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Area Forecast Discussion (AFD)

Issued by Key West, FL (KEY)

FXUS62 KKEY 141825

Area Forecast Discussion
National Weather Service Key West FL
225 PM EDT Tue Aug 14 2018

Observations across the islands, as well as marine platforms along
the reef, have been generally between 5 and 10 knots from the 
southeast over the past several hours. Key West radar is picking 
up some a few weak convective cells over the Florida Straits and 
Gulf waters. A few thunderstorms have developed over the Gulf 
Waters, but quickly collapsed. Some cumulus streamers can be 
found off the larger islands in the lower Keys, but none have 
spawned any showers. Visible satellite imagery is showing a slow 
clearing over the waters east of the convective cells in the 
Straits. Cira 700-500mb LPW confirms that the much anticipated SAL
is now sitting on our doorstep, just beginning to seep into the 
eastern boundaries of our Atlantic waters. NUCAPS soundings 
analysis reveals this may be one of our stronger SAL events this 

Tonight through Friday night...For the first time this summer, it
seems the Atlantic ridge is finally taking hold and will dominate
our weather patterns over the next seven days. This will keep the
Keys and coastal waters in prevailing east to southeasterly flow 
through the lower boundary layer. The factor that will most 
dictate sensible weather (rainfall) over this periods will be 
available moisture to allow convective development. From now 
through Friday night the SAL will dominate and moisture throughout 
the boundary layer will be limited. The GFS is showing a small 
break in the dry air on Wednesday evening, possibly related to the
northern extent of a passing wave in the Caribbean, but the 
European is not as bullish on the moisture plug. Overall, the 
chance of rain will be suppressed through this period and 
convective coverage will be isolated at best.


Saturday through Tuesday...Both available GSMs are showing another
prolonged break in the dry air on Saturday through Monday. Likely
this will translate to slightly increased rain chances this
weekend before dry air returns next week. Given the inherent
uncertainty in predicting these spells of moisture and dry air
several days out, chance pops will be kept in the forecast from
Saturday through the forecast period. 


Light to gentle east to southeast breezes will continue overnight
and Wednesday. Thunderstorms coverage will be isolated at best,
and skies should be mostly clear through this periods. On
Wednesday night winds will pick up a few knots, with gentle to
moderate breezes over the Keys coastal waters.


VFR conditions will prevail at both the Key West and Marathon
terminals through this evening and into Wednesday morning. Near
surface winds will be mainly out of east to east southeast near 10


Key West  83  90  83  90 / 20 20 20 20 
Marathon  84  92  84  91 / 20 20 20 20 




Data Collection......BT

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