Area Forecast Discussion
Issued by NWS
FXUS62 KKEY 092006
Area Forecast Discussion
National Weather Service Key West FL
306 PM EST Fri Dec 9 2016
.DISCUSSION...In the middle and upper levels, (700-200 mb), Latest
available IR imagery overlaid with model streamline analysis as of
200 pm continues to depict a rather expansive middle and upper
trough of polar origins positioned across much of the CONUS from the
Rocky Mountains to the Eastern Seaboard. To the south of that, the
main anticyclonic axis of a broad, deep and warm ridge remains positioned
from North of Hispaniola to the Western Caribbean Sea. As such, the
stronger upper jet winds, approximately 125-150 knots at 250 mb are
moving across the Northern Gulf of Mexico NE to the Middle Atlantic
States. An Approximate 50 to 100 knot upper jet is transporting some
cirrus across all of the Florida Peninsula including the Florida
At the surface and in the lower to middle levels, (Surface to 700
mb), latest available IR imagery as of 200 pm, overlaid with marine
and land surface observations and analysis, detail the center of a
1040 mb plus surface arctic high situated over the Ozark Mountains.
Closer to the Keys, a surface frontal is nearly stationary across the
Outer Florida Straits.
.CURRENTLY...As of 200 pm, skies are mostly cloudy across the Keys
island Chain and all surrounding waters. Radar continues to detect
scattered showers south of the Middle Florida Keys along the
aforementioned boundary...with a few heavier showers out at the
Humps. Only chaff covers much of the rest of the maritime real
estate, except a few showers are approaching the Upper Florida Keys.
C-man stations along the Florida Reef are registering northeast winds
between 20 and 25 knots and gusty, as well as near Florida Bay and at
Smith Shoal Light.
.SHORT TERM...Tonight thru Sunday Night, The combination of the
center of arctic high pressure moving slowly eastward towards the
Mid- Atlantic Coast by Sunday and offshore Sunday Night, with a
surface boundary across the Florida Straits, will continue to
generate breezy to windy conditions across all of the islands through
Sunday Night. Indications are that the surface boundary over the
Florida Straits could begin to drag back to the north across the Keys
by tomorrow night and remain in place through Sunday Night.
Confidence is low that this scenario will maintain itself the entire
weekend. As such, we are carrying low chances for showers tonight
through Sunday Night. This is still well above normal for this time
of year, but shown in the GFS forecast soundings, but less so in the
older ECMWF forecast soundings.
Also given the orientations of these surface feature`s, low level
winds will veer more to the east by Saturday Night, allowing low and
high temperatures to rebound to near or slightly above normal levels.
Small Craft Advisory conditions will continue across all of the
waters tonight through at least Sunday, and across portions of the
waters Sunday Night.
.LONG TERM...Monday thru Friday, Latest extended longwave pattern
tends to keep the arctic air across the northern half of the Conus,
with mid and upper ridging over the Southern Gulf and NW Caribbean
having an influence, along with a weak surface ridge across the
immediate north of the Keys over the Florida Peninsula. In this
scenario, elevated moisture and above normal warmth will justify a
slight chance for showers through the entire period.
.MARINE...Small craft advisory conditions are in effect across all
waters tonight through at least Sunday, and portions of the marine
district Sunday Night. Indications are for significant improvement
with better than average boating conditions for the first half of
.AVIATION...Expecting periods of MVFR and potentially IFR ceilings
after 10/01z at both the Key West and Marathon International
Terminals. Cold air running over the warmer waters north of the
Florida Keys will remains saturated above the surface around 1000 to
1500 feet. The cold air over the warmer water will also enhance the
intensity of the winds from the north to northeast today and tonight.
CLIMATE...On this date in Keys Weather History, 1928, the low
temperature in Key West fell to 53 degrees. This set the daily record
minimum temperature for Key West on December 9th, which stands 88
years later. Temperature records for Key West date back to 1872.
.PRELIMINARY POINT TEMPS/POPS...
Key West 70 77 73 79 / 30 30 30 30
Marathon 70 77 72 79 / 30 30 30 30
GM...Small Craft Advisory for GMZ031>035- 042>044-052>055-072>075.
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