850
AWUS01 KWNH 151604
FFGMPD
FLZ000-ALZ000-MSZ000-LAZ000-152200-

Mesoscale Precipitation Discussion 1014
NWS Weather Prediction Center College Park MD
1203 PM EDT Sun Sep 15 2024

Areas affected...north-central MS to southern MS/AL and western FL
Panhandle

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

Valid 151602Z - 152200Z

SUMMARY...Areas of training are expected to develop from the
central Gulf Coast into southwestern AL and central/eastern MS
through 22Z. Rainfall rates of 1 to 3 in/hr are likely, which may
result in localized areas of flash flooding.

DISCUSSION...At 1530Z, visible satellite imagery showed thick
cloud cover over much of central to northern MS while skies over
southern MS into the Mobile Bay region had only scattered clouds.
A low located in the 925-850 mb layer was identified over
south-central MS via area VAD wind plots with very slow movement
over the past few hours. Low level ESE winds of 20-30 kt were
present to the east of the low over eastern portions of MS into AL
while wind speeds dropped off to the west along the AR/MS border
down to Mobile Bay. A combination of speed and directional low
level convergence was supporting a broken axis of mostly warm
topped showers from northeastern MS down to the offshore waters of
MS/AL with increasing development noted across the
southern/clearer-sky regions. The environment was very moist with
area 12Z soundings indicating precipitable water values of 1.6 to
2.0 inches and wet bulb zero heights between 13-14 kft. SPC
mesoanalysis data from 15Z showed that MLCAPE of 500 to 1500 J/kg
was focused from the central MS/AL border, southward to the Gulf
Coast from central LA to the FL Panhandle, with higher values
toward the south.

Daytime heating is expected to expand the coverage of 500 to 1500
J/kg MLCAPE across the region but likely keeping the better
instability focused over southern areas where greater solar
insolation is expected. Scattered showers and thunderstorms will
likely increase through the afternoon with cell movement following
the general flow around the MS low. However, slow movement and
training will be possible with cells that form along the low level
convergence axis from north-central MS to the southern MS/AL
border, where lower topped cells will have a motion roughly
parallel to the axis of convergence.

Stronger low level convergence is expected from central to
northern MS where greater coverage of rain is expected but lower
instability may cap rain rates below 2 in/hr. Farther south,
rainfall rates may get as high as 3 in/hr due to the greater
instability combined with potential for slow movement but coverage
will likely be more isolated compared to up north. Portions of
this region have been anomalously wet over the past several days,
but other portions have missed out on the bulk of rainfall and are
nearer to average. At least localized flash flooding will be
possible through the afternoon.

Otto

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

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

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

LAT...LON   34089005 34078912 33328834 31958748 30698644
            30098675 29918785 29998896 30388928 31508959
            33139025