Area Forecast Discussion
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FXUS62 KKEY 170148

Area Forecast Discussion
National Weather Service Key West FL
948 PM EDT Wed Aug 16 2017

A deep layered anticyclone centered over the northeastern Gulf of
Mexico is pushing north into the southeastern United States,
meanwhile a westward moving mid-upper level TUTT axis is nearing
the eastern Bahamas. No wonder this evening`s RAOB analysis
indicates falling heights from 850 through 200 mb in Key West. The
fractured surface ridge axis reaches west across the Florida
Peninsula, supporting gentle northeast to east breezes across the
coastal waters of the Florida Keys. Temperatures are in the mid
80s with dewpoints in the upper 70s. The vertical profile is dry
(see ~1.6"PW 00Z KKEY RAOB), although modified mixed layer parcels
are moderately unstable and weakly inhibited. Satellite derived
PW estimates (around 1.8") indicate a slug of drier air across the
Straits and Florida Keys, in line with the lack of recent shower
activity detected by KBYX radar.

The mysterious dry slug will exit the Florida Keys by sunrise
Thursday. Increased low level moisture combined with deep
northeast to east winds will result in increased rain chances
across the Florida Keys Thursday. The current forecast calls for
30 percent rain chances overnight, with lows between 80 and 85,
and developing moderate east to southeast breezes. No changes
needed or planned.


No current watches, warnings, or advisories. From synopsis, an
Atlantic ridge will extend across Central Florida overnight
through Thursday night. A low pressure system will move into the
eastern Caribbean Sea Friday and Friday night. This low pressure
system will progress westward through the central and western
Caribbean Sea Saturday into early next week, resulting in
freshening east to southeast breezes.


Generally VFR conditions tonight and Thursday morning with only very
isolated showers expected tonight. Moisture levels increase on
Thursday which should result in a much more active day across the
area. Have VCSH in the TAFs beginning 14Z Thursday for both
terminals. Heavier showers or thunderstorms could result in brief
periods of 2-4SM visibilities, broken MVFR ceilings, and wind gusts
to 25 knots Thursday afternoon. Winds will remain less than 10 knots
outside of shower activity. 34/MM




Data Collection......Chesser

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