Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Tue Jul 11 2023 21:22:58

AWUS01 KWNH 112122
FFGMPD
FLZ000-ALZ000-MSZ000-LAZ000-120221-

Mesoscale Precipitation Discussion 0701
NWS Weather Prediction Center College Park MD
522 PM EDT Tue Jul 11 2023

Areas affected...Central Gulf Coast

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

Valid 112121Z - 120221Z

Summary...Organized thunderstorms continue to shift southeast from
south-central MS to the central Gulf Coast and portions of
southeast LA this afternoon. There are ongoing scattered
thunderstorms near the coast, raising the risk of repeat rounds of
heavy rain containing rates of 2"+/hr which would support flash
flooding.

Discussion...Multi-cell thunderstorm clusters over south-central
MS at 21Z are shifting southeast ahead of a low pressure system
moving into southern AR. There is also diurnal convection with
multiple outflow boundaries ongoing along the MS/AL coasts into
the FL Panhandle which will persist and continue to expand over
the I-10 corridor of southeast LA. Heavy rain is noted in both
these areas with localized hourly rainfall estimates from regional
radars of 2" (3" northeast of Mobile 19Z-20Z).

The mesoscale environment for heavy rainfall continues across the
region with dewpoints in the mid to upper 70s, PW over 2", and
light mean layer flow resulting in slow storm motion.

A concern is for the multi-cell clusters to track over areas along
the coast that received heavy rain from the diurnal activity.
Also, upwind propagation vectors are from the NNE which raises the
risk of repeating heavy rain for southeast LA north of Lake
Pontchartrain. Some of these areas near the coast have also see
300 to 400% of normal precipitation over the last week, which
could exasperate flash flooding effects.

In the FL Panhandle, there is a notable Gulf breeze boundary
extending east from activity near Pensacola which may allow
development of cells that could train given the WNWly mean flow
which is nearly parallel to the boundary. PW does decrease farther
east over the Panhandle, limiting the flash flood risk farther
east.

Jackson

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!7X7xIl1AAkx7f1IO2-Qlo7uPaubB6Lao9BlxjTNnajpPZmXOJLZEM5wmg9r8oCGfRQD5=
isBJEOEQGumT1rseC3VS3Qw$  for graphic product...

ATTN...WFO...BMX...JAN...LIX...MOB...TAE...

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

LAT...LON   32348962 32238858 31908780 31418702 31038610=20
            30708526 30008549 30248707 30178781 30198895=20
            30399004 30909096 31159108 31529088 32119010=20
=20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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