• MESO: Mesoscale Discussion 1553

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Wed Aug 18 18:20:49 2021
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    ACUS11 KWNS 181820
    SPC MCD 181820=20

    Mesoscale Discussion 1553
    NWS Storm Prediction Center Norman OK
    0120 PM CDT Wed Aug 18 2021

    Areas affected...Northern Mississippi into northwest Alabama and
    southwest Tennessee

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

    Valid 181820Z - 182045Z

    Probability of Watch Issuance...5 percent

    SUMMARY...Scattered thunderstorms may produce sporadic damaging
    winds through the afternoon hours across parts of northern MS,
    northwest AL, and southern TN.

    DISCUSSION...A cluster of thunderstorms has shown signs of growth
    and intensification over the past hour in the form of increased
    lightning activity and cloud top cooling. While this activity is
    rather disorganized, the downstream environment is destabilizing as temperatures warm into the low 90s with dewpoints in the mid 70s.
    MLCAPE values have already increased to 1000-1500 J/kg and may
    increase further to near 2000 J/kg through the afternoon. Deep-layer
    shear is modest over the region and will limit storm organization,
    but amalgamating cold pools within the cluster and persistent ascent
    associated with a weak shortwave trough over the region will likely
    maintain thunderstorms into the early evening. Additional
    thunderstorm development is possible along a weak confluence axis
    noted in surface observations across the region. The combination of
    moderate MLCAPE and somewhat steep low-level lapse rates (near 7
    C/km) will support a damaging wind potential through the afternoon
    and early evening both with the developing cluster and with any
    stronger, more isolated cells. The overall severe potential is
    expected to remain sporadic, so a watch is not anticipated at this

    ..Moore/Dial.. 08/18/2021

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!rknSEOmPeZ4h9UdMkAcG8Jk0e4wISfRBj_4pj0KiDhPIkN_8rRWw3RiCWfr2TUNgykxQT3d7$=
    for graphic product...


    LAT...LON 34899025 35428941 35908828 35958707 35648645 35218622
    34478682 34028801 33828896 33728976 33779036 34089066

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