Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Mon May 15 2023 17:52:03

AWUS01 KWNH 151752
FFGMPD
TXZ000-152350-

Mesoscale Precipitation Discussion 0301
NWS Weather Prediction Center College Park MD
151 PM EDT Mon May 15 2023

Areas affected...Central Texas/Hill Country into the Big Bend

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

Valid 151750Z - 152350Z

Summary...Localized rainfall rates of 1-2"/hr may drive a isolated
flash flood threat through the afternoon.

Discussion...Disorganized areas of convection are beginning to
converge in the vicinity of Central Texas (aka the Hill Country)
early this afternoon. The mesoscale environment is characterized
by surface-based CAPE of 1000-2500 J/kg, precipitable water values
of 1.2-1.5 inches (near the 90th percentile, per DRT sounding
climatology), and effective bulk shear near 10 kts. Given the lack
of shear and overall upper dynamics, storms are expected to remain
rather disorganized with cell mergers and some localized repeating
of more intense rainfall rates (1-2"/hr) driving an isolated flash
flood risk. Most concerningly, antecedent conditions are rather
wet with flash flood guidance (FFGs) generally 1.5-2.0" over 1-hr,
and 2.0-2.5" over 3-hr. Given the favorable environment for heavy
rainfall (with converging cells ahead of a slow moving cold
front), localized instances of flash flooding are considered
possible through late afternoon.

In addition, included a portion of the Texas Big Bend where an MCV
in northern Mexico is pivoting towards this afternoon. While the
tropospheric column is a little less moist here (precipitable
water values 1.0-1.2 inches) and FFGs are a little higher
(2.0-3.0" over 3-hr), an isolated instance of flash flooding will
be possible here as well.

Churchill

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!_twHqoKG8yOjnus707gLhBFy2-KvxWj5zJOVI7vjR7UItrzCSvFeXO3Zwn-fCrs18izO=
dXoqZ0jEX-idtvLYQp9Gxbo$  for graphic product...

ATTN...WFO...EWX...FWD...MAF...SJT...

ATTN...RFC...WGRFC...NWC...

LAT...LON   31549944 31389841 30379784 29699869 28700045=20
            28940110 29150160 29240238 28910290 28920349=20
            29320410 29990395 29940223 30360115=20

=3D =3D =3D
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