Area Forecast Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS62 KKEY 231326

Area Forecast Discussion
National Weather Service Key West FL
926 AM EDT Mon Oct 23 2017

.DISCUSSION...In the middle and upper levels(700-200 mb), latest
available satelitte imagery overlaid with model streamline
analysis as of 900 am depict the main axis of a narrow full
latitudinal ridge positioned from Central Quebec south to Cuba,
migrating eastward. Just downstream of that is a still amplifying
polar trough with main axis from Manitoba down to the Western Gulf
of Mexico, with some semblance of a 500 mb low trying to pinch
off near the Mid-Mississippi Valley. South Florida and the Keys
still remain beneath periphery of the middle and upper ridging
attm, but mid level heights are falling to the immediate west over
the Eastern Gulf.

At the surface and in the lower to middle levels, (Surface to 700
mb), latest available satelitte imagery overlaid with marine and
land surface observations and analysis as of 900 am detail the
center of a strong autumnal high over the NW Atlantic just
offshore of Nova Scotia. West of that, a significant cold front is
draped from Western Quebec down into the South Central Gulf of
Mexico at 90 West thence into the Bay of Campeche. As a result,
the 12Z morning at Key West illustrated a moderate to occasionally
fresh southeast flow from off the surface to about 700 mb,
becoming gentle south and veering to west and increasing above
500 mb, with total columnar PWAT still at 1.99 inches.

.CURRENTLY...As of 900 am, skies are partly cloudy across the
islands and all surrounding waters, with radar detecting isolated
to widely scattered low topped showers positioned from the
Upper/Middle Keys south southeast into the Florida Straits out 60
nm. Temperatures over the islands are in the lower 80s with
dewpoints in the lower to mid 70s. C-man stations along the
Florida Reef are recording southeast winds near 15 knots except
15 to 20 knots off of the Upper Keys. Island platforms are near 15

.SHORT TERM...Rest of the day and this evening, The center of the
strong surface high over the NW Atlantic will quickly east by
days end, as energy in the middle and upper trough begins to
carve it out more as it migrates towards the Eastern Seaboard and
Florida. The surface front moves slowly from the Central towards
the Eastern Gulf of Mexico by this evening. The net result of this
is that winds will subside markedly throughout the day. As such,
the latest available ECMWF, and GFS forecast soundings illustrate
that the lower to middle levels remain fairly moist all in all
with PWAT remaining between 1.75-2.00 inches, but there exists a
patch of drier air between 800 and 650 mb, and given a lighter
veering low to middle level confluent flow, am tempted to take
pops down to isolated...20%...for the rest of the day.

Then this evening and overnight, mid to upper level
destabilization as well as low to middle level moisture will allow
for better confluence ahead of the approaching cold front,
probably allowing Cuban boundaries to move towards the Keys, so
the middle of the road chance...40%..pops seems on track.


.MARINE...This afternoon and evening, will be dropping the SCEC
headlines for the Hawk Channel and may drop it for the Straits
pending an avail ASCAT pass. Winds and seas will let down a bit
more this evening, but an increase in showers and some
thunderstorms is anticipated ahead of the cold front over the




Upper Air/Data Collection......11

Visit us on the web at

Follow us on Facebook and Twitter at: is the U.S. government's official web portal to all federal, state and local government web resources and services.