Area Forecast Discussion
Issued by NWS Mobile, AL

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FXUS64 KMOB 121248 AAA
AFDMOB

Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
648 AM CST Wed Dec 12 2018

.DISCUSSION...Updated for latest marine discussion below.

&&

.MARINE...A short fuse marine dense fog advisory was recently issued
for Mobile Bay until 9 AM. PORTS observations indicate that
visibility had fallen to around one tenth of a mile near Coast
Guard Sector Mobile and Pinto Island, while local traffic cams
also showed visibility reduced along the bayway and causeway. The
patchy dense fog should gradually lift within the next couple of
hours. /21

&&

.PREV DISCUSSION... /issued 603 AM CST Wed Dec 12 2018/

DISCUSSION...See updated information for land areas and aviation
discussion below.

UPDATE...Our local office rip current checklist indicates that a
high risk of rip currents will likely return Thursday and Thursday
night given a combination of strengthening onshore flow (ahead of
the next approaching low pressure system and cold front), long
period swell, and high tidal ranges. The high risk may linger into
Friday and Friday night as long period swell persists. We have
decided to issue a Rip Current Statement for a high risk of rip
currents along our local beaches Thursday through Friday night.
Surf heights may also increase to 4-7 feet Thursday night through
Friday night, and a High Surf Advisory may eventually become
necessary.

One additional note to mention that we included patchy fog in the
northern Mobile Bay marine zone forecast given a persistent, but
very localized area of patchy fog that has been impacting locations
near the bay way/causeway early this morning. We expect patchy fog
to lift within the next couple of hours. /21

AVIATION...
12Z issuance...Localized IFR or lower visibility restrictions may
impact the KBFM terminal and very localized portions of the area
for the next 1-2 hours. Otherwise, VFR expected today with
increasing high level cloud decks this morning, and lower VFR
decks this afternoon. MVFR ceilings and visibility reductions
could impact portions of the region again tonight. /21

PREV DISCUSSION... /issued 454 AM CST Wed Dec 12 2018/

NEAR TERM /Now Through Wednesday night/...A dry zonal flow pattern
aloft is in place across the central Gulf Coast region early this
morning with surface high pressure also building across the area.
Temperatures are near to slightly below freezing over much of the
area early this morning, except slightly warmer near the beaches.
Some very patchy fog has developed across a few locations near the
coast, but most locations are reporting good visibility as of 4 AM
CST. Expect fog to remain quite patchy in nature and lift prior to 9
AM CST.

The dry zonal flow pattern will continue over the area today, before
mid level flow becomes more southwesterly by tonight ahead of the
next trough that will be deepening over the Rocky Mountains. Surface
high pressure will meanwhile shift eastward across the southeastern
states and adjacent western Atlantic through tonight, allowing for a
return southerly flow to develop across our region. Dry weather is
expected through this afternoon, but cloud cover should continue to
increase as the day progresses. Weak isentropic ascent may develop
near the coast tonight underneath southwest flow aloft, and we will
keep a slight chance of rain in the forecast mainly south of a New
Augusta, MS to Navarre, FL line. We may also have to monitor for
patchy fog development across portions of the area again tonight as
low level moisture increases. Slightly warmer temperatures are
expected today, with highs generally ranging from around 60 to the
mid 60s across the region. Increasing low level moisture should
bring warmer overnight lows tonight with readings in the mid 40s to
around 50 over the interior, and in the 50s near the immediate
coast. /21

SHORT TERM /Thursday Through Friday night/...An upper trough
moves across the southern plains and forms a deep upper low over
Texas on Thursday. An associated sfc low occludes while moving
eastward. Strong deep layer lift will spread across the area from
the west starting Thursday afternoon through Thursday night. This
will bring widespread showers and some thunderstorms to the area.
Only weak destabilization is expected ahead of this system due to
the lack of significant modification of the airmass. As a result,
only weak CAPE values are expected along the coast and this is
where SPC has outlined a marginal risk of severe thunderstorms.
The main threat will likely be locally heavy rain. The heavy rain
will move east of the area Thursday night, however the upper low
will slowly move across the area on Friday. This will keep
conditions cloudy with scattered showers. /13

LONG TERM /Saturday Through Tuesday/...Dry conditions continue
through the extended period as the large, deep system continues
eastward away from the area and into the western Atlantic.
Temperatures will be near or slight below seasonable values
through the period, roughly near 40 at night and around 60 each
day. /13

MARINE...Surface high pressure will build across the eastern Gulf
of Mexico today, allowing winds to become southeasterly to southerly
over the marine area. Onshore flow will strengthen tonight into
Thursday night as the gradient increases between high pressure
shifting into the western Atlantic and a low pressure system and
cold front approaching from the west. Wind speeds will likely
increase to Small Craft Advisory levels Thursday into Thursday
night, with seas also building to 7-10 feet offshore. Small Craft
Advisory issuance will likely become necessary later today or
tonight. We may also have to monitor for near gale force gusts well
offshore by Thursday night. Showers and a few storms will spread
over the marine area ahead of the approaching front Thursday and
Thursday night, and a few storms could become strong to marginally
severe. Moderate to strong westerly flow and rough seas will
continue Friday into early Saturday, followed by moderate offshore
flow and subsiding seas this weekend. /21

&&

.MOB WATCHES/WARNINGS/ADVISORIES...
AL...High Rip Current Risk from Thursday morning through late Friday
     night for ALZ265-266.

FL...High Rip Current Risk from Thursday morning through late Friday
     night for FLZ202-204-206.

MS...None.
GM...Dense Fog Advisory until 9 AM CST this morning for GMZ630-631.

&&

$$

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