Area Forecast Discussion
Issued by NWS Mobile, AL

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FXUS64 KMOB 252203

Area Forecast Discussion
National Weather Service Mobile AL
503 PM CDT Sun Oct 25 2020

.NEAR TERM UPDATE /Now Through Monday/...No major changes are
necessary for the prior forecast. Only a few notes to add given
trends the last few hours. A complicated low level stratus field
persists across southwestern Alabama and eastern MS, with a zone of
low-level subsidence evident progressing eastward into the area
based on visible satellite imagery. This should finally erode the
remaining low level stratus deck to at least allow for a few peeks
of sunshine before sunset tonight. Another oddity on visible
satellite is another wave-like area of subsidence that helped to
break the clouds across our eastern/central and now northern CWA as
its tracked from southeast to northwest, allowing for temps to rise
a bit more than expected to the upper 70`s and near 80. Other than
these quirks, the forecast remains on track for the remainder of
tonight through Monday.

Zonal flow has settled over the area as a weak upper level shortwave
trough has ejected to the northeast over the Mid- Atlantic
states. An upper level trough is located over the northern United
States with base tilted towards the southwestern United States. An
upper level ridge develops Monday over the eastern Gulf of
Mexico, promoting southwesterly flow aloft over the area through
the end of the period Monday evening.

A low level stratus deck has held much of the CWA in check this
morning into early afternoon with temperatures being held down in
the upper 60`s to lower 70`s. Where clouds have become more
scattered to broken, temps have managed to reach the middle 70`s.
Expect this cloud deck to continue to gradually erode this afternoon
and evening, with daytime temps only managing to rise about 3 to 5
degrees further prior to loss of daytime heating. As we head into
tonight, a similar scenario unfolds in relation to this past
night/morning as patchy fog and mist develop across the region.
Expect overnight lows tonight to be in the middle to upper 60`s near
the coast with upper 50`s and lower 60`s inland. On Monday, expect a
similar evolution to unfold with morning fog/stratus gradually
eroding, giving way to partly to mostly cloudy skies and highs in
the lower 80`s nearer the coast with middle 70`s inland. MM/25


.SHORT TERM /Monday night Through Wednesday night/...A dry
southwesterly flow pattern aloft will prevail across our forecast
area Monday night between an upper level ridge of high pressure
centered off the southeastern Atlantic coast and a deep upper
level trough spanning the southwestern CONUS. We currently expect
mostly clear to partly cloudy skies and dry conditions Monday
night. There could be some patchy fog late Monday night, mainly
over interior southeast MS and southwest AL, but confidence in
appreciable visibility reductions remained low enough to keep
mention out of the forecast for now.

The forecast through the remainder of the short term will focus on
potential impacts from tropical cyclone Zeta. This system is
forecast to strengthen to a hurricane as it approaches the Yucatan
peninsula Monday into Monday night. Zeta should emerge into the
southern Gulf as a minimal hurricane and gradually turn
northwestward and then northward across the Gulf Tuesday into
Wednesday. The timing of the turn and strength of the storm will
be driven by the strength of the ridging to our east and the
progression of the upper level trough/low pressure system and
associated timing of the cold front that will be ejecting across
the Plains through the early to middle part of the week. There
remains some spread in the ensemble GFS guidance on the eventual
track of Zeta, while the ECMWF ensembles have been more notably
further west. The official NHC track is more in line in the center
of the guidance, which would take Zeta toward the southern/
southeastern LA by early Wednesday afternoon, then northeastward
across MS/AL into Wednesday night. This scenario would keep
potential for a variety of impacts across our CWA, including
tropical storm force winds, storm surge, high surf/rip currents,
heavy rainfall, and perhaps a few tornadoes. The latest rainfall
forecast increased slightly, with 2-4" of rain with localized
amounts up to 6" possible (highest amounts currently favored in
southeast MS/southwest AL based on the current forecast track).
Surf heights look to build to 4-6 feet along our local beaches
Tuesday night, and potentially up to 6-9 feet and locally over 10
feet Wednesday afternoon and evening. A HIGH risk of rip currents
is expected Tuesday night into Wednesday (and also probably
Thursday and Thursday night). /21


.EXTENDED TERM /Thursday Through Sunday/...Zeta quickly lifts
northeast and becomes absorbed in the southwest flow aloft
Wednesday night. The upper level low to our west should move east
toward the TN Valley by Thursday. A narrow zone of ascent within
diffluence aloft should maintain a chance of showers and a few
thunderstorms into Thursday before things finally dry out
following frontal passage Thursday night. A dry zonal flow,
perhaps with some shortwave ridging aloft prevails Friday and
Friday night. Another trough could move our area this weekend,
possibly bringing a slight increase in cloud cover/moisture.
Isolated light showers could return this weekend, but confidence
in return moisture and sufficient lift is low enough to preclude
mention in the forecast at this time. Cooler temperatures return
late this week into this weekend. /21


.MARINE...Light offshore flow will transition to moderate easterly
flow into Tuesday as TS Zeta moves north over the southern Gulf of
Mexico. Winds and seas will increase through mid week as Zeta passes
west of area waters and moves onshore on the Louisiana coast. The
exact track of Zeta will have significant influence on marine waters
Wednesday and beyond. Flow remains moderate to strong onshore into
Thursday until a cold front moving over area waters brings a
moderate to strong west to northwest flow for the latter portions of
the week. MM/25


Mobile      60  82  66  83  70  80  66  78 /   0   0   0  60  60  80  60  40
Pensacola   65  83  71  83  73  82  72  80 /   0   0  10  60  50  80  70  50
Destin      68  83  71  82  74  81  74  80 /   0   0  10  50  50  70  60  50
Evergreen   61  83  64  83  70  81  69  79 /   0   0   0  40  40  70  70  50
Waynesboro  56  77  60  79  67  76  61  73 /   0   0   0  40  50  80  60  40
Camden      60  77  63  80  68  77  67  75 /   0   0   0  40  40  70  70  50
Crestview   63  84  67  82  70  79  71  80 /   0   0   0  50  40  70  60  50




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