Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Fri Aug 25 2023 18:31:37

AWUS01 KWNH 251831
FFGMPD
VAZ000-WVZ000-OHZ000-KYZ000-252330-

Mesoscale Precipitation Discussion 0977
NWS Weather Prediction Center College Park MD
230 PM EDT Fri Aug 25 2023

Areas affected...eastern KY into southern WV and western VA

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

Valid 251829Z - 252330Z

SUMMARY...Areas of training heavy rain leading to flash flooding
is expected across portions of WV, and possibly developing into
portions of eastern KY and western VA. High rainfall rates of 1 to
2 inches in 30-60 minutes will be possible with the stronger cores.

DISCUSSION...A small cluster of thunderstorms continued to drop
southward in southwestern WV at 18Z, on the cool side of a remnant
outflow boundary that extended from western VA, through eastern KY
and southern OH. 18Z SPC mesoanalysis data indicated high MLCAPE
values on the warm side of the outflow boundary from southern OH
into eastern KY with 3000 to 4500+ J/kg. Precipitable water values
were hovering near 2 inches for the region west of the
Appalachians (ILN RAOB reported 2.03 inches from 12Z, possible
daily record), highly supportive of efficient rainfall with
earlier reports near Clendenin, WV showing over 1 inch of rain in
15 minutes.

Visible satellite imagery showed developing convection along
west-east cloud streets over portions of eastern KY, co-located
with an area of anomalous low level moisture transport within a
corridor of 15-25 kt 925-850 mb flow from the west, located south
of an advancing cold front. This region of moisture transport was
forcing overrunning the outflow boundary, supporting the ongoing
convection in southwestern WV.

Expectations are for the small thunderstorm cluster in
southwestern WV to continue advancing southward along the existing
instability gradient, supported by modestly diffluent flow in the
upper levels. In addition, thunderstorms are likely to increase in
coverage over eastern KY, eventually merging and possibly forming
a small cluster with potential for back-building and training.
Rainfall rates of 1-2 inches in 30-60 minutes are probable, posing
a likely and at least localized threat for flash flooding in the
sensitive terrain of the Appalachians and surrounding foothills.

Otto

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!71jnjqJLA3s5QiBo-cXEVqLeHYpEuxpuEhqJV59D2Y2dYxmPHAXDC5bSpTHT6wKxyD1i=
vPzz92c37Ku47noaJaaf7Rw$  for graphic product...

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

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

LAT...LON   38568237 38458180 38258145 37788128 37298147=20
            36998169 36808212 36678251 36658273 36718400=20
            36868440 37128461 37408469 37708459 38228418=20
            38478361 38558289=20

=3D =3D =3D
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