238
AWUS01 KWNH 171727
FFGMPD
FLZ000-GAZ000-ALZ000-MSZ000-172325-

Mesoscale Precipitation Discussion 0282
NWS Weather Prediction Center College Park MD
126 PM EDT Fri May 17 2024

Areas affected...Southeast MS...Southern AL...Southwest GA

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

Valid 171725Z - 172325Z

SUMMARY...Concerns for heavy showers and thunderstorms training
over the same area will continue through this afternoon and toward
this evening across areas of southeast MS, southern AL and
gradually southwest GA. Additional instances of flash flooding
will be possible through this afternoon.

DISCUSSION...Satellite and radar imagery shows a broken band of
heavy showers and thunderstorms continuing to impact areas of
southeast MS, southern AL and a small portion of southwest GA. The
activity continues to be a bit elevated to the north of a warm
front advancing up across the Gulf Coast region.

A strong instability gradient is in place though along this front
with a notably moist and unstable airmass seen focusing up across
southeast LA and southwest AL that is characterized by MLCAPE
values of 2000 to 3000+ J/kg. This is also where there is a
convergent corridor of stronger south-southwest low-level flow in
off the northern Gulf of Mexico in the 925/850 mb layer that is
reaching 30 to 40 kts. The convergent nose of this continues to
advance up across southeast MS and especially southern AL where
some of the more organized and colder convective tops are noted.

PWs across southeast AL and the immediate offshore waters of the
northern Gulf of Mexico are very high for this time of the year.
In fact, the 12Z LIX RAOB depicted a 2.13" PW which is a record
high for the date. CIRA-ALPW data in the SFC-850 mb layer confirms
a very high concentration moisture that extends across large areas
of the northern Gulf of Mexico.

Given the continued interaction of the low-level jet with focused
moisture and instability transport into the aforementioned frontal
zone, the environment should remain conducive for additional areas
of heavy showers and thunderstorms with enhanced rainfall rate
potential. The 12Z HREF guidance and recent runs of the HRRR
suggest the most focused heavy rainfall threat for this afternoon
setting up over southern AL and gradually southwest GA.

Rainfall rates will be capable of reaching 2.5+ inches/hour, and
with additional cell-training concerns in vicinity of the front,
some rainfall totals by late this afternoon or early this evening
may reach 3 to 5 inches. The FFG values are a tad higher across
areas of southern AL/southwest GA away from the early-day
activity, so the flash flood threat in the short-term here is a
tad more conditioned on there being heavier totals. Regardless, at
least scattered instances of flash flooding will be possible.

Orrison

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

ATTN...WFO...BMX...FFC...JAN...MOB...TAE...

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

LAT...LON   32328626 32218448 31818343 31188353 30878418
            30958705 31108863 31508917 32058879 32298765