascent increases. Forecast
    soundings continue to indicate this thunderstorm activity will
    likely remain elevated with around 1000 J/kg MUCAPE. This activity
    will spread eastward across portions of southern LA late this
    evening and overnight while posing mainly an isolated hail threat.
    The surface-based thunderstorm probabilities are greatest near the south-central and southeast LA coast. However, low-level lapse
    rates in a deep/saturated environment will be modest, likely
    limiting tornado potential. Nonetheless, if a couple of storms can
    become near-surface based in the coastal parishes, a risk for severe
    gusts may accompany the stronger storms.

    $$

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Tue Jun 17 14:46:23 2025
    ACUS01 KWNS 171446
    SWODY1
    SPC AC 171444

    Day 1 Convective Outlook RESENT 1
    NWS Storm Prediction Center Norman OK
    0944 AM CDT Tue Jun 17 2025

    Valid 171300Z - 181200Z

    ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    KANSAS AND NORTHERN OKLAHOMA...

    ...SUMMARY...
    Severe thunderstorms producing numerous to widespread damaging
    winds, scattered large hail (isolated 2+ inches), and a few
    tornadoes are expected today across parts of the central/southern
    Plains and lower/mid Missouri Valley. The greatest threat for
    destructive gusts up to 70-100 mph is forecast across portions of
    Kansas and northern Oklahoma.

    ...Central/Southern Plains into the Lower/Mid Missouri Valley...
    A small but intense bow echo that moved south-southeastward across
    parts of KS overnight should continue to weaken this morning across
    northeast OK. But in the short term, an isolated threat for severe
    winds may continue until the cluster fully dissipates. Across
    eastern CO, occasional severe hail may occur with marginal
    supercells for another hour or two before additional weakening
    occurs. The net effect of this overnight/early morning convection on
    the severe potential across the southern/central Plains remains
    uncertain. But, a trailing outflow boundary from the decaying MCS
    now in northeast OK may prove instrumental in focusing significant
    severe potential this afternoon/evening.

    A subtle mid-level shortwave trough over the eastern Great Basin and
    central Rockies will continue to move eastward over the adjacent central/southern High Plains by this evening. At the surface,
    further deepening of a low over southeast CO is anticipated through
    the day, with this low forecast to develop into the TX Panhandle by
    early evening. A lee trough/dryline will extend southward from this
    low, while a convectively reinforced boundary should extend
    somewhere along/near the KS/OK border by mid to late afternoon, and
    potentially northeastward into eastern KS as well. The airmass
    across east-central CO into western KS was generally not
    convectively overturned yesterday into early this morning, with the
    12Z sounding from DDC still showing around 2800 J/kg of MUCAPE
    available.

    Convective development and evolution remain uncertain later today.
    Still, it appears likely that initially high-based thunderstorms
    will develop over the higher terrain of central CO this afternoon,
    and then spread east-southeastward over the adjacent High Plains
    through the evening. Much of eastern CO and vicinity will be in a
    post-frontal regime. But steep mid-level lapse rates and sufficient
    low-level moisture should support the development of moderate
    instability. Strong deep-layer shear should foster supercells
    initially, with associated threat for mainly large to isolated very
    large hail. Some upscale growth may eventually occur with this
    activity as it spreads into western KS this evening, along with an
    increased threat for severe/damaging winds.

    Farther east into central/eastern KS and MO, severe potential
    remains highly uncertain, with a myriad of possible solutions
    offered by various high-resolution guidance. In general, current
    expectations are for an increasing threat for numerous to
    potentially widespread severe/damaging winds across parts of KS into
    northern OK, with one or more intense clusters potentially
    developing in tandem with a strengthening low-level jet this evening
    across the southern/central Plains. Significant severe gusts of 75+
    mph remain possible, along with a few tornadoes with any sustained
    supercells along/near the boundary this evening as low-level shear
    strengthens. Overall, severe probabilities have been expanded
    southward some across the OK/TX Panhandles and northern/central OK,
    in an attempt to account for where the outflow boundary/front may be
    present this afternoon/evening. Additional adjustments to risk areas
    are likely with later outlook updates pending additional
    observational and model data.

    ...Mid-Atlantic into the Tennessee Valley/Southeast...
    Diurnal heating of a seasonally moist low-level airmass will occur
    today across the central Appalachians/southern Mid-Atlantic within a
    modestly sheared environment. Thunderstorms are expected to develop
    over higher terrain by early afternoon, and subsequently spread
    eastward through the evening. Some of this activity may form into
    loosely organized clusters. Occasional strong/damaging winds should
    be the main severe threat with this activity, particularly across
    parts of VA/MD where stronger instability is forecast.

    Farther south into the TN Valley/Southeast, a weak mid/upper-level
    trough with multiple embedded perturbations should advance slowly
    eastward through the day. Similar to yesterday, daytime heating of a
    moist airmass should foster moderate to locally strong instability
    this afternoon. Around 25-30 kt of mid-level southwesterly flow and
    similar values of deep-layer shear should support some loose
    convective organization with multiple thunderstorm clusters that can
    develop. Have expanded the Marginal Risk for isolated damaging winds southwestward to account for this potential.

    ..Gleason/Kerr.. 06/17/2025

    $$

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