Area Forecast Discussion
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FXUS62 KKEY 170852

Area Forecast Discussion
National Weather Service Key West FL
452 AM EDT Tue Oct 17 2017

A weak pressure pattern persists across the Florida Keys and
adjacent coastal waters this morning. Breezes are either variable
or blowing out of the northeast or east near 5 knots or less. Some
island interior stations are reporting calm conditions. A cold
front has advanced to the northern Gulf of Mexico and northern
Florida. The associated mid-tropospheric short-wave trough has
induced geopotential height falls and deep cyclonic flow across
much of the Gulf of Mexico, along with strengthening westerlies
aloft. A very light east-northeast low-level flow prevails across
the Florida Keys this morning, with maritime tropical air
persisting at the surface, and contributing to a moderately
unstable atmosphere supportive of isolated rain showers. Current
air temperatures in Keys island communities range from near 75F in
island interior locations to near 80F by the water. Coverage of
slow-moving showers has been isolated, with no thunderstorms

Cloud cover and rain chances should increase some after midday as
weak large-scale ascent associated with the advancing large-
scale trough further destabilizes and moistens the local
atmosphere. The trough and associated force fields will diminish
with decreasing latitude, and low-level momentum will remain weak.
Therefore, our forecast rain chances are lower than the model
consensus for tonight-Wednesday night. Thereafter, a trailing
short-wave ridge will fortify a low-level continental polar
anticyclone over the southeastern United States. This system will
move eastward, and lead to freshening northeast to east breezes
locally. However, the wind surge does not look like it will be as
robust or long-lived as previously thought. Nevertheless, the
increased upward fluxes of heat/moisture into a turbulent boundary
layer will ensure that shower coverage remains above average
through the end of the week.

No watches, warnings, or advisories are in effect. A weak
pressure pattern will persist across Florida Keys coastal waters
this morning, with resulting light or gentle breezes prevailing. A
high pressure system will build gradually across the southeastern
United States and adjacent coastal waters this week. As a result,
northeast to east breezes will freshen slowly across Keys coastal
waters, from Wednesday through Saturday.

VFR conditions are expected to prevail today at both terminals, with
winds generally from the NE to ENE at 5 to 10 knots.

On this date in 1910, a severe, slow-moving October hurricane
battered the lower Florida Keys, bringing storm surge flooding to
the community of Key West that was worse than that observed during
Hurricane Wilma in 2005.

Key West  87  77  86  77 / 30 50 50 40
Marathon  89  77  86  77 / 30 50 50 40




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