AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
230 PM EST Mon Dec 5 2011

.SHORT TERM (Tuesday through Wednesday night)...
A long wave trough with a strongly positive TILT will extend from
northern Quebec SWWD to the American Desert SW at the start of the
period. A DOWNSTREAM RIDGE will remain parked over the FL peninsula.
Surface high pressure will be centered SE of New England and
continue to ridge swwd to FL. A slow moving cold FRONT will extend
the LENGTH of the Appalachians and then swwd across AL to the N.
Central Gulf of Mexico. We continue to see differences among the
various models on the speed with which energy in the southern
portion of the long wave trough will progress eastward across the
southern U.S. This also maintains differences in the timing of the
cold frontal passage. The 00Z Euro is on the fast side of the models
with the 12Z NAM on the slower side. The GFS will be used as a
compromise. Regardless of which model verifies best, the progress of
the front should be pretty slow. We also anticipate some
post-frontal precip with this system. Deep layer WSW winds aloft
over the warm sector will warm the mid levels and limit instability.
Therefore, little to no thunder is expected and none is included in
the forecast.

Looking at specific TEMP/POP trends, substantial differences can be
expected at times across the forecast area. TEMPS should remain
uniformly mild mild to warm across the region on Tuesday with highs
in the mid 70s for most areas and upper 70s to around 80 over VLD
and the eastern FL Big Bend. POPS will range from LIKELY NW to
slight CHANCE SE. The front will begin to work its way slowly
eastward across the CWA Tuesday night. Temps will remain mild ahead
of it with lows in the 50s and 60s. Another round of fog is possible
ahead of the front across the eastern zones. On Wednesday, the front
will continue its trek across the area, but it will take until
evening to clear the Suwannee River. PoPs will range from likely N
to chance S. There will be quite a range in temps with S. Central GA
and the eastern Big Bend counties getting into the mid to upper 70s
once again and those stuck behind the cold front over SE AL and the
central FL Panhandle seeing little rise in temps during the day.
Depending on frontal timing, areas of light RAIN will come to an end
Wednesday night, although the CURRENT forecast allows a slight PoP
to linger into Thursday morning. MIN temps will get as low as the
mid 30s by around 12Z Thursday over the NW zones with lower to mid
40s to the SE.

.LONG TERM (Thursday through next Monday)...
The models are now in much better agreement on the timing of the
next low pressure system to impact the local region. The 12z ECMWF,
12z Canadian and 00z GFS show the cold front passing through all but
our easternmost zones at the beginning of the extended period. By
daybreak Thursday the front is forecast to be over or just south of
Cross City. Will hold on to a slight PoP across the Big Bend and
Valdosta regions Thursday morning to account for the system
possibly lingering a bit longer. After the SHORTWAVE and associated
cold front pass, additional shortwave energy will rapidly drop to
the southeast from the northern plains allowing a trough to dig
across the eastern U.S. This will send a dry cold front through the
Tri-state area over the weekend bringing with it a re-enforcement of
cold dry AIR. Temperatures will be below seasonal levels throughout
the extended period with freezing or near freezing min temps
possible for Sunday morning.