Area Forecast Discussion
Issued by NWS Mobile, AL

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FXUS64 KMOB 102325 AAA

Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
525 PM CST Sun Dec 10 2017

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


00Z issuance...VFR conditions will prevail through the next 24
hours. /13


.PREV DISCUSSION... /issued 344 PM CST Sun Dec 10 2017/

NEAR TERM /Now Through Monday/...The mean longwave trough over the
eastern CONUS will become reinforced late tonight into Monday. The
dry northwesterly flow pattern aloft will persist across the central
Gulf Coast region on the base/southwestern periphery of this feature
through the near term. Mainly clear skies and dry weather can be
expected through Monday afternoon. A surface ridge of high pressure
will nose eastward across the Gulf of Mexico and Florida peninsula
through Monday afternoon, promoting a light west to southwest flow
across our region. Temperatures will be a bit warmer tonight, though
a light freeze is still anticipated across interior southeast
Mississippi and southwest Alabama. Plenty of sunshine and light
southwesterly surface flow will contribute to a continued warming
trend Monday afternoon. Highs are expected to reach into the lower
to mid 60s. /21

SHORT TERM /Monday night Through Wednesday night/...The Short
Term is pretty quiet, precip and temp-wise. An upper trough
remains entrenched over the eastern Conus through the period, with
pieces of energy rotating through. Monday night into Tuesday, a
surface ridge that has built east over the northern Gulf continues
to bring dry, seasonable flow to the Lower Mississippi River
Valley and southeast. A strong lobe of energy rotates through the
trough, pushing a re-enforcing front across the area Tuesday into
Tuesday night, and below seasonal temps return for Tuesday night.
With essentially no moisture return ahead of the fropa, no rain,
maybe a bit of an increase in cloud cover, is expected. More
energy moving into the eastern upper trough later Tuesday night
into Wednesday pushes surface high pressure east along the
northern Gulf coast, bringing light southwesterly flow to the area
by Thursday morning. Temperature moderate upward. but not quite
reaching seasonable levels. Moisture level also begin to increase
with the switch in low level flow Wednesday night.


LONG TERM /Thursday Through Sunday/...the Extended continues to
be a challenge, especially late in the work week. Another strong
piece of energy dives into the eastern upper trough late Thursday
into Thursday night. The 12z ECMWF is advertising a deeper/slower
swing than the 12z GFS. The result is the op ECMWF advertising a
surface low forming over the western Gulf Thursday night into
Friday, then tracking it ene over the north-central Gulf. The
result is a wetter/cooler solution then the GFS. As I write, the
ECMWF ensemble mos has become available, with the ensemble mean
significantly drier, but not warmer than the op run. Have went
with a GFS/ECMWF blend with temps and toned down, but not
completely dried out, the ECMWF PoPs for Thursday night into
Friday night. A warm-up occurs thursday ahead of the passing
system, with both advertising a cool-down as post fropa cold air
moves over the area beginning Friday.

The last piece of shortwave energy moves through northern parts of
the eastern upper trough, pushing another surface high east over the
northern Gulf coast, and restoring onshore flow by
Saturday(GFS)/Saturday night(ECMWF). Temps moderate upward through
the weekend as a result, with well above seasonal temps, maybe a
shra, returning for Sunday.


MARINE...A surface ridge of high pressure will continue to build
eastward across the Gulf of Mexico through Monday afternoon,
resulting in a light to moderate northwest to west flow across the
marine area. Westerly flow increases Monday night in advance of an
approaching front, with winds gradually turning northwest Tuesday
then more northerly Tuesday night following the passage of the
front. Wind speeds will approach Small Craft Advisory levels
offshore beginning late Monday evening, and may persist into late
Tuesday evening. An advisory may need to be issued within the next
12-24 hours. Winds diminish Wednesday as a surface ridge builds back
over the Gulf of Mexico. Another round of moderate to occasionally
strong west to northwest flow may return Thursday into Friday ahead
of and following the passage of another cold front. /21




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