• MESO: Mesoscale Discussion 0904

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Tue May 20 18:15:58 2025
    ACUS11 KWNS 201815
    SWOMCD
    SPC MCD 201814=20
    MSZ000-LAZ000-ARZ000-TXZ000-202015-

    Mesoscale Discussion 0904
    NWS Storm Prediction Center Norman OK
    0114 PM CDT Tue May 20 2025

    Areas affected...Eastern Texas into northern Louisiana

    Concerning...Severe potential...Watch possible=20

    Valid 201814Z - 202015Z

    Probability of Watch Issuance...40 percent

    SUMMARY...Thunderstorms developing along a cold front across eastern
    Texas will likely pose a severe threat through late afternoon
    downstream into northern Louisiana. Watch issuance is possible as
    storm coverage becomes more clear in the next couple of hours.

    DISCUSSION...A focused band of ascent is evident in recent GOES
    imagery across east TX along an eastward moving cold front. KSHV and
    KPOE have recently sampled a couple of deeper convective towers with
    echo tops reaching up to 15-20 kft, suggesting that the probability
    for deep convective initiation is steadily increasing. Further
    heating of a very moist environment ahead of the front over the next
    couple of hours will continue to erode inhibition and promote
    thunderstorm development by around 19-21 UTC. While eastern TX/LA is
    on the southern periphery of the stronger mid-level jet core to the
    north across AR, 40-50 knot mid-level flow atop weak low-level winds
    will still support elongated, nearly-straight hodographs. This thermodynamic/kinematic environment will support splitting
    supercells with an attendant risk for severe gusts and large to very
    large hail (possibly as high as 1.5 to 2.5 inches). Modest warm-air
    advection across northern LA is currently supporting sufficient
    low-level veering for around 100-150 m2/s2 0-1 km SRH, which could
    support some tornado risk. However, flow within this layer is
    expected to become more uni-directional through late afternoon, so
    it is unclear if storms will intensify and migrate into the
    favorably sheared environment before low-level helicity wanes.
    Additionally, displacement from the stronger broad-scale ascent to
    the north casts some uncertainty on convective coverage through the
    afternoon. Watch issuance will likely be needed if a sufficiently
    widespread threat becomes apparent.

    ..Moore/Hart.. 05/20/2025

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!8LZA1yJr_ftGtUrvK8bdgW-bcXnJqCYmrbNcikRrxzSlC9Blls9CmMUBmaN0rUqDLAMJb-0_d= F_uHQBUw02VZCFZzPg$ for graphic product...

    ATTN...WFO...JAN...LCH...SHV...HGX...

    LAT...LON 32179129 30899339 30619415 30579469 30759515 31119531
    31339529 31539514 32619381 32879347 33019312 33049221
    33019121 32739109 32459106 32179129=20

    MOST PROBABLE PEAK TORNADO INTENSITY...100-130 MPH
    MOST PROBABLE PEAK WIND GUST...55-70 MPH
    MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN


    =3D =3D =3D
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