Area Forecast Discussion
Issued by NWS Mobile, AL

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FXUS64 KMOB 101312 AAA

Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
712 AM CST Sat Dec 10 2016

.DISCUSSION...See updated information for land and marine areas below.


.UPDATE...The freeze warning for the coastal areas of alabama and
northwest florida has expired. 32/ee


.MARINE...The small craft advisory has expired for the gulf waters
of alabama and northwest florida out to 60 nm. Small craft should
exercise caution in these areas this morning. 32/ee


.PREV DISCUSSION... /issued 610 AM CST Sat Dec 10 2016/

DISCUSSION...Updated for latest aviation discussion below.

12Z issuance...VFR conditions through 11.12z. Winds will be
northeast at 5 to 8 knots with higher gusts through early this
afternoon...gradually shifting east this evening and overnight.

PREV DISCUSSION... /issued 451 AM CST Sat Dec 10 2016/

NEAR TERM /Now Through Saturday night/...In the mid to upper levels
expect mostly a zonal flow...generally from west to
continue across much of the deep south and north central gulf states
through 12z sun. At the surface a strong surface ridge of high
pressure centered mostly over the TN/OH river valleys early this
morning will shift east to the mid Atlantic coast through 12z sun.
With this pattern the colder/drier air that pushed well to the south
over the region will begin to slowly moderate later today and
tonight. Model guidance also continues to show a gradually increase
in 1000 to 500 mb thickness levels through early tonight with a
better increase generally from the west to east beginning early sun
morning...supporting a slow trend throughout this afternoon and early
tonight. By late tonight and early sun morning better moisture in the
mid to upper levels is also noted moving in from the east beginning
late tonight and early sun morning possibly leading to more clouds
than sun over extreme eastern and coastal sections of the forecast
area early sun morning. As for temps with the slow warming trend
mentioned above highs today will continue to run around 5 degrees
below seasonal averages...climbing to the mid 50s for most areas
with the exception of the lower 50s over extreme northern sections of
the forecast area. This pattern will also reflect overnight and early
sun with lows still running 5 to 7 degrees below average ranging from
the upper 20s to lower 30s for most of the northern half of the
forecast area and the middle 30s to lower 40s further south generally
along and south of the I-10 corridor. 32/ee

SHORT TERM /Sunday Through Monday night/...A zonal flow pattern
aloft will prevail across the central Gulf Coast region Sunday, while
a surface ridge of high pressure continues to extend from the Western
Atlantic/Eastern Seaboard through the southeastern U.S. A dry deep
layer airmass will remain in place across our forecast area Sunday,
with precipitable water values generally averaging between 0.6" and
0.9" around the region. A dry forecast will therefore continue
across just about all of the area Sunday. The exception will be near
the northwest FL panhandle coast, where short range models do show
weak isentropic ascent potentially aiding in the development of
isolated rain showers Sunday afternoon as low level flow gradually
turns from easterly to southeasterly through the day. We will keep a
20% chance of rain in the forecast south of a Pensacola-Destin line
Sunday afternoon. Low level moist advection will otherwise bring
increasing surface dewpoints/higher afternoon relative humidity to
the area through Sunday afternoon. A shortwave trough will move
across the Mid-Mississippi and Tennessee Valley region Sunday night,
while an associated frontal boundary subsequently approaches north
central LA, northern MS, and the Tennessee/Ohio Valley vicinity. A
zone of deep layer moisture and lift along the frontal axis will
bring an increasing chance of rain showers, primarily to the
northwest and north of our CWA late Sunday night. We trended POPs
downward a bit from the previous forecast, but will still retain a
slight chance of rain as weak isentropic lift could contribute to at
least isolated shower development around the region. Highs Sunday
afternoon will be in the mid to upper 60s. Lows Sunday night should
trend much warmer in the lower to mid 50s interior, and upper 50s to
lower 60s near the coast.

The surface frontal boundary will slowly sag southeastward and should
become nearly stationary across south central MS/AL by late Monday
night. Deep layer moisture will increase across our forecast area
Monday and Monday night, with precipitable water values improving to
1.25" to 1.5" late. A series of weak mid level impulses embedded
within continued west to southwest flow aloft will move across the
area ahead of and along the approaching boundary, and will aid in the
development of scattered rain showers across the region Monday and
Monday night. The ECMWF still shows some weak instability over the
area, so will also retain mention of isolated thunderstorms in the
forecast Monday. The best chance of rain during the day Monday will
be over interior northwestern portions of the forecast area, with
potential for better development farther south by Monday night.
Highs Monday will be warmer with readings in the lower to mid 70s. A
moist airmass will keep overnight lows Monday night very mild in the
upper 50s to lower 60s over the interior, and in the mid 60s near the
immediate coast. /21

LONG TERM /Tuesday Through Friday/...An unsettled weather pattern
will continue across the forecast area Tuesday and Tuesday night as
a series of shortwave impulses embedded within moist zonal flow aloft
move atop the slow moving/nearly stationary frontal boundary that
will continue to stretch across our forecast area. The front will
finally get a push southward Wednesday, with rain chances decreasing
following its passage late. We will keep POPs in the 30-50% range
across the region Tuesday and Tuesday night, decreasing to around 30%
across most areas by Wednesday, with only a lingering slight chance
of rain by Wednesday night. Dry weather and cooler temperatures are
anticipated Thursday and Friday as surface ridging builds into the
region in the wake of the frontal passage. Above normal temperatures
will persist Tuesday into Wednesday, with highs both days mostly in
the upper 60s to mid 70s. Highs Thursday and Friday should cool back
down to slightly below normal values in the 50s and 60s. Lows Tuesday
night remain mild in the mid 50s to lower 60s, but trend cooler into
the 40s interior/lower 50s coast Wednesday and Thursday nights. /21

MARINE...A moderate to strong northeast wind flow will continue
over the marine area through most of today shifting mostly east this
evening and overnight...continuing through sun afternoon...then
southeast sun night and early mon in response to a weak surface low
developing over the north central gulf shifting northward combined
with a broad surface ridge of high pressure located over the western
Atlantic and eastern gulf. Winds become mostly south to southwest
late mon and continue through early wed ahead of developing cold
front approaching from the northwest. The cold front is expected to
move across the marine area wed into thu leading to a moderate to
strong offshore flow late in the week. Showers and thunderstorms are
also expected to become better developed during the week with the
best coverage occurring wed and wed evening. 32/ee




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