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fxus62 ktbw 211815 
afdtbw 


Area forecast discussion 
National Weather Service Tampa Bay Ruskin Florida 
115 PM EST Sat Nov 21 2009 


Short term...latest visible imagery shows the low pressure system 
over the Texas/la border really taking shape. A band of showers with 
some thunderstorms have developed in the north central Gulf waters 
as they track eastward. Guidance maintains this system taking a 
northeast track towards the Carolinas before losing its upper level 
support and gradually falling apart after it reaches the Atlantic. 
GFS and NAM start to diverge on the placement of the associated 
cold front. GFS wants to push the cold front south over Tampa Bay 
before stalling through the end of the short term. NAM seems more 
reasonable and consistent with pushing the front through the 
Nature Coast before breaking down and washing out by Monday. 
Therefore...have bumped up probability of precipitation across the region for tonight and 
tomorrow morning keeping a much higher chance of rain further 
north while dropping probability of precipitation down to 20 percent by Monday. 


By tomorrow...most of the moisture will remain north of 
Tampa Bay so raised probability of precipitation to 50 percent north of the Bay but kept a 
chance of rainfall across the region. Thermodynamics along and 
ahead of the front are not entirely impressive so will maintain 
just a slight chance of thunderstorms for tomorrow. 


By Monday...front starts to wash out as the associated moisture 
pushes east of the County Warning Area. Weak high pressure begins to build in with 
decreased rainfall chances. 


Daily highs will be right around normal with overnight lows 
running a couple degrees above normal due to the increased cloud 
cover. 


Long term (tuesday night-saturday)...SW flow aloft to keep 
vorticity maxes rotating over the region with a stalled surface 
front over S Florida and a cold front moving into the deep south. 
Our area to be between these surface systems early with deepest 
moisture over southern areas near stalled front for slighter 
higher probability of precipitation while cold front nears through midweek. Cold front to 
move over the area Thanksgiving day with dry and cool high 
pressure building into the region to end the week and into the 
weekend. Temperatures will continue to run around to slightly 
above normal ahead of the front then drop below normal behind the 
cold front late in the week. 






&& 


Aviation...VFR conditions rest of today with increasing clouds 
tonight. Cold front approaching the area to produce MVFR ceilings and 
visibilities with chance of rain as well around around 06z tonight through 
Sunday morning. 




&& 


Marine...rainfall chances will be increasing through tomorrow as 
a low pressure moving north of the area drags a cold front into 
the coastal waters. Winds will increase to the 10-15 knots range but 
will remain below headline status. Main concern with this system 
will be possible thunderstorms producing deadly lightning and 
temporary choppy seas. The front should break down by Monday as 
weak high pressure builds over the waters. 




&& 


Fire weather...no fire weather concerns. 




&& 


Preliminary point temps/pops... 
tpa 81 67 80 66 / 20 40 40 20 
fmy 84 69 83 68 / 20 30 30 20 
gif 83 65 82 65 / 20 40 40 20 
srq 81 67 80 66 / 20 40 40 20 
bkv 82 64 80 61 / 20 50 40 20 
spg 80 70 79 66 / 20 40 40 20 


&& 


Tbw watches/warnings/advisories... 
Florida...none. 
Gulf waters...none. 
&& 


$$ 


Short term/marine/fire weather...20/Barron 
long term/aviation...25/Davis