Area Forecast Discussion
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FXUS62 KKEY 211422

Area Forecast Discussion
National Weather Service Key West FL
1022 AM EDT Sat Apr 21 2018

Mostly sunny skies are present across the island chain and
temperatures are already in the upper 70s and low 80s. Dew points
are in the upper 60s to low 70s and winds are easterly, on
average, near 10 mph across the island chain and nearshore
waters. High pressure is centered in the northeastern US. MIMIC
imagery indicates a dry low-level atmosphere surrounding much of
the Florida Peninsula, though a plume of moisture is drifting
westward between Central Cuba and the western Bahamas.

The 12z KEY sounding revealed instability near 800 j/kg, a PWAT
near 1.1 inches, but a very weak wind profile, with less than 20
knots of shear up to 6 km. The upper atmosphere was quite dry from
800-500 mb.

As the surface anticyclone shifts into the northwestern Atlantic,
the local pressure gradient will tighten out of the northeast,
bringing moderate breezes later this afternoon and overnight.
Conditions will become gradually more favorable for shower
development overnight as low level moisture increases under
accelerating flow, though model agreement is rather low of the
scenario tonight, especially considering the short time frame. The
eastern Straits and Upper Keys seem to have the best shot of
receiving showers overnight (where the best moisture and low
level wind fields meet), but will hold off on an update until the
major model guidance comes in, due to the low confidence of the
scenario. Expect another warm day with highs in the mid 80s.


No watches, warnings, or advisories are in place for the Florida
Keys today. Small craft may need to exercise caution in the
Florida Straits tonight for increasing winds. An expansive area
of high pressure covering the entire Eastern United States will
slide into the western North Atlantic Ocean over the next several
days, as a weak area of low pressure migrates eastward and across
the Southeast United States before lifting up the Eastern Seaboard
next week.


Rest of today, VFR conditions will prevail at EYW and MTH. A few
clouds will be found aoa FL020-025 with just some cirrus above that.
Surface winds will average 5-7 knots from 060-100 degrees.


Key West  85  78  84  78 / 0 10 20 20
Marathon  86  78  86  78 / 0 10 20 20




Data Collection......DAF

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