Area Forecast Discussion
Issued by NWS Mobile, AL

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FXUS64 KMOB 132057

Area Forecast Discussion
National Weather Service Mobile AL
357 PM CDT Tue Apr 13 2021

.NEAR TERM UPDATE /Now Through Wednesday/...A zonal upper flow
continues across the region today with surface ridging continuing to
move east of the area. Clouds have increased across the area from a
decaying complex of showers and thunderstorms to our west. Some
light rain from this may make into western portions of the area this
afternoon. This complex will continue to track southeast into the
Gulf and dissipate, however the clouds will likely linger across
much of the area this afternoon. Another complex of of showers and
storms will develop to our west tonight ahead of an approaching cold
front and overspread the region from the west through the morning
and into the afternoon hours. This is forecast to bring a quick
hitting 1-3" of rainfall in a short period of time. Due to the
already saturated ground conditions from previous heavy rains and
the potential of thunderstorms to "train" over the same areas, flash
flooding is a possibility. A Flash Flood Watch remains in effect
starting tonight for portions of southeast MS and SW AL.

Cloud cover and ongoing precip will hamper daytime instability, but
there may be enough deep layer shear and instability to support
storm organization on an isolated basis. For this reason, portions
of southeast MS and far SW Alabama are in a Marginal Risk for severe
thunderstorms on Wednesday. Locally damaging gusts and perhaps some
hail are possible Wednesday morning into the afternoon/early evening.

Lows tonight will range from the upper 50s and low 60s inland to mid
60s along the coast. Highs on Wednesday will be in the low to mid
70s northwest of I-65 to upper 70s and low 80s east of the
interstate. /13


.SHORT TERM /Wednesday night Through Friday night/...Zonal flow
persists over the region Wednesday night through Friday night. A
weak mid to upper level shortwave trough shifts east across the
gulf coast states overnight Wednesday into Thursday evening. At
the surface, a weak cold front gradually shifts southeast into the
area Thursday into Thursday night. In the wake of this, transient
high pressure pushes across the southeastern U.S. as another area
of low pressure develops over western Texas.

Our first bout of rainfall should be coming to an end during the
evening into overnight hours Wednesday, followed by another round
of rain and thunderstorms during the morning into early afternoon
hours Thursday. These two rounds may be accompanied by heavy
rainfall, and may pose a threat for localized flash flooding of
prone low lying and urban areas. This is particularly the case
over southwestern Alabama into southeastern Mississippi where a
flash flood watch is in effect through Thursday morning. There
will be a break in the rainfall on Thursday night before rain
chances begin to ramp up once again Friday with the aforementioned
front stalled across our area. Forecast models differ on placement
of the stalled front, and this will serve as a focus for better
rainfall chances.

Forecast temperatures are a bit uncertain during the period,
particularly later in the period into Friday. Lows Wednesday night
will be in the upper 50`s to lower 60`s for most locations, with
some middle 60`s across coastal counties of AL/FL. Highs Thursday
warm into the lower 70`s for most areas. Temperatures begin to
fall Thursday night into the upper 40`s inland to lower to middle
50`s elsewhere. Fridays high will contingent on cloud cover and
frontal placement, with the possibility of some spots only making
it into the lower to middle 60`s inland, and upper 60`s to lower
70`s closer to the coast. If the front stalls offshore, these
highs may end up being several degrees too warm. MM/25


.EXTENDED TERM /Saturday Through Tuesday/... Zonal flow aloft
gradually shifts over to southwesterly flow aloft by Monday as a
central Plains upper level trough digs into the southern Plains by
Tuesday. At the surface, another cold front is progged to move
across the region Saturday night into Sunday morning, with high
pressure dominating the central Plains states through Sunday. In
regards to the aforementioned trough, surface cyclogenesis may be
possible across the northern Gulf of Mexico Monday night. The
surface low would then likely track northeast up the eastern coast
of the U.S. Monday into Tuesday. Several chances for rain exists,
with the first being Saturday into Saturday evening as a mid-level
shortwave tracks across the central Plains into the Ohio Valley.
This will serve to generate scattered showers across the area.
Once this system has passed, our next rain maker will be from the
developing low offshore Sunday into Monday. Given timing
differences on this in the models have opted to maintain chance
PoPs in the grids Monday into Tuesday, although these could be
adjusted upwards with time. Temperatures Saturday recover some,
with temperatures climbing into the lower to middle 70`s.
Temperatures fall Saturday night into the lower to middle 50`s for
most locations, upper 50`s across the FL panhandle. Temperatures
Sunday, Monday, and Tuesday should top out in the lower 70`s for
most locations, with lows Sunday night and Monday night featuring
upper 40`s over interior southeastern MS and southwestern AL and
lower to middle 50`s elsewhere. MM/25


.MARINE...Southerly flow continues through tomorrow ahead of an
approaching cold front. Offshore flow is expected to return late
Wednesday night into Thursday following the passage of a cold front.
Little change in seas is expected through this week, except near
thunderstorms from late tonight through Thursday. /13


AL...Flash Flood Watch from late tonight through Thursday morning for

MS...Flash Flood Watch from late tonight through Thursday morning for

GM...Flash Flood Watch from late tonight through Thursday morning for



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