Area Forecast Discussion
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FXUS62 KKEY 191513

Area Forecast Discussion
National Weather Service Key West FL
1113 AM EDT Mon Mar 19 2018

A scattered deck of clouds (around 2 kft) formed off the warmer
waters of the Straits of Florida (ahead of a land boundary that
pushed off of Cuba) and began moving across the island chain
earlier this morning. This boundary also caused winds to increase
from 5-9am before decreasing around 10am. KBYX detects no precip
echos surrounding the Florida Keys. Morning low temps ranged from
65 in Big Pine Key to 73 in Key Largo. Current temperatures have
since risen to the mid 70s to near 80 degrees, and dew points are
near 70 degrees. The 12z KEY sounding indicated 1200 j/kg of
instability with a PWAT of 1.5 inches. South to southwesterly flow
is in place of near 10 mph across the island chain, and near 10
knots across our marine district.

On the synoptic scale, a frontal boundary is located along North
Florida, and surface high pressure exists in the western Atlantic,
with the mean-layered ridge centered in the Northwest Caribbean. A
cold front is moving through eastern Texas and western Louisiana.

The western ridge axis is expected to move north across the
Florida Keys from 18z-03z this afternoon and evening, leading to
a decrease in the wind field. Forecast soundings indicate mid-
level dry air will begin to filter into the boundary layer as
well, which will contribute to decreasing cloud coverage and near
zero rain chances. As a cold front begins to move across North
Florida late tonight, the pressure gradient will begin to tighten
locally, gradually increasing winds out of the southwest. Minor
tweaks were made to the digital gridded forecast, but overall the
forecast remains on track.


Gentle breezes out of the south to southwest are expected today.
An Atlantic ridge of high pressure will extend across Cuba today
and tonight. A cold front will progress southward down the Florida
peninsula Tuesday. This cold front will pass through the Florida
Keys Tuesday night. An area of high pressure over the Southeastern
United States will build southeastward down the Florida peninsula
Wednesday through Friday.


Until 00z/20th, VFR conditions will prevail at the Key West and
Marathon terminals. Any cloud bases should be near 020. South to
southwest winds of 10 knots or less are anticipated.


In 2013, the daily record rainfall of 1.28 inches was recorded in
Key West. Rainfall records date back to 1871.


Key West  82  75  82  73 / 0 0 10 30
Marathon  85  75  85  72 / 0 0 10 30




Data Collection......APA/MCLOVIN

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