Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Tue Aug 08 2023 03:59:43

AWUS01 KWNH 080359
FFGMPD
NJZ000-PAZ000-DEZ000-MDZ000-VAZ000-DCZ000-080900-

Mesoscale Precipitation Discussion 0887
NWS Weather Prediction Center College Park MD
1158 PM EDT Mon Aug 07 2023

Areas affected...Central MId-Atlantic

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

Valid 080356Z - 080900Z

SUMMARY...Heavy rainfall of one inch in 30 minutes will shift
east-northeast from the DC metro and track near or south of
Interstate 95 to near Philadelphia overnight. Localized flash
flooding is possible.

DISCUSSION...A multi-cell cluster of heavy thunderstorms developed
within the past hour over the DC metro on a lingering axis of
moisture and instability. This is behind the main pre-frontal
convection from earlier this evening, but ahead of the cold front
which is over the central Appalachians. Rainfall rates of 1"/30min
has been estimated from KLWX.

A gradient of 500 to 2000 J/kg MUCAPE is noted in RAP mesoanalysis
extending east from DC where PWs are 1.9" to 2.1". Low level 25kt
SEly flow should enable this moisture and instability axis to lift
a bit north with 40kt ESEly mean layer flow directing activity
just south to near I-95 over the next few hours. Given the
sensitivity of the metro areas from DC to Philly this threat for
flash flooding is notable. This activity should track north of the
central/southern DelMarVa flooding rains this evening. FFG is
generally 2.5"+/hr over the northern DelMarVa and southern NJ, but
less than 2" for the I-95 urban centers.

The 00Z 3km NAMnest is the best recent HREF CAM to depict this
activity, though it's 04Z depiction is a bit north of reality,
which further favors a swath of heavy rain south of I-95 and north
of the earlier DelMarVA activity. Nonetheless, the available
moisture and instability poses at least a localized flash flood
threat through the rest of the overnight.

Jackson

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!8Rfvi7nt_LUdLPceU0PfbBHXIBuTrjOYCWIzdxAwnp2iB7levQQ2PoPHgwZK_cYa6jx3=
8LtfZkpiKiRGpKkyBe0IFfY$  for graphic product...

ATTN...WFO...LWX...PHI...

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

LAT...LON   40107509 40057470 39737412 39277452 38957508=20
            38687611 38767711 39377677 39557641 39967558=20
=20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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