779
AWUS01 KWNH 311645
FFGMPD
MSZ000-LAZ000-312244-

Mesoscale Precipitation Discussion 0359
NWS Weather Prediction Center College Park MD
1245 PM EDT Fri May 31 2024

Areas affected...southern Louisiana, southern/coastal Mississippi

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

Valid 311644Z - 312244Z

Summary...Scattered, slow-moving convection will result in several
areas of 1.5-3 inch/hr rain rates at times through at least 22Z.
Flash flooding is possible in this regime.

Discussion...Over the past hour, the leading edge of a mature MCS
has crossed into southwestern Louisiana per radar mosaic imagery.
The MCS was making modest eastward progress (generally at around
35 knots or so) while producing spots of 1-2 inch/hr rain rates
(estimated per MRMS).  Additionally over the past hour, additional
convection has developed along and ahead of this MCS across much
of southern Louisiana.  That newer convection was drifting
northward while producing additional 1-2 inch/hr rain rates at
times.  The rain rates exhibited by this activity is supported by
a buoyant, moist airmass characterized by ~2000 J/kg MLCAPE and
1.5+ inch PW values, respectively.

Both cells and the leading edge of the MCS are likely to support
local/isolated areas of prolonged rain rates, with potential for 3
inch/hr rates at times.  Additionally, the presence of a low-level
boundary (subjectively analyzed along the I-10/12 corridor) will
likely aid in supporting MCS persistence across the southern half
of Louisiana today.

The rates are likely to fall in areas that have experienced
excessive rainfall over the past month.  With wet soils and
local/urban areas susceptible to runoff, at least a few instances
of flash flooding are expected today.  2-3 inch/hr FFG thresholds
should be approached on at least a spotty/isolated to scattered
basis.  The MCS will likely reach the Lafayette, LA area through
1830-1930Z and portions of the Baton Rouge/New Orleans Metro areas
after 20Z.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...JAN...LCH...LIX...MOB...SHV...

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

LAT...LON   31609011 30668910 29508893 28858946 29059190
            29649367 31089346 31469255