Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sun Aug 18 2024 22:46:36

AWUS01 KWNH 182246
FFGMPD
CTZ000-NYZ000-NJZ000-PAZ000-190444-

Mesoscale Precipitation Discussion 0901
NWS Weather Prediction Center College Park MD
645 PM EDT Sun Aug 18 2024

Areas affected...Northeast

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

Valid 182244Z - 190444Z

Summary...Widespread flash flooding continues this evening across
the Northeast, which will continue through the evening. Additional
considerable to locally catastrophic impacts cannot be ruled out,
especially over areas impacted by ongoing/earlier rainfall.

Discussion...Widespread thunderstorms are underway across the
Northeast ahead of a slow moving cold front analyzed across
central Pennsylvania and western New York. Over the last several
hours, rainfall rates upwards of 2"/hr combined with cell training
and repeating have have led to numerous reports of impactful flash
flooding across the region.

RAP proximity soundings in the vicinity of these cells highlight a
very favorable environment to drive intense rainfall rates upwards
of 2"/hr, including a nearly saturated profile with 1.8-1.9" PWAT,
1000-1500 J/kg MLCAPE (in a "tall-skinny" profile), and warm cloud
depths around 10,000 feet. While the mean-flow will support
relatively quick cell motions of 25-30 kts, the parallel
orientation to the synoptic forcing will favor training and
repeating with slow eastward progression.

As these storms continue over saturated soils and urban areas, the
threat of significant flash flooding will continue through this
evening, with 18Z HREF neighborhood probabilities showing a very
high (70-80%) chance of 3 HR FFG exceedence through 3z. Additional
considerable to locally catastrophic flash flooding impacts cannot
be ruled out going forward, especially over areas  hit hard from
ongoing/previous rainfall, including western Connecticut which as
seen 10+" of rainfall today.=20=20

Asherman

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!_EhPy_aASAHx-YNSUl2WYxCoJkaGxa2nRT0PCVZ3GJhhAwOJbkvPeg5kQdzFaDXX5S29=
zK6UDkOoZ7VFy_0H7x8OCno$  for graphic product...

ATTN...WFO...ALY...BGM...BOX...BUF...CTP...OKX...PHI...

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

LAT...LON   43487512 42147421 41917279 41077255 40227406=20
            40467555 41577625 43357623=20

=3D =3D =3D
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