AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
830 PM EST Tue Jan 10 2012

...There is a slight Risk of Severe Storms Tonight THRU Wed morning
for SE Ala and for the FL Panhandle...

.SYNOPSIS...
Around 7-730 pm, some small MESO-scale feature moved thru southern
Georgia generating brief but strong WIND gusts with multiple trees
down across Decatur County.

AT UPPER LEVELS...
The large scale split FLOW pattern this Tues evening is highlighted
in NRN stream by troughing over WRN states and broad ridging EWD to
ERN seaboard. Conversely, SRN stream more amplified with ridging Wrn
and Ern states and deep TROUGH in between with 553DM closed LOW over
NE TX. Potent SHORTWAVE approaching LWR MS Valley.

Over the next 12-18 HRS, this low will progress EWD to MS/AL in
response to Nrn stream trough amplifying over Nrn Rockies/Plains.
Assocd speed MAX approaching 80KT and ahead of H5 low PROGGED to
eject NEWD across SRN AL/FL Panhandle and gradually weaken AS upper
low opens up. Shortwave moves from Lwr Ms Valley thru TN Valley and
strong cooling and HEIGHT falls over LA/MS this evening that will
push EWD into the Wrn CWA overnight.

AT LOWER LEVELS...
Analysis shows an occluding 1006 MB low centered over SE AR with a
QUASI-STATIONARY boundary located from this low ESE to across
S/CNTRL Al/SRN GA ewd to Atlc. The warm sector continues to be
marked by weak INSTABILITY (MU Capes 250-500 j/kg) but strong SHEAR
(06km 60-70kt). Another quasi-stationary coastal FRONT had SET up
about 50 NM or so south of the FL Panhandle/AL Coast. The result is
that the true surface-based instability continues to be well
offshore and will prove difficult to go NWD toward the Gulf Coast
rest of tonight. In fact,UPSTREAM radars earlier indicated that
thunderstorms struggled to develop in the warm sector of Ern LA/MS
due primarily to weak lapse rates, extensive CLOUD cover and limited
instability. In fact, this extensive cloud cover emanating from
ongoing upstream convective clusters kept local conditions mostly
CLOUDY and cooler on Tuesday.

&&

.REST OF TONIGHT INTO EARLY WEDNESDAY.
Elevated thunderstorms will be possible towards midnight over
interior sections with best forcing occurs as the upper low
approaches the area. The primary forecast question will be the
potential for severe weather but this looking less and less LIKELY.
With CURRENT OVERRUNNING over cold front producing extensive
cloudiness and warm MID layers, chances of generating enough
instability to produce WIDESPREAD surface based land thunderstorms
not HIGH. Regional meso-analysis seems to confirm that the area for
best surface-based instability will remain along the coast and
especially offshore and will likely only gradually pivot northward
toward the Gulf Coast States as the surface low continues to
occlude, deepen and lift northward into Nrn AL by 12Z Wed dragging
cold front to Lwr Ms Valley later tonight and across our CWA on Wed.

Still looks like a low CAPE/high shear generally linear event.
The kinematic fields and 500 mb height falls remain reasonably
impressive locally as the upper low drives ENE through SRN AL with
cooling aloft helping to raise DEW points to near 60F...before
lifting into N GA on Wednesday allowing for some destabilization.
However,lapse rates meager restricting MU Cape to below 500 j/kg and
this will focus along a very narrow axis directly ahead of the
cold front. However, somewhat veered but still strong LLJ near 50kts
crosses Ern Gulf states with strong warm sector moving progressively
NWD. Overall, all this kinematic and dynamical forcing will likely
be unable to overcome the prohibitive thermodynamic environment at
the surface for more than ISOLATED severe weather. Based on upstream
events, even the CHANCE of non-severe storms is diminishing with
time. If any strong and especially any severe weather occur, it
looks to be confined to coastal areas of the FL Panhandle/WRN Big
Bend and especially over the adjacent coastal waters where where
shear is greatest and where some storms may contain ROTATION
producing brief damaging winds. Cannot completely discount an
isolated TORNADO. Thunderstorms look to begin around 3AM EST Wrn
counties and ending around SUNRISE Ern most counties. SPC still has
area in a 15% chance of severe wind gusts and a 5% chance of
tornadoes.

One thing that is clear is that it will RAIN, so POPS remain at 100
percent across much of the area. Significant rains are not
anticipated, but it should be a good soaking rain with most areas
receiving between 0.75 and 1 inch by Wednesday, the bulk of which
should FALL prior to sunrise. Temperatures overnight will be quite
warm given the thick cloud cover. Increasing boundary layer winds
will keep FOG from becoming the problem experienced in recent
nights. The rain will end from west to east Wednesday morning,
followed by clearing skies and slightly drier AIR behind the cold
front. Temperatures will return to near average on Wednesday.

&&

.MARINE...Winds and SEAS will be on the increase rest of tonight
with a period of ADVISORY level conditions starting west to east.
These conditions should continue through Wednesday Afternoon before
diminishing.

&&

.AVIATION...
Cold front will approach and begin to cross the area through the
NIGHT. Large expanse of light to moderate rain has been impacting
KECP...KTLH...and KVLD the past FEW hours with generally periods of
MVFR cigs/VIS. Appears this main area of rain will be pushing east
by the early morning hours, however anticipate another round of
showers and a few thunderstorms to move through associated with the
actual cold front. Therefore rain will be in the forecast through
the majority of the night for all terminals. Expect a gradual
lowering of the cigs through the overnight with widespread MVFR and
tempo IFR conditions after midnight. Cold front will cross KDHN and
KECP during the late night hours, and the remaining eastern
terminals during the first few daylight hours of Wednesday.
Anticipate a few hours of MVFR cigs post-frontal, followed by
conditions improving to VFR for the afternoon hours.