River Flood Warning 51, NWS Mobile, AL

Area Forecast Discussion
National Weather Service Mobile AL
644 AM CDT Wed Aug 24 2022

.AVIATION...
12Z issuance...General VFR conditions were noted across the
forecast area at 11z, except for LIFR/IFR CIGS over inland
southeast Mississippi and west. With southerly low level winds
indicated on area model and physical soundings, this low stratus
deck is expected to continue to spread north. Areas along the
coast may see drops in CIGS to low end MVFR levels as isolated
rain showers over the northern Gulf move inland. Am also expecting
the coverage of showers and thunderstorms to increase today, with
impacts to operations likely as conditions drop into low end
MVFR/IFR levels possible. This activity will decrease tonight,
but is expected to continue into the overnight hours. Light
northerly winds are expected to rise to 5 to 10 knots today,
shifting to easterly in the process. Winds will lighten overnight.
/16

&&

.PREV DISCUSSION... /issued Issued by National Weather Service New Orleans LA/

NEAR TERM...Big concern today is potential for heavy rain. Almost
the entire CWA is under a Slight Risk for excessive rainfall with
a Moderate Risk just to the northwest across east-central MS. A
low level jet is forecast to develop over southern MS and portions
of southeast LA. This would nose into west-central AL and
portions of southeast and east-central MS providing rather strong
low level convergence. At the same time the northern stream Jet
will be rounding the base of the trough across the AR/LA border and
then back to the east-northeast over AL, GA, eastern TN, and the
Carolina's. This will lead to very impressive upper level
diffluence, especially over areas along and west of the AL/MS
border. Moisture will be Grade A prime over the area today. LIX
sounding last night, although likely a little contaminated
measured a PW of 2.48" but even GOES16 TPW was measuring around
2.39" across southwestern MS and northeast LA late last night.
Conditionally unstable to even moderate instability will be in
place leading to thunderstorms and not just showers and a few
embedded thunderstorms. Warm mid level temps also in place will
continue to lead to warm rain processes and with the other
features in place heavy rain is likely especially near the nose of
that weak low level jet. Due to that and the Moderate Risk for
excessive rainfall we have issued a Flood Watch for Perry, Greene,
and Choctaw counties until this evening. It may need to be
extended but we will let the daytime make that decision after
seeing what occurs today. /CAB/

SHORT TERM...Thursday and Friday we will continue to be in this
wet pattern. The trough over the region on Wednesday will still
be over the area continuing to provide support to allow for a few
more days of numerous to widespread convection. The slight change
is that the trough axis will slowly be working east and could move
east of the CWA overnight Thursday and that may help to push some
of the heavier rain to the east on Friday. However, that will not
be the case for Thursday. The trough axis will be directly over
the north-central Gulf. In the low levels there are indications of
a weak low level jet or at least better low level convergence
will set up across southeastern MS and along the AL/MS border.
Aloft we will be under the RRQ of a rather decent jet for this
time of the year. This will provide very favorable divergence
aloft and that will enhance the rainfall potential. Combine that
with the low level convergence, deep moisture (PWs of around
2.25"), low level moisture continuing to pump in from the Gulf,
mid level temps of
-5 to -6 C, and we have the ingredients still in place for
efficient warm rain process.

As for Friday, again that trough axis may be over the eastern
fringes of the CWA and slightly drier air under weak northerly
flow looks like it will be pushing in. This should really lead to
a reduction in coverage of storms but it will still be a wet day
for most if not all of the area. /CAB/

LONG TERM...Heading into the weekend and next week we should see
a slight break in the rain but rain chances will start to increase
again next week. On Saturday short wave ridging will take place
over the Lower MS Valley and it will continue to slowly slide
east across the southeastern CONUS Saturday night and Sunday. The
s/w ridging should increase the subsidence a little but with
tropical moisture still in place and light winds, seabreeze
activity should easily develop Saturday and then slowly drift
north. On Sunday the  ridge may be far enough east while at the
same time another short wave will be moving across the Upper and
Mid MS Valley and likely put the region back under southwest flow.
/CAB/

MARINE...High pressure will remain in control across the
northeastern Gulf and southeastern US. It will remain centered
northwest of the coastal waters and this will maintain a light
easterly to southeasterly wind. Seas will also be rather benign
and likely below 3 feet. Locally higher winds and seas are
expected with thunderstorms and a few waterspouts will be possible
if not likely. /CAB/

AVIATION...06Z issuance...Mostly MVFR to VFR conditions across
the area as light to occasionally moderate rain moves east of
I-65 and eventually east of the area over the next few hours. Some
IFR ceilings will likely develop across southeastern Mississippi
and into interior southwestern Alabama overnight and obs across
Mississippi show this area of lower stratus has already begun to
settle in. Winds will be light out of the east to southeast
throughout the period. By the morning, showers and storms will
quickly develop across the area and overspread with MVFR ceilings
and visbys. Some temporary reductions in visbys and ceilings will
be possible during the mid-afternoon as some heavier thunderstorms
will be possible. BB/03

&&

.MOB WATCHES/WARNINGS/ADVISORIES...
AL...None.
FL...None.
MS...None.
GM...None.
&&

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