Area Forecast Discussion
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FXUS62 KKEY 030953
AFDKEY

Area Forecast Discussion
National Weather Service Key West FL
453 AM EST Sat Dec 3 2016

.DISCUSSION...High pressure has spilled southeast into the Ohio River
Valley, bulging beneath a deep mid-upper level ridge anchored in the
Western Caribbean. Water vapor imagery highlights the vast expanse of
dry air associated with the ridge complex. And yet, a thin ribbon of
moisture associated with yesterday`s denigrated front lies across the
Keys (see MIMIC TPW). This area of weak moisture convergence
continues to produce isolated showers based upon the latest KBYX
radar loops. Temperatures are in the mid to upper 70s across the
island chain, with dewpoints a few ticks below. Based on the southern
Florida METARS, there is a significant dewpoint gradient north of the
FLorida Keys--KAPF reading 53 degrees. Skies have been mostly
cloudy.

.FORECAST...Pressures will rise across the Florida Keys this morning,
heralding a slightly drier airmass (dewpoints around 70) and
freshening northeast to east breezes. Most marine locations should
reach 20 knots around 15Z this morning. The cooler waters bay and
gulf side of the middle and upper Keys will increase just past 15
knots. Anchored by a nearly stationary mid- upper level ridge across
the Western Caribbean, ridging will fan eastward into the eastern
United States, today through Monday. Fresh northeast breezes will
gradually become southeasterly as the surface high slides east with
the upper level ridging. The southerly moisture tap will return by
Monday or Tuesday, in response to the next storm system racing
northeast through the Mississippi River Valley. This storm system
will orphan a front over the Gulf of Mexico and the Florida
Peninsula, eventually eroding into a surface trough. The broad and
lingering trough will prevent the subtropical high from making
progress back to the west. Thus, deep ridging will hold slight rain
chances through Monday. Rain chances will climb to 30 percent Tuesday
and Tuesday night, and may need to be nudged upward Wednesday and
Thursday. Through most of the short term, temperatures will be
slightly above normal, with stubborn dewpoints climbing back into the
mid 70s. A vigorous cold front will race across the Gulf of Mexico
Wednesday night or Thursday, pushing through the Keys by Friday.

&&

.MARINE...Small Craft Advisories in effect for most of the coastal
waters of the Florida Keys, the only exclusions are bayside and gulf
side of the middle Keys and Florida Bay. From synopsis, high
pressure currently centered over the east- central United States will
expand across the western north Atlantic as it works eastward today
through Monday night. A trough of low pressure over the northern Gulf
of Mexico will move east across the Florida peninsula Tuesday and
Tuesday night. A weak pressure pattern will prevail Wednesday and
Wednesday night. Thus...fresh northeast breezes today will slowly
become southeasterly by Monday night...then gradually diminish
Tuesday through Wednesday night.

&&

.AVIATION...A broken swath of clouds based between 1000 and 1600 ft
lingers near the island chain. As a result, periodic rounds of MVFR
ceilings can be expected at the island terminals. In addition, a few
showers embedded within this swath of clouds may produce a round or
two of MVFR/IFR visibility due to moderate to heavy rain. Ceilings
are expected to gradually lift and rain chances diminish through the
day. They may mix and scatter out as winds gradually increase to 10
to 15 knots with gusts near 20 knots.

&&

.CLIMATE...December 3rd, on this date in Key West Climate history,
in 1876, the daily record low temperature of 45F was recorded.
Temperature records in Key West date back to 1872.

&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...Small Craft Advisory until 4 PM EST this afternoon for
     GMZ033>035-042>044-052>055-072>075.

&&

$$

Public/Marine/Fire/Climate...CLR
Aviation/Nowcasts....11
Data Collection......Fling

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