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fxus62 kkey 081427 
afdkey 


Area forecast discussion for the Florida Keys 
National Weather Service Key West Florida 
930 am EST Thursday Jan 8 2009 


Discussion...in the middle and upper levels...700-200 mb...latest 
available satellite imagery overlaid with streamline analysis as of 
900 am depict the main axis of deep full latitudinal trough 
positioned from The Finger lakes southward to the southeastern Gulf 
of Mexico. A near 100 knot jet @ 250 mb rounds the base of the 
trough and is responsible for transporting cirrus from the Yucatan 
northeastward to across western Cuba and then reaching into the 
Florida Keys. Other than that...the Keys lie beneath a very dry middle 
and upper cyclonic flow. 


At the the surface and in the lower levels...surface to 700 mb. 
Latest available satellite imagery overlaid with surface 
observations and analysis detail a strong cold front extending south 
southwestward to across central Cuba from a near 968 mb low near 
Prince Edward Island. Another weaker cold front is sliding slowly 
southeastward across the middle Mississippi and Tennessee valleys. High 
pressure is centered over the northern Gulf of Mexico. The 12z 
sounding indicated that the Keys lie beneath a shallow northerly 
flow from the surface to 5000 feet...with the presence of a 1 degree 
inversion from 970 to about 920 mb...and a weaker cloud deck about 
that at or above 850 to 800 mb. 


Currently...visible satellite imagery clearly shows the presence of 
a cold front now down to our south over the island of Cuba...with 
just some cirrus crossing over the Keys allowing for sky conditions 
to be categorized as partly cloudy over the islands and adjoining 
waters. Out radar is down for service...but it can be inferred that 
there are likely no measurable echoes in the County Warning Area at this time. Temperatures 
over the islands are between 65 and 70 degrees with dewpoints near 
60 degrees. C-man stations along the Florida reef are mostly 
registering north to northeast winds between 10 and 15 
knots...except 5 to 10 knots at Pulaski Shoal light. 


&& 


Forecasts...short term...rest of today...in the middle and upper 
levels...the main axis of the trough will continue to slide eastward 
across Florida and into the western Atlantic by this evening. Very 
dry cyclonic flow will act to keep rain chances down to negligible 
levels. In the lower and middle levels...high pressure over the 
northern Gulf of Mexico slides eastward. Winds will straiten up out 
of the north. Weather forecast package seems to be on track. May 
make last minute adjustment to up the winds to between 10 and 15 miles per hour 
over the islands and 10 to 15 knots on the Atlantic waters. 


&& 


Marine...no boating issues with better than average conditions 
expected for early January. As mentioned above...will raise the 
winds up a notch this morning...but will stay below headline or 
advisory levels. 


&& 


Aviation...expect VFR conditions today and tonight and the keyw and 
kmth island terminals. Thin high level clouds through late this 
morning will give way to mostly sunny skies through the afternoon. 
Surface winds will be from the north close to 10 knots through the 
afternoon and evening. 


&& 




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


$$ 


Public/marine.................Futterman 
aviation/nowcasts.............04 
upper air/data acquisition.....Ross 


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