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Area Forecast Discussion (AFD)

Issued by Key West, FL (KEY)

FXUS62 KKEY 201953

Area Forecast Discussion
National Weather Service Key West FL
253 PM EST Tue Feb 20 2018

Currently - A large high extends from the North Atlantic and across
the southeastern United and Gulf of Mexico. This is resulting in
moderate to fresh east to southeast breezes across the Florida
Keys. Despite healthy deep layered ridging, there is enough flux
and and a deep enough mixed layer to support isolated fast moving
showers. Only a few island locations have been briefly affected by
these passing showers. The south of east trajectory has brought in
increased moisture, and dew points are sitting in the lower 70s.
Temperatures were able to edge to near 80 degrees, with some
locations pushing a bit higher.

Forecast - The large surface high will remain fairly static for
the remainder of the week. This will maintain nearly steady state
conditions, breezy with highs 80 to 85 and overnight lows in the 
lower to mid 70s. Rain chances are expected to slip below 10 
percent tonight as forecast soundings indicate the inversion 
shifting 75 mb lower. This appears to be the case as upstream, 
there is less vertical development in the cloud field and AMX 
radar indicates zero shower activity up stream. Rain chances will
edge upwards later in the week as the a broad inverted trough
rides in on the southern periphery of the ridge. In addition, the
inversion will ascend and weaken, providing enough head room for 
isolated to scattered shower formation.

The high to our north is expected to shift southwards and retreat
eastwards into the Atlantic late in the weekend. As a result,
winds will slacken and turn more southeasterly. The lower level
flow will become less organized and will reduce convective
forcing. Consequently, will maintain only slight pops.


A strong ridge across the southeastern United States will result
in fresh east to southeast breezes across much of Florida Keys
waters. A small craft advisory remains in effect for Hawk Channel
and Florida Straits. Cooler shelf water will keep advisories out 
of the gulf waters. Effects of South Florida has been also keeping
the Florida Bay a bit weaker. Winds will will finally trend 
downwards beginning Friday as the ridge begins to shift 


VFR cigs and/or vis will prevail tonight at both the KEYW and 
KMTH Int'l island terminals. Expect fairly uniform east- 
southeasterly winds sustained near 15 knots, with occasional gusts
near 25 knots through the terminal forecast period.


On this date in Keys weather history, in 2015, a low temperature of 
49 degrees was recorded in Key West. This set the daily record for 
coldest temperature for February 20th, and this record will likely 
stand another year, as lows will likely stay in the mid 70s this 
morning. Temperature records for Key West date back to 1872. 


Key West  75  81  73  81 / -  -  20 30 
Marathon  76  83  74  83 / -  -  20 30 


GM...Small Craft Advisory GMZ042>044-052>055-072>075.



Data Collection......Chesser

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