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Area Forecast Discussion (AFD)

Issued by Key West, FL (KEY)

FXUS62 KKEY 141459

Area Forecast Discussion
National Weather Service Key West FL
959 AM EST Wed Nov 14 2018

.DISCUSSION...In the middle and upper levels( 700-200 mb), latest
available GOES-R satellite imagery overlaid with model streamline
analysis as of 1000 am indicates an exceptionally deep full
latitudinal longwave pattern for the middle of November, with an
embedded powerful middle level cyclone at 500 mb developing over 
the Southern Plains. This system is trailing an attendant 
northeast to southwest oriented trough axis, which extends down 
to west of the Central Mexican Pacific Coast. Conversely and 
downstream of that, ridging is evident with the axis of the ridge 
positioned from the Middle Ohio Valley south southeast to Cuba, 
however, the aforementioned middle low is beginning to erode the 
Northern extent of the ridging. 

At the surface and in the lower to mid levels(Surface to 700 mb),
latest available GOES-R satellite imagery overlaid with marine 
and land surface observations and surface analysis, as of 900 am,
detail a powerful attendant cold front extending south southwest
wards to across Central Florida thence to the Western Yucatan 
Peninsula from a deepening low pressure system near Prince Edward
Island. As such the 12Z sounding at Key West illustrated a
moistening and veering southeast lower to mid level profile,
surface to 750 mb, then becoming southwest above that up to 200

.CURRENTLY...As of 1000 am, skies are mostly sunny across the
islands and surrounding waters across the islands and surrounding
waters. with only a few showers and a thunderstorm or two located
across the Northwestern Offshore Gulf waters. Temperatures across
the islands are already in the lower to mid 80s, on there way to
record upper 80s, with dewpoints in the ridiculous mid to upper
70s. C-man stations along the Reef are east to southeast near 10

.SHORT TERM...The cold front will begin to move thru the afternoon
and this evening as it approaches the Keys. Gentle southeast or
southeast to south winds will slacken off this evening. The short
term models, like the HRRR are indicating that some pre-frontal
activity, i.e fast moving showers with embedded storms may move 
from west to east across the waters this evening. Will be
monitoring this trend through the afternoon. As just mentioned,
this will be a record breaking warm day, with temps hitting the hi
80s. Minor updated already made thru the afternoon for pops and 
wind direction.


.MARINE...Will be watching a possible prefrontal boundary of
showers with embedded storms for this evening. My need to issue
some SMWs if it gets going. Thereafter, a cold front stalled over
the Gulf of Mexico will surge towards the Florida Keys tonight, 
then blast southeast through the island chain Thursday. Strong 
northerly breezes and building seas are expected behind the front,
and Small Craft Advisory conditions are expected Thursday and 
Thursday night. Breezes will diminish on Friday, followed by 
several days of moderate northeast to east breezes. 


VFR conditions are expected to prevail at both KEYW and KMTH through 
the forecast period. Winds will generally be from the east-southeast 
below 10 knots. Scattered showers and isolated thunderstorms will 
approach the Lower Keys late tonight, potentially bringing MVFR 
conditions to KEYW after 06z along with a shift to westerly winds. 




Upper Air/Data Collection......BT

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