Area Forecast Discussion
Issued by NWS
FXUS62 KKEY 102019
Area Forecast Discussion
National Weather Service Key West FL
319 PM EST Sat Dec 10 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 an expansive broad low amplitude long wave polar
trough presently encompassing the entire CONUS. Well to the south of
that, the main axis of a deep and warm anticyclone is positioned
across the North Central Caribbean Sea, or just to the south of
Puerto Rico to Jamaica.
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
near 1040 mb arctic surface high pressure located over Central
Kentucky. Well to the south of that, a stationary boundary remains
draped from the NW Bahamas to Pinar Del Rio Cuba.
.CURRENTLY...As of 200 pm, skies are mostly cloudy across all of the
Keys and surrounding waters. Radar thus far today continues to
detect boundary of moderate to locally heavy showers migrating
slowly westwards through the Eastern Florida Straits towards the
entire Florida Keys Island Chain. Temperatures across the islands
have reached the upper 70s to around 80 degrees with dewpoints in the
upper 60s. C-man stations along the Florida Reef are northeast
registering 15 to 20 knots and gusty, except near 15 knots in Florida
Bay, but near 20 knots at Smith Shoal Light and from Sand Key
westwards to Pulaski Shoal Light.
.SHORT TERM...Tonight through Monday night. A windy and abnormally
wetter pattern will impact the Florida Keys for the next two periods
to finish out this weekend. This will followed by a return to near
or slightly above normal temperatures for next week with just gentle
breezes and much higher than average humidity expected to return as
the dewpoint climbs back above 70 degrees. The aforementioned near
1040 mb strong surface arctic high over Kentucky will weaken to a
near 1030 mb ridge off of the Mid- Atlantic Coast by daybreak or 12Z
Sunday. This strong ridging in combination with the close proximity
of a frontal boundary accompanied by deepening lower to middle level
moisture with a strong upper jet stream as well as lower level
convergence over the Keys, will allow for a high chance for showers
tonight. A few locations where the best convergence bands set up
could also allow for locally heavy rainfall, as was the case across
South Florida today. Conditions should begin to dry out during Sunday
and breezy conditions will diminish by the end of the day.
Thereafter, the center of a weaker 1025 mb ridge will be positioned
over South Carolina during Sunday night and move south and weaken
further as a ridge across the Florida Peninsula. Since the winds will
favor more east to southeast, elevated temperatures and humidity
will return Monday and Monday Night. Have maintained only isolated
chances for showers Sunday night through Monday Night.
Extended, Tuesday through Saturday, a weaker surface ridge will
remain across Florida through the upcoming week. Forecast soundings
still illustrate slightly elevated moisture remains in the lower to
mid troposphere, so will maintain a decreasing slight chance for
showers as the week goes on, with best chance last at night/early
morning. Temperatures and humidity levels will continue to be several
degrees above normal for daytime highs and overnight lows.
.MARINE...A small craft advisory remains in place for all waters
surrounding the Florida Keys tonight through part of Sunday, except
across the Florida Straits Sunday Night. Winds and seas will let
down markedly thereafter.
.AVIATION...VFR conditions are expected to prevail at the Florida
Keys airports through early evening, with northeast winds 12 to 15
knots and frequent gusts near 20 knots. Rain may reach the vicinity
of Marathon and Key West by late evening, with increasing potential
for MVFR ceilings beginning the 11th 01Z-03Z. Depending on the amount
of rain coverage late tonight across Florida Bay and mainland south
Florida, there is the potential for temporary IFR ceilings during the
early to mid morning hours Sunday.
.PRELIMINARY POINT TEMPS/POPS...
Key West 72 79 75 80 / 50 30 20 20
Marathon 72 79 74 80 / 50 30 20 20
GM...Small Craft Advisory for GMZ031>035- 042>044-052>055-072>075.
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