Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Mon Dec 11 2023 01:17:22

AWUS01 KWNH 110117
FFGMPD
VAZ000-NCZ000-110516-

Mesoscale Precipitation Discussion 1196
NWS Weather Prediction Center College Park MD
816 PM EST Sun Dec 10 2023

Areas affected...central North Carolina into eastern Virginia

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

Valid 110116Z - 110516Z

Summary...Relatively narrow bands of convection are training over
localized areas and producing spots of 1+ inch/hr rain rates.=20
These rates could result in localized flash flooding - especially
in urbanized and/or low-lying areas.

Discussion...A robust warm conveyor remains entrenched across the
discussion area and extends from Florida to New England.  Within
that conveyor, areas of instability have sustained deeper,
embedded convective development that has exhibited organization,
occasional lightning, and training/repeating across localized
areas.  Recent radar mosaic imagery shows one of these bands
extending SSW-NNE from just north of Fayetteville, NC to just
south of Richmond, VA.  This band has been responsible for spots
of 1-1.5 inch/hr rain rates especially over the Raleigh, NC area
over the past couple hours.  Any translation off the current heavy
rain axis has been negligible during that timeframe, and with
upstream convective development across southern/central NC, along
with 1.4 inch PW values and ~500 J/kg MUCAPE all continue to
support efficient rainfall processes and locally heavy rain rates
in the short term.

Observations and models both suggest that the current regime will
persist for at least another 2-4 hours.  A vigorous shortwave
trough over Alabama is making steady eastward progress toward the
region while likely providing ascent for sustained convective
development.  This wave will eventually result in more forward
progress of heavy rainfall to the east - especially after around
04Z.  Until then, it is likely that narrow bands of heavy rainfall
will continue to pose a flash flood risk - especially where that
rainfall can occur across urban/low-lying areas.  Areal FFG
thresholds are generally in the 1.5-2.5 inch/hr range, again
further suggesting that any flash flood threat should remain
fairly isolated and localized.

Cook

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!41RHNmuCVZYY0Sb645c0N1LoZi6ZiOkbRzA_Zp8AhKpxph_ZYWWkCDuSDnOicIgiwqeR=
SW63KnYpw8kv4ZD_TwUKemU$  for graphic product...

ATTN...WFO...AKQ...MHX...RAH...RNK...

ATTN...RFC...MARFC...SERFC...NWC...

LAT...LON   38107726 37937643 36957627 36107690 35137829=20
            35467960 36157972 37257875=20

=3D =3D =3D
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