AWUS01 KWNH 280412
FFGMPD
FLZ000-ALZ000-MSZ000-281010-

Mesoscale Precipitation Discussion 1199
NWS Weather Prediction Center College Park MD
1111 PM EST Fri Dec 27 2024

Areas affected...Southern MS...Southwest AL...Far Western FL
Panhandle

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

Valid 280410Z - 281010Z

SUMMARY...Extremely heavy rainfall associated with training
showers and thunderstorms is expected over the next several hours
just north of the Gulf Coast involving portions of southern MS,
southwest AL and the far western FL Panhandle. Flash flooding is
already occurring locally and is expected to continue overnight,
including growing concerns for major urban flash flooding.

DISCUSSION...The latest GOES-E IR satellite imagery in conjunction
with dual pol radar shows a corridor of extremely heavy shower and
thunderstorm activity impacting portions of Harrison and Jackson
Counties in southern MS, along with Mobile and Baldwin Counties in
southwest AL. The convection over the last hour has been growing
further in organization with cooling convective tops (as low as
-65C) and the activity showing well-defined cell-training and
backbuilding characteristics.

This convection is being driving by moist, convergent and unstable
low-level flow advancing north in close proximity to a warm front.
This coupled with a focused axis of moisture convergence and
divergent flow aloft is likely to foster a continuation of locally
concentrated and slow-moving showers and thunderstorms with
cell-training concerns going well into the overnight hours.

MLCAPE values of near 1000 to 1500 J/kg have been pooling across
the central Gulf Coast region, and the 00Z RAOB from LIX along
with the latest CIRA-ALPW imagery shows a rather deep column of
moisture in place with PWs of 1.5 to 1.7 inches. This coupled with
as much as 30 to 40 kts of effective bulk shear, and the proximity
of the warm front should favor organized convection capable of
producing rainfall rates as high as 2 to 3 inches/hour with the
strongest cells.

A look at the 00Z HREF guidance suggests additional rainfall
totals going through dawn may reach as high as 4 to 8 inches, and
some localized totals approaching 10+ inches cannot be ruled out
given the enhanced backbuilding and cell-training concerns. Flash
flooding is already occurring, and there will be major urban flash
flooding concerns overnight along areas close to I-10. Areas near
and just to the north of a line from Biloxi, MS to Mobile, AL and
potentially edging east into the far western FL Panhandle north of
Pensacola will need to be very closely monitored overnight for a
threat for locally significant flash flooding.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!-Qif0ATdGfBHQYG_-1XDQqcfOslfa8rthM-HBDYZchRAaFAnAyLl9bPt88Te02ozUMxq=
1vdC7YvcR7BpPAdFtrREfTo$  for graphic product...

ATTN...WFO...LIX...MOB...

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

LAT...LON   31348709 31028674 30638688 30358737 30258835=20
            30378905 30668907 30958868 31278787=20

=3D =3D =3D
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