Area Forecast Discussion
Issued by NWS Mobile, AL

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FXUS64 KMOB 111228 AAA

Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
628 AM CST Sun Dec 11 2016

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


12Z issuance...Mostly VFR conditions through mid morning today
followed by VFR to MVFR cigs through midday then mostly MVFR cigs
through about 12.00z...followed by mostly IFR to LIFR cigs and
visibilities through 12.12z. Lower ceilings and visibilities late
today and tonight mainly in response to a weak sfc trough of low
pressure and better moisture near the surface moving northward
towards the coast. Winds will be northeast to east at 5 to 10 knots
through early this afternoon shifting southeast later this afternoon
continuing through 12.12z. 32/ee


.PREV DISCUSSION... /issued 504 AM CST Sun Dec 11 2016/

NEAR TERM /Now Through Sunday night/...In the mid to upper levels
expect mostly a zonal flow generally from west to east to continue
over the north central gulf states through tonight combined with a
weak inverted surface trough still lingering off the coast generally
stretching from the near the mouth of the Ms river to the central fl
panhandle by mid to late afternoon. Latest satellite loops continue
to show better lower moisture pooled in the vicinity of the trof
progged to lift northward today shifting inland mostly over the lower
half of the forecast this evening and overnight...combined with the
cooler near shore waters...resulting in the development of low
stratus and patchy fog over the near shore waters this evening
spreading inland late this evening through sunrise mon morning. Fog
may may become widespread mostly after midnight possible leading to
an advisory before the night is out early mon morning. Latest
satellite and short range model guidance also depict slightly better
forcing in the mid levels approaching from the the west today leading
to some light precip mostly in the vicinity of the weak boundary or
generally near and along the western florida panhandle coast
stretching onshore east of Pensacola. Better low to mid clouds will
also spread west and north through the course of the day especially
as sfc winds begin to veer to the south better late in the afternoon
continuing through the night.

With this pattern surface temps will begin to moderate today and
tonight along with sfc dewpts climbing to the mid 50s over much of
the lower half of the forecast area by midnight tonight. Highs today
will range from the lower to middle 60s to the east and along the
coast and the middle 60s to the west. Lows tonight will range from
the upper 50s to lower 60s near the immediate coast and the lower to
middle 50s for most inland areas to the north. 32/ee

SHORT TERM /Monday Through Tuesday night/...Zonal flow aloft will
prevail across the central Gulf coast region Monday and Monday night
on the base of a low amplitude upper trough encompassing much of the
east central CONUS. Surface high pressure will meanwhile continue to
shift southeastward across FL and the adjacent central Gulf of Mexico
Monday as a weak cold front positioned from southeast TX to the Lower
Mississippi and Tennessee Valley region Monday morning gradually
pushes southeastward and extends from southern portions of LA through
southeast MS and interior southwest and south central AL by late
Monday afternoon. The front should stall or perhaps retreat slightly
northward Monday night as weak surface low pressure lifts into MS. A
zone of increasing deep layer moisture and lift along and ahead of
the frontal boundary will bring an increasing chance of rain showers
primarily over interior areas of southeast MS and southwest AL Monday
and Monday night. Patchy early morning fog will remain possible
through the morning hours Monday, with additional patchy fog
development possible again late Monday night into early Tuesday
morning, especially near the coast. Mostly cloudy skies and
warm/humid conditions are otherwise expected Monday, with highs in
the lower to mid 70s. High surface dewpoints will keep overnight lows
Monday night much above normal in the upper 50s to lower 60s over
interior locations and in the mid 60s near the immediate coast.

Our forecast area will remain on the base of a broad longwave trough
Tuesday and Tuesday night, with a series of embedded shortwave
impulses expected to translate over the area within the
west/southwest mid level flow. The surface frontal boundary will
remain positioned from south central LA through interior portions of
MS/AL during the day Tuesday before slowly sagging south into our
forecast area Tuesday night. Short range model solutions are in
agreement that a zone of deep layer moisture and lift will continue
to spread over our forecast area Tuesday into Tuesday night,
contributing to a better chance of rainfall across the region
through the period. We have increased POPs to likely coverage over
interior areas during the day Tuesday, with a 40-50% chance of rain
closer to the coast. A few embedded thunderstorms will also be
possible with MLCAPE values increasing to 250-500 J/KG and 850 mb
lifted index values of 0 to -2 C. Additional showers will develop
along and ahead of the front Tuesday night. The NAM and ECMWF have
been signaling potential for some higher QPF/locally heavy rainfall
with some of the convection developing along the boundary over
southern and eastern portions of the area late Tuesday night, so have
increased forecast rainfall amounts slightly. POPs for Tuesday night
may also need to be adjusted upward with subsequent forecasts. Highs
Tuesday should range from the upper 60s to lower 70s, with lows
Tuesday night falling into the lower to mid 50s over northern and
western portions of the area behind the front and in the upper 50s to
mid 60s over the southern and eastern zones. /21

LONG TERM /Wednesday Through Saturday/...There will be a lingering
chance of light rain showers around the region Wednesday, with POPs
expected to decrease from west to east in the wake of the passing
frontal passage. Highs Wednesday will be cooler with readings ranging
from around 60 over our interior northwestern zones to around 70 near
the immediate coast. Clouds should gradually decrease Wednesday night
into Thursday with drier northwesterly mid level flow setting up over
the region. A strong surface ridge of high pressure will meanwhile
build from the Tennessee Valley to the Gulf coast region through
Thursday night. Expect cooler temperatures Wednesday night and
Thursday, with lows Wednesday night in the upper 30s to mid 40s
interior areas to around 50 near the coast, and highs Thursday
ranging in the 50s over most inland locations and around 60 to the
lower 60s coast. Lows Thursday night will be a little cooler - mid
30s to lower 40s interior and mid to upper 40s near the coast.
Surface high pressure moves east late in the period, with potential
for another front to approach the region sometime this weekend.
Confidence is low on the timing of this next front, but medium range
models are signaling potential for active weather with this feature
when it arrives. For now, we will have a low chance of rain showers
returning with increasing moisture Friday and Saturday, along with
moderating temperatures. /21

MARINE...A weak sfc trof positioned from the near the mouth of the
Ms river to the central Fl panhandle combined with a broad surface
ridge building south and west along the se coast will help generate a
light to moderate northeast flow early today shifting east then
southeast late today...then mostly south tonight and early mon
morning. Winds will continue to veer to the south southwest late mon
and mon night becoming mostly southwest on tue...then west to
northwest by late wed afternoon as a cold front moves across the
region. Northerly winds increasing 15 to 20 knots in the wake of the
front can be expected late in the week. With better moisture near and
along the trough low clouds and fog will be likely over the near
shore waters by this evening with some light rain also possible
generally from Pensacola stretching eastward. 32/ee




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