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fxus62 kkey 231552 
afdkey 


Area forecast discussion for the Florida Keys 
National Weather Service Key West Florida 
1052 am EST Monday Nov 23 2009 


Discussion... 
a deep and strong west to southwest current prevails aloft over the 
Gulf of Mexico and Florida Peninsula east of a developing long wave 
trough...while a deep anticyclone remains centered just east of the 
Bahamas. Currently...air flow remains anticyclonic in the 850-500mb 
layer over the Keys with resulting synoptic-scale subsidence and 
drying through much of the atmospheric column. This is evidenced well 
on the Key West morning rawinsonde observation which revealed several 
dry and stable layers up through 500mb. At the surface...the mean sea level 
pressure pattern in the Keys is quite weak at the moment owing to a 
departing low pressure area off the Carolinas and very weak ridge of 
high pressure over the Florida Peninsula. This pattern will change 
slowly starting later today and tonight as pressures begin to fall 
over the western Gulf and rise over the Carolinas and Georgia. 
Currently...the skies across the Florida Keys are filled with 
abundant fast-moving cirrus thanks to the subtropical jet stream 
overhead. A few heavy showers have popped up along a convergence line 
south of the Marquesas Keys...with a slow northward movement. The air 
mass is basically maritime tropical with air temperatures now in the 
lower 80s and dewpoints in the lower 70s. A weak and disorganized 
baroclinic zone remains over the shelf waters from North Carolina to 
Louisiana. 


The current forecasts are on track with no updates planned this 
afternoon. 
&& 


Marine... 
light breezes across much of the service area this afternoon will 
come up a few knots by dark...turning mainly out of the east. A few 
moderate to heavy showers will develop and move slowly northward. 
&& 


Aviation... 
rest of today...VFR conditions will prevail at the Key West and 
Marathon island terminals. Just a few cumulus clouds with cloud 
bases will be found at or above 2000-2500 feet. Ample cirrus will also 
continue with bases averaging between fl250-300. Light and variable 
winds should become light and easterly tonight. 
&& 


Key watches/warnings/advisories... 
Florida...none. 
GM...none. 
&& 


$$ 


Public/marine.........Kasper 
aviation/nowcasts.....Futterman 
data collection.......Ross/Nelson 


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