• MESO: Mesoscale Discussion 0167

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Thu Feb 16 20:20:42 2023
    ACUS11 KWNS 162020
    SWOMCD
    SPC MCD 162020=20
    ALZ000-MSZ000-162115-

    Mesoscale Discussion 0167
    NWS Storm Prediction Center Norman OK
    0220 PM CST Thu Feb 16 2023

    Areas affected...portions of south-central and southeastern
    Mississippi...into western Alabama

    Concerning...Tornado Watch 38...40...

    Valid 162020Z - 162115Z

    The severe weather threat for Tornado Watch 38, 40 continues.

    SUMMARY...The tornado threat continues and may intensify over the
    next 1-2 hours across portions of southern MS into western AL.

    DISCUSSION...As of 2015 UTC, hi-res radar imagery showed a loose
    cluster of supercells becoming better organized across Jasper,
    Jefferson Davis, Marion and Walthal counties, MS. Area VADs have
    shown consistently strong low-level wind profiles with 0-1km bulk
    shear around 25-30 kt. As these supercells have matured, low-level
    mesocyclones have trended stronger, suggesting tornado potential is
    increasing. This is further corroborated by a recent report of a
    tornado in Smith County, MS. A corridor of enhanced tornado
    potential may evolve over the next hour or two as supercells
    continue to track northeastward and reach maturity within the
    strongly sheared airmass.

    ..Lyons.. 02/16/2023

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!_5r2t_0WiKWsZHMOsqZweAnSZ31uYvdeKxgjXKYyCx4d5iT-l8n7bLBcquQzRWTOCp7p4vjJP= 2XTgJhQU-SA6WqA2Y0$ for graphic product...

    ATTN...WFO...BMX...MOB...JAN...LIX...

    LAT...LON 31159064 32068946 32558868 32718809 32328780 31238834
    31128862 31078927 31049033 31159064=20


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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Wed Feb 28 01:47:36 2024
    ACUS11 KWNS 280147
    SWOMCD
    SPC MCD 280146=20
    KYZ000-OHZ000-INZ000-ILZ000-MOZ000-280345-

    Mesoscale Discussion 0167
    NWS Storm Prediction Center Norman OK
    0746 PM CST Tue Feb 27 2024

    Areas affected...southern Illinois and Indiana into portions of
    northern Kentucky and southwest Ohio

    Concerning...Severe potential...Watch likely=20

    Valid 280146Z - 280345Z

    Probability of Watch Issuance...95 percent

    SUMMARY...The severe risk is expected to increase this evening and
    overnight upper-level ascent and a fast-moving cold front intersect
    with the retreating dryline. Bowing segments and supercells will be
    capable of all severe hazards as they spread east along the OH
    Valley. A new Tornado Watch will likely be needed in the next 1-2
    hours.

    DISCUSSION...Over the last hour, surface obs near STL showed the
    dryline retreating westward with a surge in dewpoints to the low 60s
    F. Evening water-vapor and IR imagery showed large-scale ascent
    beginning to impinge on the warm sector across portions of the mid
    MS and lower OH Valleys. Weak convection in the well-mixed warm
    sector to the west has steadily deepened, and should move into more
    robust surface moisture this evening. Additional convection also
    appears likely to develop along the cold front surging southeastward
    across eastern MO later tonight.

    Low 60s F surface dewpoints and ~1000 J/kg of MLCAPE will support
    strong updrafts within the warm sector. Very favorable deep-layer
    shear (50-60 kt) will support a mix of supercells and short bowing
    segments. Damaging gusts and hail appear likely, given the strong
    vertical shear and favorable buoyancy. Rapidly increasing low-level
    shear (evident on area VADs) may support a risk for tornadoes,
    especially with more sustained supercells. A significant tornado
    also cannot be ruled out, given very large effective helicity of
    400-600 m2/s2 and a 50-60 kt 850 mb jet.

    Confidence remains low on the exact timing of convective initiation,
    given that some convective inhibition remains. As ascent begins to
    deepen, most hi-res guidance, and extrapolation of weaker convection
    farther west, suggests new storms should develop in the next 1-2
    hours and quickly become severe. With all severe hazards possible, a
    new Tornado Watch is likely needed in the next couple of hours for
    parts of southern IL/ IN into northern KY and southwestern OH.

    ..Lyons/Edwards.. 02/28/2024

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!_xLmU10zU3pAhfeFcfzrSKCdZkCqKI5zRZcuQQZhRVqIzSO7N0p_p7XRG-reVYSnKabFVvowm= HZglNu0-Dy4tMvLlrw$ for graphic product...

    ATTN...WFO...ILN...LMK...IND...PAH...ILX...LSX...

    LAT...LON 36848841 36748893 36778938 37198983 37468988 37978985
    38718946 39188830 40018593 40278485 40188455 39788434
    39268422 38748426 38288439 37958475 37428636 36888832
    36848841=20


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