Area Forecast Discussion
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FXUS62 KKEY 080952

Area Forecast Discussion
National Weather Service Key West FL
452 AM EST Thu Dec 8 2016

Currently, scattered clouds and isolated showers are drifting across
the Florida Keys and adjacent coastal waters.  The air mass remains
warm and muggy, as a stalled and diffuse frontal zone lies just
north of the Keys.  Air temperatures in most Keys island communities
early this morning are in the mid 70s, with dewpoint temperatures
only a few degrees below air temperatures.  An expansive arctic air
mass is plunging southward across the Great Plains and Midwest, and
will approach the northern Gulf coast tonight.  The weather in the
Florida Keys through this weekend will be governed by the evolution
of this fast-evolving arctic air mass and the resulting heat,
moisture, and momentum changes in the lower atmosphere.

The stalled frontal zone just north of the Keys will be "activated"
by the rapid approach of highly modified arctic air from the north
today.  A northerly wind surge will set in from west to east over
the service area from late this afternoon through early Friday.
Winds will veer quickly northeast, with only modest, and short-lived
cold thermal advection peaking Friday afternoon and evening.  In
fact, low-level moisture will remain sufficient for isolated to
scattered rain showers, even after the frontal passage.  Wind speeds,
cloud cover, and rain chances will peak from Saturday afternoon
through early Sunday as a warm front advances northward across the
Florida Keys.  The associated large-scale ascent will be augmented
by robust upward fluxes of heat and moisture, induced by strong and
turbulent low-level flow.  Gradient flow will weaken rapidly Sunday,
with rapidly subsiding winds and seas through Monday.

Small Craft Advisories likely will be required for all marine zones
except Florida Bay tonight.  An arctic air mass will expand southward
across much of the central and eastern United States today.  Ahead of
this system, a weak pressure pattern will persist across the Florida
Keys and adjacent coastal waters this morning.  A cold front likely
will reach the Florida Keys this evening, resulting in strong
northeast to east breezes Friday through Sunday.

A remnant boundary lingering across the island chain may produce
occasional MVFR ceilings late tonight/early Thursday morning, with
the greatest potential 6z-12z. The possibility will also exist
during daytime hours if/when variable flow becomes a northerly, and
increases to a gentle breeze. Otherwise, expect VFR at EYW & MTH.

The high temperature at Key West International Airport yesterday
(7 December) was 85F, tying the previous record of 85F last set in

Key West  80  71  75  68 / 20 30 20 30
Marathon  82  70  75  68 / 20 30 20 30




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