Area Forecast Discussion
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FXUS62 KKEY 241448

Area Forecast Discussion
National Weather Service Key West FL
1048 AM EDT Sat Jun 24 2017

Data from the Key West morning radiosonde balloon indicated a
shallow moist layer, weak conditional instability, and strong
convective inhibition. Dry air extended to low altitudes, with
a dewpoint depression of 6C even at 925mb. Despite the unfavorable
prospect for cumulus convection which this analysis implies, an
appraisal of base reflectivity data from the Key West Doppler
Radar over the last several hours shows widely scattered rain
showers developing mainly within a 75-mile corridor from the Cay
Sal Bank to the extreme southeastern Gulf of Mexico off Mainland
Monroe County. In any case, most of these showers are associated
with cumulus congestus less than 15000 feet tall, suggestive of
weak, short-lived updrafts.

Currently, air temperatures in most Keys island communities are
rising slowly through the mid to upper 80s, with dewpoint
temperatures in the mid 70s. Heat indices already are approaching
100F in many locations. A steady southeast breeze persists,
averaging 10-15 mph over land, and ranging from 10-15 knots to
15-20 knots over water, with the higher wind speeds, south of the
Florida Reef tract.

On the large scale, a deep layer mean anticyclone is centered over
the western North Atlantic this morning. The Florida Keys and
adjacent coastal waters are positioned beneath the southwestern
flank of this anticyclone, with a prevailing deep current of
east-southeast winds.

The current forecasts are sound, and will remain valid through
1800 EDT. Upshot -- Average temperatures and sky cover, above
average wind speeds, and below average rain chances.

Small Craft Should Exercise Caution in the Straits of Florida
this afternoon. A high pressure system centered over the western
North Atlantic will govern the weather pattern across the Florida
Keys and adjacent coastal waters, from this afternoon through

VFR conditions are expected to prevail this afternoon and tonight
for both terminals with southeast winds of near 10 knots.



Data Collection......Chesser

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