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fxus62 ktae 030811 cca 
afdtae 


Area forecast discussion...corrected aviation 
National Weather Service Tallahassee Florida 
236 am EST Wednesday Dec 3 2008 


Synopsis...most of North America is dominated by a long wave trough 
this morning. There are several short waves of note rotating through 
it. The one that resulted in last night's light rain event is 
exiting the middle Atlantic coast. The next in the pipeline to affect 
our weather is diving southeastward toward The Four Corners region. Surface 
analysis shows another Arctic front pushing southward and eastward across the 
northern plains and upper lakes. A weak low pressure system is organizing 
in the Central High plains in response to The Four Corners energy. 
Over our area, high pressure has slipped just east of US and is 
centered over southeast Georgia and northern Florida. Skies are clear and winds calm. 
Temperatures radiated quickly around sunset, but the descent has slowed. 
The normally coldest areas dipped below freezing around midnight and 
these areas should bottom out in the upper 20s for the most part 
come sunrise. Many areas will see frost. 


&& 


Short term...today through Friday. 
After a frosty start, temperatures will rise quickly in this dry air mass 
and under full sun, but will still maximum out several degrees below 
normal, a common occurrence since middle Nov. Temperatures will not be quite 
as cold tonight with most areas dipping to the middle 30s. However, a 
widespread frost is possible over our Georgia and Florida Big Bend zones as 
dew point depressions drop to zero for most of the night. The 
upstream short wave and associated frontal system will enter the 
lower MS valley by 12z Thursday. The upper support will be weakening as 
it approaches and that trend will continue as it eases across the 
forecast area from late Thursday through Friday. Model consensus has slowed 
the system over previous runs, but the NAM looks a bit too slow and 
the GFS solution was preferred. Probability of precipitation were based on a combination of 
the latest mav and gridded MOS for the most part. It should be noted 
that European model (ecmwf) and sref probability of precipitation are higher than this. Ahead of the front on 
Thu, temperatures will actually rise a bit above normal with upper 60s north to 
lower 70s S. Thursday night mins will generally be in the middle 40s. 


Long term...Friday night through Wednesday. 
The mean upper pattern will feature a series of short wave troughs 
moving quickly southeastward across the central and eastern Continental U.S. From southwestern Canada. 
Weak surface high pressure will move quickly across the southeastern states 
Friday night...with the next clipper system exiting the East Coast by Sun 
morning. With Gulf moisture effectively shut off...expect a dry cold 
frontal passage overnight Sat. High pressure system behind this 
front will usher in a cooler and drier air mass than its predecessor 
with below average temperatures sun and Monday. The high exits the East Coast Monday 
night with onshore flow increasing moisture and temperatures ahead of the 
next trough and cold front...which will affect the County Warning Area Tuesday and Tuesday 
night. The 02/12z Euro is trending slower and deeper with this 
system than the Gem. 


&& 


Marine...today through sun. 
Seas continue to gradually subside from this morning's advisory 
event and with the winds having been light for many hours, we are 
mainly seeing residual swell. Winds will gradually veer over the 
next few days, to Ely today, southeast tonight and S for Thursday into Thursday 
night. A gradually wind shift is on tap for late Thursday night through 
Friday as the front oozes across the area. Winds off the Taylor and 
Dixie County coast will not switch around to northwest until Friday night. 
These northwest winds will then kick up to exercise caution levels by Sat 
night and sun, possibly even reaching advisory levels. 


&& 


Aviation...VFR conditions will prevail for the next 24 hours. Clear 
skies through this morning will give way to a few afternoon cumulus. Near calm 
winds overnight will become southeasterly 5-10 knots by late morning...then 
light after sunset. Upper level moisture in the form of scattered cirrus will 
spread from west to east during the evening. 


&& 


Fire weather...drier air mass will continue today with critical 
durations of sub-35 percent relative humidity over much of the Florida Big Bend this 
afternoon. Consequently...a red flag warning will be issued. No red flag 
concerns for Thursday and Friday as the next cold front brings increasing 
moisture to the region. 


&& 


Hydrology...the Ochlockonee appears to be cresting at Concord at 
just under 33 feet. This is a moderate flood for that point but below 
the stage where significant impacts begin. We plan to update the 
warning to indicate that the higher crest on Thursday is no longer 
anticipated. Flooding is not forecast at the downstream gage in 
Havana. The only other point in flood across the hsa is the 
Withlacoochee at Valdosta, which is near crest. The forecast is on 
track for this point. 


&& 


Preliminary point temps/pops... 
Tallahassee 61 34 70 47 64 / 00 00 10 40 30 
Panama City 62 46 71 53 64 / 00 10 20 40 20 
Dothan 60 40 68 47 60 / 00 10 40 40 20 
Albany 59 35 67 46 60 / 00 05 30 40 20 
Valdosta 60 35 69 46 62 / 00 00 10 40 30 
Cross City 64 36 72 44 72 / 00 00 05 20 30 


&& 


Tae watches/warnings/advisories... 
Alabama...none. 
Georgia...none. 
Florida...red flag warning 1 to 5 PM EST for the following zones: 
Dixie...Gadsden...Jefferson...Lafayette...Leon...Madison and 
Wakulla. 
GM...none. 


&& 


$$ 


Aviation/fire weather/long term...jamski 
rest of discussion...wool