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)