Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sat Jul 22 2023 17:15:21

AWUS01 KWNH 221715
FFGMPD
FLZ000-GAZ000-ALZ000-MSZ000-222313-

Mesoscale Precipitation Discussion 0785
NWS Weather Prediction Center College Park MD
114 PM EDT Sat Jul 22 2023

Areas affected...Portions of the Southeast

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

Valid 221713Z - 222313Z

Summary...Thunderstorms this afternoon will be capable of
producing intense rain rates (1-2"/hr) and isolated 2-3" totals
are possible through the late afternoon. This may lead to
localized flash flooding.

Discussion...Along and ahead of a quasi-stationary frontal
boundary draped west to east across the region, lines of
thunderstorms have begun to grow upscale in a very warm and moist
environment. As of 17Z, dewpoints in the lower to middle 70s
combined with air temperatures well into the 80s and lower 90s has
yielded sufficient MLCAPE values of 2500+ J/kg. Precipitable water
values are also sufficiently high, analyzed to be between 2" and
2.25" per SPC mesoanalysis and the latest blended TPW product.
Shortwave energy rounding the base of the longwave trough over the
eastern U.S. combined with the moisture and instability has led to
the lines of deepening convection with recent IR imagery showing
rapidly cooling cloud tops.

Most recent CAMs are not handling the ongoing activity well,
particularly with the developing lines of storms across AL/GA,
either being several hours too late or displaced spatially
considerably. Regardless, the available moisture and instability
across the region and low level convergence along the front
suggests the ongoing storms will continue to grow upscale while
slowly advancing south/southeast with time. Additional storms are
likely to develop closer to the Gulf Coast along any sea/land
breeze interactions, similar to what the recent HRRR runs depict
between 19-23Z. The 12Z HREF neighborhood probabilities ramp up
considerably toward 22-23Z for 1" hourly totals with at least a
modest signal for localized/isolated 2" hourly totals. Through
23Z, localized 2-3" totals will be possible. Over the last 7 days,
precipitation has been much below normal in the outlook area, so
any excessive runoff/flooding concerns will most likely be more
isolated in nature and confined to urban locations and other
sensitive/vulnerable spots.

Taylor

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!6ZftFWnQ9g9ck8jNDFtteOoTOGA7-lkNfbVsIOdz5YTW63YRy7vEp8qjtbTXQIQoCnFS=
VeXWMlNwbFjceNbOr5thoWc$  for graphic product...

ATTN...WFO...FFC...JAX...LIX...MOB...TAE...

ATTN...RFC...LMRFC...SERFC...NWC...

LAT...LON   31838366 31348273 30648322 30358499 30388722=20
            30338846 30788882 31368798 31588545=20

=3D =3D =3D
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