Area Forecast Discussion
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FXUS62 KKEY 262059

Area Forecast Discussion
National Weather Service Key West FL
359 PM EST Wed Feb 26 2020

Currently - Gentle to moderate breezes are feeding northward into
a prefrontal trough aligned over the Florida Peninsula and the
extreme eastern Gulf of Mexico. Lower level moisture is climbing
due to accelerating warm moist advection. This along with already
little to no inhibition has allowed for the development of large
patches of rain with embedded scattered showers across the Florida
Straits. Some of this activity has periodically crossed over the
island chain. Meanwhile, a robust cold front continues to race
southeastward into the southeastern Gulf of Mexico towards South
Florida and the Keys. Temperatures have pushed near or above 80
degrees with dew points in the mid 70s.

Forecast - The cold front will race southeastward through the
remainder of this afternoon and begin working its way across the
forecast area this evening. Upper level support will largely
remain well north of our area. However, healthy lower level
moist cyclonic confluent flow and cooling profile will continue
to support convective activity this evening. Expect rounds of
showers and possibly a few thunderstorms in advance of this cold
front. Winds will increase sharply as the front pushes through,
becoming quite breezy out of the northwest. This will result in
tapering off shower activity and cooler air will begin to filter
across the area.

The associated long wave trough will park over the eastern United
States through the remainder of the week and into the weekend. The
surface high following behind tonight`s cold front will drive
southeastward into the Gulf of Mexico and stall. A secondary cold
front passage will occur early Saturday, followed by a reinforcing
high pressure system. This will mean quite an extended period of
cool dry conditions along the Keys at least through the weekend.
Temperatures will range about 5 to 10 degrees below normal with
dew points dipping as low as into the 50s. Wind wise, expect
generally northerly flow to freshen and lull as a result of both
the previously mentioned synoptic features, along with day/night
mesoscale effects.

The long wave trough will finally get moving eastward late
Saturday. As a result, the gulf surface high will begin to migrate
eastward across the Florida Peninsula Saturday night and Sunday.
This will gradually nudge the synoptic flow more northeast then
eventually east. After so many days of cool and sometimes fresh
breezes, the nearshore gulf and bay side waters are certain to
cool down considerably. This will act to delay the veering of
winds in the Keys. Winds will eventually push east of of the
island chain sometime early next week, and warming and moistening
will begin in earnest. It won`t take long for temperatures to push
back above normal.


A cold front will race through Keys waters this evening and
tonight. Expect winds to shift northwest and freshen across all
waters. As a result, a Small Craft Advisory will be required for
all Keys waters tonight. A prolonged period of northerly flow is
expected as a high pressure system remains parked in the Gulf of
Mexico. Winds will periodically freshen and lull due to both a
reinforcing cold front and diurnal heating/cooling over the
Florida Peninsula. Winds will finally begin to clock around
towards northeast and eastward through the back of the weekend and
early next week as the high begins to transit eastward across
Florida then into the Atlantic.


VFR conditions will prevail at both terminals through 27/00z.
Passing showers will bring brief MVFR ceilings and/or visibilities,
but prevailing MVFR conditions should wait until frontal showers and
possible thunderstorms develop around 27/02z. Winds will gradually
veer from south to southwest this evening. Winds will abruptly shift
to the west and then northwest while becoming gusty with the passage
of the cold front. A lengthy period of MVFR/IFR ceilings are likely
behind the front, lasting throughout Thursday.


Key West  69  70  57  67 / 80 -  0 -
Marathon  67  71  55  67 / 80 10 0 -


GM...Small Craft Advisory for GMZ031>035-042>044-052>055-072>075.



Data Collection......SDR

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