AREA FORECAST DISCUSSION…UPDATED
NATIONAL WEATHER SERVICE TALLAHASSEE FL
628 AM EST Thu Dec 27 2012

Updated Aviation Discussion.

.NEAR TERM [Through Tonight]…
Quiet weather is shaping up for today as cool high pressure builds
into the area. Morning cloud cover should gradually erode during
the day with skies expected to be mostly clear areawide by
tonight. The cool airmass is expected to keep high temperatures
below average this afternoon.

Heading into tonight, as the surface ridge moves closer to the
area, decent radiational cooling conditions are expected. Lows are
expected to bottom out near freezing over a large portion of the
area away from the coast with the coldest readings over the
southeast big bend. Areas of frost look likely away from the coast
and are mentioned in the forecast.

&&

.SHORT TERM [Friday Through Saturday]…
The pattern is expected to remain progressive through the short
term with the next shortwave arriving late Friday into Saturday
morning. An area of low pressure is expected to develop near the
Gulf coast and move eastward through the area. Model agreement is
fairly good on the timing of this system, so PoPs were bumped up
to 70-80 percent on Friday night. A warm front is expected to
straddle the coast with the greatest surface based instability
remaining just offshore. However, there appears to be enough
elevated instability to keep some chances of thunder over most of
the area. In fact, if the 00z NAM instability forecast verifies,
then there could be some stronger storms over the coastal waters
with favorable shear for organized convection. It is worth keeping
an eye on this to make sure there doesn`t end up being a low end
threat for a stronger storm along the coastline, but right now the
threat seems limited.

&&

.LONG TERM [Saturday Night through next Thursday]…
The period will begin with another Sfc Low exiting our region
quickly to the NE with a strong and cold Ridge of High Pressure
building in from the NW. This Ridge is expected to strengthen to
between 1030 and 1035mb and will be situated right over the CWA on
Sunday and Monday. This will set the stage for a possible short
duration light freeze on Sunday morning, with a likely long
duration light freeze (with a poss. Hard Freeze in some colder
locations) for Monday morning. Daytime highs on Sun. and Mon. will
also be held down several degrees below climo. For the remainder
of the period, however, an extended period of unsettled conditions
appears likely, as a series of weak waves of low pressure ride
E-NE along an elongated boundary. This boundary will be fairly
close to stationary over our CWA Mon. Night through Wed. Night, as
it will be essentially trapped between a strong Upper Ridge over
the SE Gulf of Mexico, and a weak Upper Trof swinging in from the
NW. At this time, this setup would favor periods of beneficial
rain over our area, with any Tstms appearing unlikely. It should
be noted, however, that the GFS and CMC are in good agreement with
this scenario (which we are fcsting), while the past 2 runs of the
ECMWF are much slower with moisture advection, holding off the
next batch of rain until Wed. Night and Thurs.

&&

.AVIATION…
[Through 12Z Friday] The expected MVFR level Cigs have been very
steady at DHN and ABY throughout the night and early morning
hours, while TLH and VLD have been going Sct at times. It did take
longer than expected for the Cigs to reach ECP (by 1030Z), but the
latest 11-3.9 micron Sat. Imagery shows they are likely to remain
Bkn-Ovc for about 2-3 more hours. DHN and ABY should also be the
last to scatter out and return to VFR (by 15Z), with all terminals
expected to remain at VFR levels for the rest of the period.

&&

MARINE…
Winds and seas will continue diminishing today as high pressure
builds south toward the marine area. The next storm system will
begin to develop across the Gulf on Friday evening with winds and
seas expected to reach advisory levels this weekend.

&&

.FIRE WEATHER…
Although afternoon relative humidities will be noticeably lower
today and Friday, they are not expected to be low enough (and ERCs
will not be high enough) to cause any concerns. With another
wetting rainfall expected on Friday night and Saturday, no Red
Flag concerns are expected for the next several days.

&&

.HYDROLOGY…
Area rivers are expected to remain below flood stage for the next
several days. A general half inch to one inch of rain is expected on
Friday night into Saturday with the highest amounts expected to be
near the coast.