614
AWUS01 KWNH 250657
FFGMPD
VAZ000-NCZ000-WVZ000-TNZ000-KYZ000-251256-

Mesoscale Precipitation Discussion 1052
NWS Weather Prediction Center College Park MD
257 AM EDT Wed Sep 25 2024

Areas affected...eastern Kentucky, western Virginia, and
northeastern Tennessee

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

Valid 250656Z - 251256Z

Summary...Scattered showers and isolated thunderstorms continue to
migrate northeastward across the southern/central Appalachians,
where wet soils have left ground conditions vulnerable to
excessive runoff.  Isolated instances of flash flooding are
possible through early morning (12Z/8am Eastern).

Discussion...Ascent/difluence aloft associated with longwave
troughing across the central U.S. continues to support persistent,
but scattered thunderstorm activity across the discussion area.
The convection continues to persist in a marginally unstable
environment (~500 J/kg MLCAPE) although with sufficient moisture
(1.5 inch PW) for heavier rainfall to materialize in a few of the
cells.  Modest low-level forcing/focus was allowing for convective
bands to migrate northeastward amid appreciable steering flow
(around 35 knots), with localized backbuilding/training and
favorable orientation of the bands (to flow aloft) allowing for
prolonged rainfall and spots of 1 inch/hr rain rates at times.
FFG thresholds in the region were generally around an inch or
less, and convection was occasionally exceeding those thresholds,
suggesting isolated/sporadic flash flood potential in the short
term.

Models/observations suggest that the overall scenario supporting
isolated flash flood potential should remain in place through the
early morning hours (12Z or so).  Scattered convection should
continue to initially deepen across eastern Tennessee and migrate
northeastward atop areas of wet soils and hilly terrain, with
occasional and sporadic instances of flash flood guidance
exceedance.  Convective coverage and limited instability are
mitigating factors for a larger-scale flash flood threat, though a
few instances of flash flooding cannot be ruled out.

Cook

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

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

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

LAT...LON   37738248 37278166 37368085 37448034 37078013
            36528032 36108159 35858306 35648356 35728397
            36218439 36928407 37558355