• MESO: Mesoscale Discussion 0657

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Mon May 17 23:26:12 2021
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    ACUS11 KWNS 172326
    SWOMCD
    SPC MCD 172325=20
    LAZ000-180030-

    Mesoscale Discussion 0657
    NWS Storm Prediction Center Norman OK
    0625 PM CDT Mon May 17 2021

    Areas affected...Southern Louisiana

    Concerning...Severe potential...Watch unlikely=20

    Valid 172325Z - 180030Z

    Probability of Watch Issuance...20 percent

    SUMMARY...Brief, weak tornadoes remain possible across southern LA
    this evening, though the duration of the threat remains uncertain.

    DISCUSSION...A broken QLCS associated with a gradually decaying MCV
    continues to move east/southeast across southern LA. Convective
    cells continue to develop along and ahead of this line, but have not
    acquired rotation as rapidly or for a long as prior convection
    earlier this afternoon. This may be related to gradually diminishing
    MLCAPE across the region (per RAP mesoanalysis trends) as well as a
    less favorable shear in the lowest 1-2 km across south-central LA as
    compared to southwest LA earlier today. Nonetheless, velocity data
    from KLCH continues to show transient rotation with cells developing
    along the line, and more persistent rotation associated with one or
    two cells just offshore. Curvature in the 0-2 km layer noted in KLIX
    VWP observations, along with nearly 1000 J/kg MLCAPE, suggests that
    the environment remains supportive of at least a low-end tornado
    threat for the next few hours. One or two additional brief, weak
    tornadoes are possible, but the potential for a more robust tornado
    threat appears low given gradual stabilization and the weakening
    trend of the MCV.

    ..Moore/Grams.. 05/17/2021

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!v9ifHF2n9pXx7D35mDFwgwO6LmxQCAOfW6ZkiERw03oMAERZtlK-foNJbhemBPi_iHynA1rE$=
    for graphic product...

    ATTN...WFO...LIX...LCH...

    LAT...LON 29609311 29969287 30309252 30649229 30529149 30419102
    30089059 29419048 29009063 28999089 29189126 29359260
    29609311=20



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