Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Tallahassee Florida
808 PM EST Wed Dec 4 2013
Near term [through tonight]...
the main concern overnight is the potential for dense fog to
develop. Currently there are a few scattered showers moving off
the Gulf into the western Florida Panhandle and southeast
Alabama, but these should gradually diminish through the night and
become less of a factor. There is also a large cirrus canopy
moving overhead, but despite this almost all of the statistical
and hi-res guidance continues to develop areas of dense fog later
tonight. Dense fog did develop last night with a similar
environment, so the only real limiting factor tonight is the high
cirrus canopy. Some sea fog over Apalachee Bay is also still a
possibility, although models have been too aggressive in
developing that so far. The reason may be that higher dewpoints
have been slower to advect into that area due to more of a south-southeast
wind rather than a due south or southwest wind to really get the
higher dewpoints over Apalachee Bay. However, the latest msas loop
does show a gradual progression northward of higher dewpoints, so
some advection fog is still possible with nearshore SSTs now in
the upper 50s to lower 60s and upper 60s dew points advecting over
that. Overall, there is little change to the previous forecast for
tonight, and a dense fog advisory may still be needed later
tonight. Overnight lows will once again be 15-20 degrees above
Short term [thursday through Friday night]...
an upper level ridge will continue to build from the Gulf across
the western Atlantic as a western trough swings into the Midwest.
Elsewhere in the Continental U.S. An Arctic airmass will push south into the
Southern Plains stretching to the Ohio River valley, resulting in
a band of significant icing and snow. A 5910m ridge across central
and South Florida will allow daytime highs to climb 15 degrees
above normal for the next couple of days. Highs will be near 80
Thursday and Friday, with mild overnight lows in the lower to mid
60s (which are close to the normal high temperatures for early
Dewpoints have increased from the lower to mid 50s to the lower to
mid 60s in the past 24 hours and will remain in the 60s through
the period. This warm and moist flow over the relatively cooler
shelf waters of Apalachee Bay will likely result in sea fog which
will move inland Thursday night. Friday night the flow decreases
in advance of a cold front which will weaken advection, but we
still expect areas of fog. Fog will be slow to burn off, likely
persisting into late morning tomorrow and Friday, due to the very
moist boundary layer and low sun angle.
The warm and moist onshore flow will result in isolated showers,
mainly north and west of Tallahassee tomorrow and Friday. Also
we cannot rule out an isolated afternoon thunderstorm with the
weak surface instability. As we close in on the weekend, the
Midwest cold front will approach the se, moving to the Florida
Panhandle, southeast Alabama and central Georgia by late Friday night.
Long term [saturday through wednesday]...
this period will feature a couple of frontal systems. The first
cold front moves into the southeast late Friday night, but becomes
stationary from the central Florida Panhandle to southeast Georgia by
Saturday evening. This front then pushes back north as a warm
front Saturday night, meaning that our area never gets into the
deeper moisture or lift behind the front. The drier return flow on
Sunday is short-lived, as a second much stronger cold front pushes
through the area late Monday night into early Tuesday. This front
has the upper support to push all the way south across the Florida
Peninsula, putting al, GA, and northern Florida well into the cold air.
As a result, the very warm temperatures of the past week could
drop by 15 to 20 degrees behind the front on Tuesday and
Wednesday, with readings in the 50s in southeast Alabama and SW Georgia
to the 50s and lower 60s across northern Florida.
Precipitation will generally be scattered through the period with
a chance of thunderstorms along and ahead of the first front
Saturday and again with the much more vigorous front on Monday.
[through 00 UTC friday] fog is expected to develop overnight
across the entire area beginning between 03-06 UTC. LIFR
visbys/cigs are forecasted at all sites for an extended period
before conditions start to improve between 15-16 UTC. After 19z,
VFR is expected all terminals except ecp where they may take
longer to break out of lowered ceilings.
moderate onshore flow is forecast to continue over the coastal
waters into the weekend, with wind speeds occasionally approaching
exercise caution levels. Sea fog is expected to be an issue
beginning later tonight, especially over Apalachee Bay.
Conditions will continue to favor sea fog development through at
red flag conditions are not expected the next several days. Areas of
dense fog are expected to develop over the next several nights with
poor mixing and light winds. A cold front will bring much drier air
to the region for Tuesday and Wednesday. However, the relative humidity is
currently forecast to remain above critical levels.
while there is a chance of rain through the weekend, total quantitative precipitation forecast
amounts will not be enough to have an impact on river stages.
Preliminary point temps/pops...
Tallahassee 62 80 60 79 62 / 10 10 10 10 10
Panama City 66 77 66 77 65 / 20 20 10 10 20
Dothan 63 80 63 80 59 / 30 30 10 10 30
Albany 61 81 61 81 63 / 20 20 10 10 20
Valdosta 60 81 61 80 61 / 10 10 10 10 10
Cross City 60 81 59 81 58 / 10 10 10 10 10
Apalachicola 66 75 64 75 65 / 10 10 10 10 10
short term/long term...Hollingsworth