747
AWUS01 KWNH 232104
FFGMPD
VAZ000-NCZ000-WVZ000-TNZ000-KYZ000-240215-

Mesoscale Precipitation Discussion 1044
NWS Weather Prediction Center College Park MD
504 PM EDT Mon Sep 23 2024

Areas affected...eastern KY/TN into the central/southern
Appalachians

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

Valid 232103Z - 240215Z

Summary...Isolated flash flooding will be possible across portions
of eastern KY/TN into the central/southern Appalachians. Rainfall
rates of 1-2 in/hr will be possible where brief training of cells
occurs.

Discussion...2045Z visible satellite and regional radar imagery
showed scattered thunderstorms ongoing from portions of central
KY/northern TN into the central/southern Appalachians. A recent
increase in the coverage of storms appears to be driven by daytime
heating and increased ascent ahead of an elongated vorticity
maximum observed on water vapor imagery from western TN into
northern MS. SPC mesoanalysis data from 20Z showed 1000-2000 J/kg
MLCAPE and weakly anomalous precipitable water values of 1.5 to
1.9 inches across the region. The ongoing cells were moving with
the deeper layer mean wind of 15-25 kt in a general eastward
fashion.

There is some concern that as the vorticity max over TN/MS
continues to advance toward the northeast, increased forcing ahead
of this feature will act on instability already in place to
support greater coverage of cells heading through the remainder of
the evening, increasing the potential for areas of brief training
that could support locally higher rainfall rates of 1-2 in/hr.
While this threat is expected to remain low, areas of low FFG
exist ever portions of eastern KY/TN into the Appalachians with 1
to 2 inches in an hour.

Outside of terrain, no significant boundaries were analyzed that
are expected to have an impact on cell placement and the
expectation moving forward is that cells will continue to remain
somewhat disorganized and multicellular in nature, although
increasing shear from the west may support some more organized
cells. However, beyond ~02Z, the expectation is that diminishing
instability with the loss of daytime heating will contribute to a
reduction in storm coverage and a lowering of the flash flood
threat.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...GSP...JKL...LMK...MRX...RLX...RNK...

ATTN...RFC...LMRFC...OHRFC...SERFC...NWC...

LAT...LON   37758313 37678264 37428100 37278083 36548088
            36148161 35238255 35358389 35848446 36568457
            37018485 37318493 37658490 37738455 37748401