Area Forecast Discussion
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FXUS62 KKEY 290749

Area Forecast Discussion
National Weather Service Key West FL
349 AM EDT SUN MAY 29 2016

.DISCUSSION...In the middle and upper levels, (700-200 MB), the
latest available IR imagery overlaid with model streamline analysis
as of 2 am, like 24 hours prior, details the axis of a negatively
tilted warm core middle and upper level ridge situated from New York
State south southeastwards to around 30 North and 69 West, and west
of that feature is an upper trough axis that extends from the Mid-
Mississippi Valley southeast to down the Florida Peninsula to the
Central Bahamas.

At the surface and in the lower to middle levels, (Surface to 700
MB), the center of Tropical Storm Bonnie, at 200 am EDT, was located
about 155 south of Myrtle Beach and moving north near 6 mph. This is
trailing a surface trough back towards the Keys, resulting in a col
across much of the islands and immediate adjoining waters.

.CURRENTLY...As of 2 am, skies are mostly clear across the islands
and adjoining waters. Radar detects one or two light showers in the
far Southwestern Florida Straits. Temperatures across the island
chain are in the Upper 70s to near 80 with dewpoints around 70. C-man
stations along the Florida Reef are recording East to southeast winds
at 5 to 10 knots, with mostly northeast to east winds near 5 mph over
the islands.

.SHORT TERM...Today through Tuesday, the continuation of light winds,
typically high humidity, and low chances for showers will make the
holiday weekend uncomfortable for those of us not on a boat or in
the waters. A weak pressure pattern will cause winds to be variable
today thru Monday Night, as Tropical Storm Bonnie moves inland over
the Carolinas, then exiting the North Carolina Coast by Monday Night.
Weak ridging will begin to build in across South Florida on Tuesday.
In terms of expected local mesoscale impacts and rain chances, only
very slight chances for showers and thunderstorms, 10% is expected
today through Monday night and Memorial Day. Any cloudlines that
develop will be vertically challenged on account of middle level dry
air. Forecast soundings illustrate PWAT averaging between 1.25 and
1.50 inches in the column and with only a A Slight 0-6 km storm
motion from the mainland will be questionable for any boundaries to
leak into the Upper Keys as well. For Monday night and Tuesday, a
slightly deeper northeast to east flow from the surface to 800 or 700
mb is indicated, but PWAT still remains between 1.25 and 1.50, so
will maintain only 20% pops for showers.


.LONG TERM...Tuesday night thru Saturday, Surface Ridging across the
Florida Peninsula is weak for the Tuesday night through Wednesday
night periods and given an increase in moisture in the lower to
middle levels, will be maintaining just isolated pops in the grids for
these three periods, but then during Thursday, another large
(synoptic) scale low amplitude middle level trough at 500 mb
presently over Texas and the Western Gulf of Mexico, will begin to
migrate towards South Florida and the Keys. This will result in
additional middle level cooling and additional destabilization (at
500 mb), and given the lighter surface ridging to the immediate
north, this scenario is more supportive of cumulus/towering cumulus
cloud line genesis. And at this time we are carrying 30% pops for
low chances for showers for Thursday through Saturday. However, if
forecast soundings illustrate additional columnar moisture than is
depicted now, than these numbers may be to conservative, and after
all, it is the beginning of the wet season.


.MARINE...No headlines or advisories foreseen today through next
week, however, cumulus cloud lines will be possible near the Keys
through the rest of the weekend and much of next week, so mariners
should be on the lookout for waterspouts, which tend to form along
the edges of long, dark, flat cloud bases and are dangerous to
boaters as they can easily flip them over resulting in drowning. If
you see one, move away from it ASAP at a 90 degree angle. Light to
gentle winds will continue until tuesday, with gentle to moderate
breezes by tuesday night though late in the week.


Until 00z/30th, expect VFR conditions at the EYW and MTH terminals
with variable to mostly east winds of less than 10 knots.


In 1926, the daily record low temperature of 68 degrees was
recorded in Key West. Temperature records have been kept since


Key West  86  77  86  77 / 10 10 10 20
Marathon  88  78  88  79 / 10 10 10 20





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