Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Tue Jun 20 2023 22:19:00

AWUS01 KWNH 202218
FFGMPD
MSZ000-LAZ000-210400-

Mesoscale Precipitation Discussion 0542
NWS Weather Prediction Center College Park MD
618 PM EDT Tue Jun 20 2023

Areas affected...Southern Louisiana

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

Valid 202220Z - 210400Z

SUMMARY...The flash flood threat continues in southern Louisiana
where additional training thunderstorms producing hourly rainfall
rates of 2-3"/hr are expected.

DISCUSSION...A cluster of training thunderstorms continues to
propagate west as an outflow boundary tracks west along the
Louisiana coast. A stalled frontal boundary also remains in the
area, acting as a trigger for storms north and west of Baton
Rouge. The environment remains primed to produce excessive
rainfall rates, sporting 2-2.25" PWATs and MLCAPE that is between
3,000-4,000J/kg. Area averaged HRRR soundings sampling the ongoing
thunderstorm activity around 00Z still shows as much as 40 knots
worth of sfc-6km vertical wind shear and over 100 m2/s2 of sfc-3km
SRH. Combined with the instability, moisture, and warm cloud layer
depths of 13,000', efficient warm rain processes will be common in
ongoing rounds of thunderstorms that may also contain organized
mesocyclones.

One factor helping to limit the flash flood threat in southern
Louisiana this evening are higher FFGs. Both 1-3hr FFGs are as
high as 4" in for many areas. That said, latest MRMS 3-hr QPE
shows areas southeast of New Orleans have measured as much as 4"
in some spots. This will remain the case into the early evening
hours with most of the latest CAMs in growing consensus that
storms should dissipate inside the 04-06Z window. Until then,
additional flash flooding is possible, particularly in low lying
areas and urbanized communities.

Mullinax

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!7fDp-VsLZjBSlD4sbEEhE60_i0KWhb1aR4hs0U1hQsTolT1-zq-F4XYSzuijOUEId3Fr=
IJb2iSzCUpKFhQBdnB6Liv4$  for graphic product...

ATTN...WFO...JAN...LCH...LIX...

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

LAT...LON   31349289 31109150 30719069 29899005 29348936=20
            28878938 29049014 29029063 29189135 29769235=20
            30449280=20

=3D =3D =3D
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