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Area Forecast Discussion (AFD)

Issued by Key West, FL (KEY)

FXUS62 KKEY 192000

Area Forecast Discussion
National Weather Service Key West FL
300 PM EST Mon Feb 19 2018

Mid to upper level ridging centered east of the Florida Peninsula
and the Bahamas supports an impressive anticyclone over the 
extreme western North Atlantic. East to southeast breezes are
nearing 20 knots at most exposed marine locations. Locations along
land and north of the island chain are backed slightly and reduced
5 knots. Temperatures are near or just above 80, with dewpoints
near 70. Fast moving showers have persisted all day, although more
isolated now compared to around sunrise this morning. 

Multiple satellite sources, in conjunction with the 700/500mb
derived vorticity analyses from CIMSS, highlight a deep--yet 
weak-- undulation in the easterlies south of Andros. This feature 
has been well forecast for several days to push through the Keys 
tonight. Rain chances near 60% have been retained, followed by a 
marked drop in shower activity Tuesday on the backside of the 
moisture max. The anticyclone over the western North Atlantic will
persist Tuesday night through Saturday, featuring persistent 
east-southeast breezes and slight rain chances. Periodic 
wind/moisture surges will temporarily increase rain chances along 
the arcing convergent fronts pushing to the west-northwest. We 
have retained the previous forecast which advertises 20% rain 
chances Wednesday night through Thursday night, slightly above the
average for this time of year. The anticyclone will break down
Saturday night through Monday, relaxing breezes, and shaving
overnight lows back to near 70. Otherwise, expect afternoon highs
to reach the lower 80 through the long term. 


A ridge of high pressure will extend west into the southeastern 
United States and northern Florida tonight through Friday. This 
ridge will begin to shift southward Friday night through Saturday 


Current visibile satellite imagery, upstream satellite derived 
moisture products, and forecast soundings indicate rain chances 
returning to the terminals overnight. A weak undulation in the
easterlies will push through the terminals between 00 and 12Z. We
have included TEMPO MVFR episodes in the TAFs due to the
expectation of fast moving, low topped showers. 


GM...Small Craft Advisory for GMZ031>035- 



Data Collection......CLR

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