Area Forecast Discussion
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FXUS62 KKEY 291935

Area Forecast Discussion
National Weather Service Key West FL
335 PM EDT MON AUG 29 2016

.DISCUSSION...In the middle and upper levels(700-200 mb)...latest
available satellite imagery overlaid with model streamline analysis
as of 200 pm continues to depict a poorly aligned middle and upper
trough over the NW Gulf of Mexico. Well east of that, the center of a
slowly stretching TUTT (Tropical Upper Tropospheric Trough) cell was
located at about 32 North 80 West. Between these two features, there
is weak ridging just north of the developing tropical cyclone TD #9.
Lastly, the western periphery of a deep and warm middle and upper
anticyclone centered on the Mexican Coast is reaching to near 24
North 90 West in the Central Gulf of Mexico.

At the surface and in the lower to middle levels (Surface to 700
mb), latest available marine and land surface observations and
analysis as of 200 pm detail the strongest surface ridging, or near
1022 to 1025 mb surface ridge located from the St Lawrence Valley to
Chicago. To the south of that, the center of TD #8 is located 160miles
SE of Cape Hatteras NC at 800 am. But closer to the Keys, as of 11 am,
the center of TD# 9 was at 23.6 North, 84.3 West and moving at 280degrees
near 7 mph, which continues to pull away from the NW Cuban coast.

.CURRENTLY...As of 200 pm, skies are partly to mostly cloudy across
the islands and adjoining waters. Key West radar has been indicating
that most of the showers within rainbands have impacted the Upper
and Middle Florida Keys. Temperatures across the islands outside of
convection are in the Upper 80s across the islands with dewpoints in
the upper 70s. Surface winds across the islands range from only 10 to
15 mph across the Middle and Upper Keys to 15 to 20 mph across the
Lower Keys.

.SHORT TERM...Tonight thru Thursday Night, TD #9 continues to
organize across the SE Gulf of Mexico, but is progged to be low per
NHC due to factors relative to dry air and shear. AS such, locally,
confluent rain bands will continue to develop into the tropical
cyclone and these will deliver fast moving showers northwards across
the Florida Keys through midweek. This is of course predicated on a
official NHC track of this tropical system more to the NW thence
northward, and finally northeastward across the Northern Florida
Peninsula and/or the Panhandle. This should result in breezy to
windy conditions across all of the islands and surround waters, with
peaks and lulls in the winds, especially with lulling more likely
across the Upper Florida Keys and surrounding waters, which are
downwind of the blocking influence of the Florida Peninsula.

Rain chances will be in the likely category through at least
tomorrow afternoon, with high chances in the grids through Wednesday.
Rainfall amounts are in agreement with neighboring office with some
minor tweaking on the border. Given the location of the tropical
cyclone well west of the Keys, there is a substantial MSLP gradient
across the service area which could result in varying windspeeds
across the service area through late week. Therefore will separate
out the Upper Florida Keys land zones from the Lower and Middle
Florida Keys zones. Rain chances will return to near normal Wednesday
night through Thursday Night, but this may be conservative if
confluent banding sends cuban outflow northwards across the Keys late
east afternoon and evening, with boundaries lurking around overnight
and deep tropical moisture remaining in place. Gentle to moderate
breezes will remain uncomfortable by Wednesday night through Thursday


.LONG TERM...Friday through Labor Day, a weaker typical ridge is
progged to build north of the islands for this time, resulting in
return to more of a gentle east wind across the islands. Temperatures
and humidity will be seasonably uncomfortable. For now, am carrying
low chance pops, given typical mesoscale influences, but a more ideal
wind profile will result in higher chances for showers and
thunderstorms. Also keep in mind that we are approaching the
climatological peak in the tropical atlantic, Sept 10th and models
are actually attempting to bring something across beyond day 7 and
have been consistent on the account of decent ridging blocking a
westward moving tropical system. Just something to file in the back
of your minds attm.


.MARINE... A separation is also necessary in the marine zones to
account for the aforementioned lulling, where we have cautions
statements for tonight across the Florida Bay, Hawk Channel waters
adjoining the Upper Keys, and the Atlantic waters out 60 nm from the
Reef between Ocean Reef and Craig Key. Small craft advisories will be
required at least tonight and likely tomorrow and tomorrow night
across all waters west of that demarcation. Winds and Seas will let
down a bit on Wednesday for all waters on either side of the island
chain, with all headlines or advisories likely gone for Thursday


.AVIATION...Tropical Depression Nine will continue to move farther
away from the Florida Keys this afternoon and tonight. Brief (30
minutes or less), IFR visibilities are likely at EYW and MTH from
time to time this afternoon and tonight due to passing showers.
Sustained southeast to south winds of 20 to 25 knots expected from
just off the surface to about 5,000 feet.


On this date in Florida Keys weather history, in 1889, the low
temperature in Key West was 70 degrees. This set the daily record
for minimum temperature measured in Key West on August 29th, a
record which still stands 127 years later. Rainfall records at Key
West date back to 1871.


Key West  78  85  79  87 / 70 70 50 50
Marathon  78  87  79  88 / 70 70 50 50


.KEY Watches/Warnings/Advisories...
GM...Small Craft Advisory tonight for GMZ032>035-043-



Data Collection......Vickery

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