Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Tue May 13 2025 14:42:08

AWUS01 KWNH 131442
FFGMPD
PAZ000-MDZ000-VAZ000-WVZ000-131915-

Mesoscale Precipitation Discussion 0263
NWS Weather Prediction Center College Park MD
1041 AM EDT Tue May 13 2025

Areas affected...northern/western VA into WV/MD Panhandles

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

Valid 131439Z - 131915Z

SUMMARY...Localized flash flooding may develop across portions of
central to western VA into the central Appalachians through 19Z.
Periods of steady rain with embedded hourly rainfall of 0.5 to 1.0
inches (locally in excess of 1 inch) can be expected with
localized 3-hr totals of 2-3 inches.

DISCUSSION...1430Z GOES East water vapor imagery showed a slow
moving closed mid-level low centered over KY/TN with a negatively
tilted shortwave spoke rotating into NC. Flow aloft ahead of this
feature was becoming increasingly diffluent over the northern
Mid-Atlantic region with a jet streak noted on GOES East DMV (~70
kt) over south-central VA. Lower level winds were oriented from SE
to NW with 850 mb wind speeds of 25-45 kt (highest from southern
Chesapeake Bay into northwestern MD), a favorable orthogonal
orientation for upslope enhancement into the axis of the Blue
Ridge and central Appalachians.

While instability was limited, central VA into east-central WV was
positioned along the gradient in RAP forecast instability with
MLCAPE of 1000+ J/kg to the southwest developing early in the
afternoon. Favorable divergence and diffluece aloft will accompany
embedded mesoscale vortices within the broader stratiform
precipitation shield, likely help to enhance rainfall rates along
with periods of short term training. Factoring in upslope
enhancement due to terrain, periods of hourly rainfall between 0.5
and 1.0 inches will be likely at times late this morning into the
afternoon with localized hourly rainfall in excess of 1 inch
possible. The steady nature of the rainfall with occasional
enhancement to rainfall intensity is expected to support 2-3
inches of rain within a 3 hour period which may result in
localized areas of flash flooding.

Otto

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!4uz4ytRo_taTdQ6D8wyy1zgG3jcJLAIZeZb4rZ1BEX3kW6UAcbEayJQxl5kJsIbNSGer=
qzJsyssRhC034gj6sByQ0RI$  for graphic product...

ATTN...WFO...AKQ...CTP...LWX...PBZ...RLX...RNK...

ATTN...RFC...MARFC...OHRFC...NWC...

LAT...LON   40437845 39777762 38197733 37357806 37467920=20
            38257964 39447985 40227936=20

=3D =3D =3D
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