Mesoscale Precipitation Discussion 0146
NWS Weather Prediction Center College Park MD
1040 AM EDT Wed Apr 10 2024

Areas affected...Central/Eastern LA...Central/Southern
MS...Southwest AL...Far Western FL Panhandle

Concerning...Heavy rainfall...Flash flooding likely

Valid 101440Z - 102040Z

SUMMARY...Extremely heavy rainfall rates from organized areas of
showers and thunderstorms will maintain a significant threat for
flash flooding over the next several hours heading into the
afternoon. Areas of considerable to high-impact flash flooding are
expected along and near the I-10 corridor, including multiple
major metropolitan areas from New Orleans to Mobile.

DISCUSSION...The latest GOES-East IR satellite imagery in
conjunction with dual-pol radar continues to show a very
impressive cold-topped convective mass associated with strong QLCS
activity advancing east across the central Gulf Coast region. The
complex remains well-organized out ahead of a deepening area of
low pressure near the northwest Gulf Coast, and will continue to
advance off to the east over the next several hours while
promoting multiple hazards including severe weather and flash
flooding.

Radar imagery shows a well-defined MCV advancing through southwest
MS currently, and the energy/forcing associated with this
continues to help channel a strongly convergent and very moist
southerly low-level jet of 40 to 50+ kts up out of the northern
Gulf of Mexico and into large areas of eastern LA and southern MS.
Enhanced moisture and instability transport associated with this
is interacting with a west/east oriented stationary front draped
east across the region and ahead of the aforementioned deepening
low center.

MLCAPE values of 1000 to 2000 J/kg are focused currently along and
south of this boundary, with the greatest nose of instability
generally aimed into southeast LA including the New Orleans
metropolitan area. This coupled with enhanced vertical shear has
facilitated the development and expansion of numerous areas of
convection across eastern LA and far southern MS over the last 1
to 2 hours including some supercell activity which is all focused
out ahead of the main QLCS axis upstream.

PWs of 1.5 to 1.75+ inches are in place, and with the degree of
instability and shear focusing along the stationary front,
enhanced rainfall rates of 2" to 3"/hour will be likely as the
more organized convective cells evolve over the next several hours
off to the east.

The main concern over the next 3 to 6 hours will be the threat for
convection becoming aligned in a west-southwest to east-northeast
fashion across southeast LA through southern MS and gradually into
southern AL inclusive of the I-10 corridor. Enhanced training of
very heavy showers and thunderstorms is expected locally, and some
major metropolitan areas from New Orleans eastward to Mobile
should closely watch out for the threat of extremely heavy
rainfall rates and storm totals over the next several hours.

Areas farther north across central MS and west-central AL will
also become a focus for areas of heavy rainfall, but with
instability more limited here, the rates should be a bit lower.

An axis of 4 to 8 inches of rain cannot be ruled out across areas
of southeast LA through southern MS and into southwest AL by later
this afternoon. Lesser amounts of 2 to 4 inches are expected
farther north and generally north of the aforementioned stationary
boundary.

Flash flooding is likely across the region, and areas of
considerable to high-impact flash flooding are expected locally
and especially where the greatest areas of cell-training occurs.
This includes a notable threat to the I-10 corridor and the urban
corridors along it.

Orrison

ATTN...WFO...BMX...JAN...LCH...LIX...MOB...

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

LAT...LON   32768853 32488756 31748689 30558696 30058888
            29698952 29439041 29479138 29689197 29959212
            30959160 31559145 32069104 32608969