• Heavy Rain/Flooding AL/FL

    From Dumas Walker@21:1/175 to All on Thu Sep 12 08:45:00 2024
    AWUS01 KWNH 120926
    FFGMPD
    FLZ000-ALZ000-121525-

    Mesoscale Precipitation Discussion 0994
    NWS Weather Prediction Center College Park MD
    525 AM EDT Thu Sep 12 2024

    Areas affected...Southern AL...FL Panhandle

    Concerning...Heavy rainfall...Flash flooding likely

    Valid 120925Z - 121525Z

    SUMMARY...Strong bands of heavy showers and thunderstorms
    associated with weakening Tropical Storm Francine will impact
    areas of southern AL and especially the FL Panhandle this morning.
    High rainfall rates and localized training of storms will likely
    result in some areas of flash flooding.

    DISCUSSION...The latest GOES-E IR satellite imagery in conjunction
    with dual-pol radar shows a couple of stronger bands of heavy
    showers and thunderstorms tending to become better organized and
    focused across portions of the western FL Panhandle and the
    offshore waters of the Gulf of Mexico. This convection is
    associated with increasingly convergent and very moist low-level
    southerly flow while coinciding with an axis of moderately strong
    instability gradually shifting north in connection with a warm
    front slowly lifting up across the central and eastern Gulf Coast
    region.

    MLCAPE values of 1000 to 2000 J/kg are situated very close to the
    western FL Panhandle, and this instability coupled with PWs of 2.2
    to 2.4+ inches will be supporting extremely heavy rainfall rates
    with the stronger and more organized convective cells that
    materialize going through the morning hours. Overall, the
    low-level flow should become even more convergent over the next
    several hours and this coupled with proximity of the
    aforementioned front should favor plenty of forcing for multiple
    bands of strong convection.

    Rainfall rates may reach 2 to 3 inches/hour, and the latest HREF
    guidance and HRRR solutions suggest the FL Panhandle should be the
    focus for the heaviest rainfall totals with locally as much as 3
    to 5 inches of rain possible by late morning. However, the
    environment will be conducive for some of these rainbands to train
    over the same location, and it's not out of the question that
    locally heavier rainfall totals of 6+ inches could materialize.
    Heavy rains should also nose northward into parts of southern AL,
    but with this region a bit more detached from the axis of greatest
    instability, the rainfall totals here are likely to be somewhat
    lower.

    Some areas of flash flooding will be likely given the high
    rainfall rates and concerns for localized training of these bands
    of heavier showers and thunderstorms.

    Orrison

    ATTN...WFO...BMX...MOB...TAE...

    ATTN...RFC...SERFC...NWC...

    LAT...LON 31868716 31738601 31048516 30388476 29838478
    29768539 30138605 30218656 30208686 30298720
    30538741 31268757
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