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fxus62 kkey 212007 
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Area forecast discussion for the Florida Keys 
National Weather Service Key West Florida 
405 PM EDT Thursday Aug 21 2008 


Discussion... 
showers have been isolated to scattered in the Key West service area 
late this morning and thus far through the afternoon. A strong 
cluster of storms was concentrated in the Atlantic waters just off 
the Upper Keys a while ago...and the larger area of shower/thunderstorms on 
the extreme southern periphery of ts Fay has diminished in area well 
north of our Gulf waters. Winds are moderate out of the 
southwest...with an area of fresh mostly confined to the northeast 
portion of our Atlantic waters. Temperatures range from the upper 
80s to lower 90s along the island chain under partly cloudy skies. 


Forecast reasoning has not changed much from previous thoughts. The 
official forecast for ts Fay crossing the northern portion of 
Florida westward on Friday...and then skirts the coastline of the 
Panhandle on Saturday. Locally...this will keep a relatively deep 
southwesterly breeze in place at least through early Friday...before 
slackening and backing more to the south by Friday night. The 
Atlantic ridge that was earlier thought to lift northward and become 
aligned north of the Keys is now less defined through the middle 
portion of the weekend. And the pattern actually looks much more 
relaxed from daytime Saturday through the middle portion of next 
week. So have made only minor adjustments to our surface wind grids 
for any of the middle and late periods of the forecast. For 
now...any waves working through the Atlantic should stay south of 
our latitude. Precipitable water should remain at or above 1.8 
inches with a discernible drier strip wrapping north of the 
Keys...but on the southern extreme of ts Fay. And if the GFS is to 
be believed...we will be at or above 2.0 inches all the way through late 
Sunday. This looks overdone though...but we are expected to remain 
quite moist and unstable. With no discernible large scale lifting 
mechanism expected to move through...will keep our probability of precipitation at or 
slightly above climatology for each forecast period of this forecast. 


&& 


Marine... 
as stated above...there is a lingering pocket of fresh breezes off 
of the Upper Keys...compounded by a larger area of convection 
earlier in the afternoon. On this upcoming issuance...plan to 
separate the Atlantic waters adjacent to the Upper Keys away from 
the remainder of the Atlantic marine zones and put an exercise 
caution headline for small craft operator to allow seas more time to 
settle. Otherwise...the slackening and backing trend to all areas 
will progress through the weekend...and likely will be light and 
variable through the bulk of the weekend and into early next week. 


&& 


Aviation... 
tonight...VFR conditions will prevail at the keyw and kmth island 
terminals. The Florida Keys will remain in a southwest flow between 
Tropical Storm Fay over the northern part of the Florida Peninsula 
and a low level ridge to the south of the Keys. Isolated showers and 
thunderstorms with brief MVFR/IFR ceilings and/or visible will be likely 
within any isolated showers and thunderstorms that do impact the 
keyw or kmth island terminals. Surface winds will average from 240 
degrees at 10 to 15 knots...but gusts over 25 knots will be possible 
within stronger showers or thunderstorms. 


&& 


Preliminary point temps/pops... 
Key West 80 90 80 90 / 30 30 30 30 
Marathon 80 91 80 92 / 30 30 30 30 


&& 


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


&& 


$$ 


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aviation/nowcasts.......daf 
data acquisition........tf 


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