• Flood Risk Appalachians/SE US

    From Mike Powell@618:250/10 to All on Sat Oct 10 10:04:20 2026
    AWUS01 KWNH 101431
    FFGMPD
    NCZ000-SCZ000-GAZ000-102030-

    Mesoscale Precipitation Discussion 1470
    NWS Weather Prediction Center College Park MD
    1030 AM EDT Sat Oct 10 2026

    Areas affected...Portions of the Southern Appalachians and
    Interior Southeast

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

    Valid 101430Z - 102030Z

    SUMMARY...Flash flooding will continue to be possible through
    mid-afternoon as rainfall rates gradually increase with time.
    Short-term urban impacts may occur across north-central to
    northeast GA, with more terrain-focused impacts becoming a concern
    across upstate SC and southwest NC this afternoon.

    DISCUSSION...The latest GOES-E IR/WV suite shows a well-defined
    TROWAL axis pivoting across large areas of the Southeast U.S.
    around the eastern flank of what is now Post-T.C. Isaias. Deep
    layer moist east to southeast flow into the southern Appalachians
    and adjacent Piedmont areas of the Southeast will combine with a
    gradual uptick in instability with the diurnal heating cycle to
    promote a gradual increase in the coverage and intensity of shower
    and thunderstorm activity going through the mid-afternoon hours.
    This will be aided by divergent flow aloft downstream of the upper
    trough which coupled with upslope flow into the higher terrain
    should yield corridors of more focused lift.

    The latest RAP analysis does show some elevated instability up
    across areas of northeast GA up through southwest NC with as much
    as 250 to 500 J/kg of MUCAPE. This alone coupled with the
    orographics will support efficient and rather shallow-top
    convection, and especially with the available moisture in the low
    to mid-levels of the column. As boundary layer heating increases,
    slight deeper convection will become possible.

    Already radar shows some some linear convective structures across
    north-central GA that are lifting north-northeastward into the
    general vicinity of northeast GA, with some uptick in shower
    activity seen across upstate SC as well. The convective trends and
    latest hires model guidance suggests an uptick in rainfall rates
    in time, with potential for 1 to 2 inch/hour rainfall rates.

    Overall, the highest rates in the near-term should be across
    north-central to northeast GA, but by mid-afternoon and beyond,
    the rates up across upstate SC and southwest NC should increase.
    Generally as much as 2 to 4 inches of additional rain are expected
    for this MPD valid time period which is consistent with the latest
    multi-model hires consensus.

    Some urban flash flooding concerns will be possible in the
    near-term across north-central to northeast GA, but more
    terrain-focused impacts will gradually be possible this afternoon
    for upstate SC and southwest NC.

    Orrison

    ATTN...WFO...CAE...CHS...FFC...GSP...MRX...

    ATTN...RFC...ALR...ORN...NWC...

    LAT...LON 35998200 35828142 35448111 34988106 34628115
    34098147 33268159 32898201 32808279 32998332
    33578371 34488410 35088398 35518352 35888273
    $$
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    * Origin: capitolcityonline.net * KY, USA (618:250/10)