Area Forecast Discussion
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FXUS62 KKEY 241858

Area Forecast Discussion
National Weather Service Key West FL
258 PM EDT Sat Jun 24 2017

A corridor of isolated rain showers has shifted slightly westward
during the day, and currently runs from about the Cay Sal Bank to
Key West and vicinity, according to recent Doppler radar base
reflectivity scans. In fact, we just observed a brief downpour and
a wind gust to 25 knots here at the forecast office in mid-town
Key West. Prior to the rain shower, the air temperature was near
90F, as it currently is in most Keys island communities early this
afternoon. Dewpoint temperatures are in the mid to upper 70s, with
heat indices of 100-105F at most locations.

The large-scale pattern features a deep layer mean anticyclone
centered over the western North Atlantic. The Florida Keys are
positioned beneath the southwestern flank of this system, beneath
a deep, meandering easterly current, along with synoptic-scale
subsidence. A ridge extends westward from the anticyclone center
to the southeastern United States. Over the next week, the ridge
will move southward, then northward again, as a midlatitude trough
migrates across the eastern continental United States. The effect
of this evolution in the Keys will be lighter and more variable
winds in the lower troposphere during the Monday-Wednesday time
frame, before a steadier and fresher east-southeast breeze
develops again Thursday through Saturday. Rainfall coverage will
persist below average through Sunday, with little chance for
thunder/lightning, as a plume of low-level dry moves through the
service area. Arrival of a deeper moist layer on Monday will
support slightly higher rain chances. Thereafter, the moist layer
will undergo periodic increases and decreases in depth as minor
perturbations in the easterlies move through, supporting a uniform
near-climatological rain/thunder chance. &&

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

VFR conditions will continue tonight for both EYW and MTH terminals
with southeast winds near 10 knots.

Key West  82  89  82  89 / 10 10 20 30
Marathon  82  91  82  91 / 10 10 20 30



Data Collection......Chesser

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