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Area Forecast Discussion
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FXUS62 KKEY 230947
AFDKEY

Area Forecast Discussion
National Weather Service Key West FL
447 AM EST Wed Jan 23 2019

.DISCUSSION...
.CURRENTLY...
Under partly to mostly cloudy skies and east to southeast winds of
15 to 25 mph with occasional gusts to near 30 mph, temperatures
range from 70 to 75 degrees along the island chain.
Meanwhile, local radars are detecting widely scattered showers on
the waters from 10 to 60 nm south of Cosgrove Shoal Light to
beyond Dry tortugas. Elsewhere, isolated small showers have been
racing northwestward across the Lower keys and the adjacent Gulf
and Atlantic waters, but with little if any measurable rainfall.
Surface wise, a very formidable and expansive area of high
pressure is anchored along the entire Eastern Seaboard and down
the Florida Peninsula and into the Eastern Gulf of Mexico. Due to
a very tight pressure gradient, winds are east ranging from 20
knots at Long Key Light and Smith Shoal Light to 26 knots with
gusts near 30 knots at both Molasses Reef and Alligator Reef
Light.

&&

.SHORT TERM...(Today through Friday night)
A highly amplified pattern will prevail over the next several
days, as an extremely deep trough over the nations midsection
equatorward to Old Mexico drives eastward through tonight, before
slowly lifting northward especially in the mid and upper levels
above 700 mb. Because of the transitory trough aloft, the hefty
Western Atlantic Anticyclone anchored along the Eastern Seaboard
and the Sunshine State will be shoved into the Atlantic Ocean on
Thursday. Subsequently, a predominate anticyclonic flow which has
been dominating our sensible weather elements will become a deep
cyclonic flow by Thursday morning. With that, a cold front will
migrate through the Gulf of Mexico and slide slowly across our
entire region Thursday afternoon and Thursday evening. Given
modest low level confluence and some mid left ascent, see no
reason to stray from categorical pops for Thursday, before some drier
and cooler air filters in Thursday night. For the end of this
week, the frontal boundary should get pushed into the Bahamian
chain and across the island of Cuba, so only low chance pops seem
reasonable for this time frame. But until then, only isolated pops
will be kept today through most of tonight. Temperatures will
remain about 5 degrees above normal through Thursday, before
below normal temperatures return Thursday night through Friday
night.

&&

.LONG TERM...(Saturday through Tuesday)
As mentioned yesterday, considerable uncertainty including timing
of a cold front draped across the archipelago of Cuba lifting
back northward, as a southern stream short wave trough combined
with the right entrance region of the jet stream migrates eastward
through the Gulf of Mexico and across the Sunshine State. Pending
on the timing and the amplitude of the flow aloft will determine
when, the extent and intensity of possible rainfall moving into
our entire region. Current thinking is despite changeable skies
and slightly below normal temperatures, the frontal boundary will
remain south of the Florida Keys for most of this weekend. With
that, have raised pops into the chance category for Sunday night
through Monday night, with a slight chance thereafter. However,
given the complexity of this overall pattern, please stay tuned
because changes are likely to be made to the current forecast.

&&

.MARINE...
Strong east to southeast winds will persist on most Keys coastal
waters today and this evening, before slackening tonight and on
Thursday. Hence, a Small Craft Advisory will likely remain in
effect for our entire marine district today and this evening,
before the aforementioned gradual abatement tonight and on
Thursday. Meanwhile, a cold front is expected to move across our
region on Thursday and clear our entire area late Thursday
evening, followed by freshening north to northeast winds into
Friday. In addition, isolated thunderstorms are likely to be occur
within the frontal boundary.

&&

.AVIATION...
VFR conditions are expected to prevail at the Key West and Marathon
terminals with occasional ceilings above MVFR criteria, near 040-
060. Vicinity showers are possible early as well. Gusty easterly
winds will veer southeasterly and weaken a bit today.

&&

.CLIMATE...
In 1983, the daily record rainfall of 5.69 inches was recorded in
Key West. Temperature records date back to 1871.

&&

.PRELIMINARY POINT TEMPS/POPS...
Key West 80 72 78 63 / 10 30 80 50
Marathon 83 73 80 61 / 10 30 80 50

&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...Small Craft Advisory GMZ031-032-34-035-042>044-052>055-072>075.

&&

$$

Public/Marine/Fire...APA
Aviation/Nowcasts....WLC
Data Collection......SD

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