FXUS64 KMOB 211214 AAA

Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
614 AM CST Wed Feb 21 2018

.DISCUSSION...Updated for latest aviation discussion below.


12Z issuance...A light to moderate southeasterly wind flow will
continue to bring a very moist low level airmass into the area.
IFR/LIFR ceilings early this morning will gradually improve to
MVFR levels by late morning, with patchy fog dissipating as well.
Showers will develop throughout the day, with the best chance of
rain showers occurring between 18z to 22z, so kept the TEMPO
group in all the TAFs during this time frame. Southeast winds
between 10 to 15 knots will occur throughout the day, with
occasional higher gusts to around 20 knots possible. /22


.PREV DISCUSSION... /issued 446 AM CST Wed Feb 21 2018/

NEAR TERM /Now Through Wednesday night/...Another very warm day
with potential record setting high temperatures will occur again
today, this time across the entire forecast area. The forecast
high temperature for Mobile today is 80 degrees, and the record
high temperature is 79 degrees set in 2005. The forecast high
temperature for Pensacola today is 79 degrees, and the record high
temperature is 79 degrees set in 2005. The forecast high
temperature for Evergreen today is 82 degrees, and the record high
temperature is 81 degrees set just last year.

A strong surface high pressure ridge and upper level ridge over the
southeast states and eastern Gulf of Mexico will persist over the
next 24 hours. A light southerly to southeasterly wind flow will be
maintained across the region along the western periphery of the
surface high pressure ridge. Low level moisture below 850 mb will
also remain, with mainly mostly cloudy skies forecast through the
near term.

Isolated to scattered rain showers will develop throughout the day
across much of the forecast area due to boundary layer over-running
occurring on the backside of the surface high pressure ridge in
combination with decreasing stability from surface heating. The best
chance of rain will occur along and west of I-65, where widespread
rainfall amounts over the next 24 hours will range from 5 to 15
hundreds of an inch. 5 hundreds of an inch or less is expected east
of I-65. Isolated inland locations along and west of the Alabama
River could receive up to one-half inch of rain. Patchy fog early
this morning will dissipate by mid morning. /22

SHORT TERM /Thursday Through Friday night/...A surface ridge
remains parked over the western Atlantic and southeastern U.S.
through the short term, maintaining warm and moist onshore
surface winds across our area and keeping temperatures near or
above record levels. Aloft, the upper ridge to our east begins to
flatten and push south, orienting more southwest-northeast over
our area by midday Thursday. Subsidence beneath this ridge will
help to mitigate the development of showers and thunderstorms
Thursday and Friday across our area by effectively capping an
otherwise moist and unstable lower atmosphere. Rain chances
gradually return west of I-65 Friday night as the upper ridge
continues to push to our south and subsidence weakens over our
area. /49

LONG TERM /Saturday Through Tuesday/...A wet weekend and
possibly start to next week awaits us in the long term. Broad
upper-level troughing over the western CONUS pushes east across
the northern Great Plains heading into this weekend, with a
vigorous embedded shortwave rotating around the base of this
trough from the Desert Southwestern into the South Plains by late
Saturday. As this shortwave kicks east into the South Plains, rapid
cyclogenesis occurring in the lee of the southern Rockies spins
up a surface low over the South Plains near the TX/OK panhandles.
Caught in southwesterly deep-layer mean flow, this low moves
quickly northeast as it continues to deepen, reaching the Great
Lakes region by early Sunday. Meanwhile, an attendant cold front
associated with this low pushes southeast into the lower
Mississippi River Valley, eventually reaching our area late in the
day Sunday. The front then stalls offshore, leaving us with
cooler temps (back around seasonal) to start next week.

As was mentioned toward the end of the short term discussion
above, the upper ridge (and associated subsidence aloft) pushes
south of our area by late Friday, resulting in increasing rain
chances west of I-65 Friday night. With the ridge remaining to our
south, expect those rain chances to continue spreading across the
rest of our area Saturday as some showers (and perhaps a few
rumbles of thunder) develop in a moist and weakly-unstable
atmosphere. Rain chances then really ramp up Saturday night and
Sunday as the cold front approaches our area. While only limited
instability is expected (200-500 J/kg MLCAPE), we could get a few
thunderstorms mixed in ahead of the front. With sufficient
(albeit modest) deep-layer shear over our inland areas, a few of
these storms could briefly become strong to borderline severe,
though confidence in any widespread severe threat is low at this
time. Heading into early next week, warm and moist mid-level flow
overrunning the leftover dome of cool air at the surface supports
rain chances across our area through Tuesday. /49


FL...High Rip Current Risk through this afternoon for FLZ202-204-206.



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