Graphic for MPD #0028

Mesoscale Precipitation Discussion 0028
NWS Weather Prediction Center College Park MD
110 PM EST Wed Jan 24 2024

Areas affected...South-Central/Southeast LA...Central/Southern
MS...Western AL

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

Valid 241810Z - 250010Z

SUMMARY...An elongated axis of heavy showers and thunderstorms
with locally very heavy rainfall rates will continue to gradually
advance east this afternoon. Scattered to numerous areas of flash
flooding are expected from excessive rainfall totals, with some
locally significant urban flash flooding impacts possible.

DISCUSSION...A quasi-linear axis of heavy showers and
thunderstorms continues to gradually advance east across areas of
the Deep South, with the convection particularly robust right now
going across areas of south-central MS where very cold convective
cloud tops are noted. MRMS-driven rainfall rates over the last
couple of hours has been as high as 1.5" to 2.5"/hour in this
region.

Over the next several hours, an organized and occasionally broken
axis of convection is expected to focus across areas of
south-central to southeast LA northeastward up across central and
especially southern MS, and with the leading edge of this activity
expected to cross through western AL. 3-hour MLCAPE differentials
are +200 to +500 J/kg across southeast LA and southern MS out
ahead of the main convective line with MLCAPE values of 1000 to
1500 J/kg. This pooling of instability in conjunction with a 30 to
40 kt south-southwest low-level jet promoting rather strong
moisture convergence, and rather strong shear profiles, should
maintain organized convection with enhanced rainfall rate
potential.

Rainfall rates should continue to have the potential to be 1.5" to
2.5"/hour, and with PWs rising to locally over 1.75 inches and
some additional boundary layer destabilization possible, these
rates are likely to be attained. The latest hires CAMs favor a
setup that strongly supports cell-training, and while the area of
heaviest rains for the next 2 to 3 hours should be over areas of
central and southern MS, the environment down over south-central
to southeast LA will be notably conducive for training cells later
this afternoon. Facilitating this will be a stalling out of the
convectively driven outflow boundary which the guidance maintains
as a dominant focus for renewed convection.

Expect additional rainfall amounts generally from south-central to
southeast LA through central to southern MS to be on the order of
3 to 5 inches with isolated 6+ inch totals possible where any
cell-training occurs. Areas to the northeast into western AL will
get into heavier rains over the next several hours, but with
instability a bit more limited here, the rates will be a bit
lower, and thus the totals here this afternoon should be more into
the 2 to 4 inch range.

Areas of flash flooding are likely, and some locally significant
flash flooding impacts will be possible for some of the more
urbanized locations including New Orleans, Hattiesburg, and
Meridian.

Orrison

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

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

LAT...LON   34418771 34218706 33738685 33138697 32338743
            31438824 30458936 29379021 29099088 29329171
            29839197 30599161 31739082 32658997 33708874
           
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Last Updated: 110 PM EST Wed Jan 24 2024