• MESO: Heavy rain/flooding

    From Mike Powell@618:250/1 to All on Thu Apr 25 08:31:00 2024
    AWUS01 KWNH 250916
    FFGMPD
    MOZ000-ARZ000-OKZ000-KSZ000-251515-

    Mesoscale Precipitation Discussion 0168
    NWS Weather Prediction Center College Park MD
    515 AM EDT Thu Apr 25 2024

    Areas affected...Northeast OK...Southeast KS...Southwest
    MO...Northwest AR

    Concerning...Heavy rainfall...Flash flooding possible

    Valid 250915Z - 251515Z

    SUMMARY...Heavy showers and thunderstorms with some concerns for
    cell-training are expected to develop this morning. Some instances
    of flash flooding will be possible.

    DISCUSSION...Areas of showers and thunderstorms are expanding in
    coverage across portions of northeast OK and eastern KS as a
    gradually strengthening warm air advection pattern ensues across
    the central and southern Plains.

    A gradually moistening and strengthening low-level jet is
    overrunning a returning warm front draped generally northwest to
    southeast across the region, and this is yielding an increase in
    isentropic ascent which coupled with the arrival of a well-defined
    elevated instability axis is favoring the development and
    expansion of the convective activity. Another factor driving the
    increasing convective threat is a corridor of divergent flow aloft
    associated with the southeastward advance of an upper-level jet
    max over the lower OH Valley and corresponding RRQ jet dynamics.

    MUCAPE values are on the order of 1000 to 1500 J/Kg, but with a
    notable destabilization trend seen aloft over northern OK and
    southern KS where 3-hour MUCAPE differentials of +500 to +1000
    J/kg are currently seen. This elevated instability pool continues
    to advance off to the northeast as the low-level jet strengthens
    and transports increasingly moist air up from the southern Plains.

    This combined with the aforementioned forcing should favor an
    expansion of convection going through the early to mid-morning
    hours across northeast OK, eastern KS, and eventually into areas
    of southwest MO and northwest AR. Increasing PWs, reaching upwards
    of 1.5+ inches by 12Z, will work in tandem with the instability
    pool and moderately strong effective bulk shear to help drive
    rainfall rates that may reach 1.5 to 2 inches/hour with the
    stronger cells.

    The 00Z HREF guidance supports some of the convection becoming
    increasingly aligned in a northwest to southeast fashion, and this
    will favor cell-training concerns. Thus, a threat for locally
    enhanced rainfall totals will exist. Some storm totals of 3 to 4
    inches, with isolated heavier amounts, will be possible through
    mid-morning. In fact, a couple of HREF members suggest spotty 5+
    inch totals.

    While the antecedent conditions have been quite dry, the high
    rainfall rates and training concerns suggest that some instances
    of flash flooding will be possible.

    Orrison

    ATTN...WFO...EAX...ICT...LZK...SGF...TOP...TSA...

    ATTN...RFC...ABRFC...LMRFC...MBRFC...NWC...

    LAT...LON 38359536 38249419 37719302 36919226 35799196
    35009238 34819338 35009448 35649552 36709660
    37599674 38139631

    = = =
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