Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sun Mar 12 2023 10:00:30

AWUS01 KWNH 121000
FFGMPD
ALZ000-MSZ000-LAZ000-ARZ000-121500-

Mesoscale Precipitation Discussion 0100
NWS Weather Prediction Center College Park MD
559 AM EDT Sun Mar 12 2023

Areas affected...northern/east-central Louisiana, central/southern
Mississippi, southwestern Alabama

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

Valid 120958Z - 121500Z

Summary...A loosely organized complex of storms continues to pose
a risk of isolated, localized flash flooding through 15Z.

Discussion...Scattered storms have organized into a couple of
regimes - 1) a forward-propagating MCS across east-central
Mississippi, 2) trailing, mostly elevated convection from near
Jackson, MS to Monroe, LA, and 3) additional storms that initiated
along a cold front in far northeast Texas/northwest Louisiana.=20
The forward-propagating segment across east-central Mississippi
was producing rainfall rates generally in the 0.5-1.0 inch/hr
range mostly due to the quick movement of the line and lack of
convective training.  Areas upstream, however, were exhibiting 1-2
inch/hr rainfall rates (especially in northern Louisiana) due to
lack of forward propagation and orientation parallel to mean flow
aloft.  The storms are supported by a moderately buoyant (1000
J/kg MUCAPE), moist (1-1.5 inch PW) environment fostering the
ongoing heavy rainfall rates.  The storms were also moving toward
less-favorable ground conditions for widespread flash flooding,
with FFG thresholds generally above 2 inches/hr in most areas.

Over the next few hours, the greatest concern for flash flooding
is if training convection can materialize over sensitive and/or
urbanized areas.  Brief peaks of 2-3 inch/hr rain rates have been
observed throughout the evolution of convection since last night,
and these rates could approach FFG thresholds in spots as
convection gradually translates east-southeastward.  The overall
scenario supports an isolated flash flood risk continuing through
15Z or so as storms eventually reach the U.S. 84 corridor from
Natchez to Laurel, MS.

Cook

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!7PuEtJftfedgzFsBU-lKvOCpynXYLiJqSwfKsYaYfsle-fGjqduVAnFfFMwdf-ZBsTgV=
bd2qM-RZtJO4LobaiY1yuHc$  for graphic product...

ATTN...WFO...BMX...JAN...LIX...MOB...SHV...

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

LAT...LON   33089307 32919115 32928975 32908782 32608691=20
            31928689 31288757 31198993 31229154 31819267=20
            32179340 32729391=20

=3D =3D =3D
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