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000
FXUS62 KKEY 211853
AFDKEY

Area Forecast Discussion
National Weather Service Key West FL
253 PM EDT Thu Sep 21 2017

.DISCUSSION...
.CURRENTLY...
Outside of pancake type cloud line segments along the island
chain, skies are mostly sunny with temperatures hovering around 90
degrees. Meanwhile, local radars are not detecting any
precipitation echoes in our region. Surface wise, our region lies
on the southern periphery of a continental anticyclone centered
over the southeast United States.

&&

.SHORT TERM...(Tonight through Sunday night)
A complex, but disjointed mid and upper level pattern will slowly
evolve over the southeast United States, eastern Gulf of Mexico
and the Florida peninsula including our region over the next
several days. With that, although an upper level(above 500 mb)
cyclonic flow will be evident, the flow below 700 mb will be
relatively light and chaotic most of the time. So despite
additional moisture, no discernible low level features are
anticipated through the period. Hence, will insert low to medium
range chance pops for the possibility of cells sliding south-
southwestward off the Florida peninsula this evening and tonight.
Thereafter, isolated pops will be retained for Friday with low
chance pops for this upcoming weekend. So in summary, above normal
uncertainty with the discrete possibility of mesoscale forcing in
the form of wet cloud line genesis and cells migrating off our
large surrounding land masses will prompt chance pops.

&&

.LONG TERM...(Monday through Thursday)
Given uncertainty, will retain low chance pops with high
temperatures near 90 and overnight low temperatures near 80
degrees for now.

&&

.MARINE...
Outside of showers and possible thunderstorms migrating south
southwest off the south Florida mainland this afternoon and
evening, light to gentle winds will prevail on Keys coastal waters
for most of the period. However, long period northeast swells of
up to 5 feet are possible on the offshore waters from Ocean reef
to Craig Key. Hence, no exercise caution headlines or advisories
will be needed.

&&

.AVIATION...
VFR conditions will prevail at EYW and MTH through at least the next
24 hours. MVFR ceilings, based at or just below 3,000 feet, are
conceivable at EYW and MTH. This possibility is not great enough to
place in the terminal forecasts at this time. Sustained northeast to
east winds near 10 knots expected from just off the surface to about
3,000 feet.

$$

.CLIMATE...
On this date in Florida Keys weather history, in 1948, a category 3
hurricane made its initial United States landfall near Sugarloaf
Key. The wind speed at Boca Chica reached 122 mph before the
anemometer was blown away. A 5 foot storm tide was observed at
Tavernier. 4.53 inches of rain fell in Key West, setting the daily
record for maximum rainfall measured in Key West on September 21st.
This hurricane occurred before the tradition of naming storms was an
accepted practice.

&&

.PRELIMINARY POINT TEMPS/POPS...
Key West  80  89  80  88 / 30 20 30 30
Marathon  79  92  80  91 / 30 20 30 30

&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...None.
&&

$$

Public/Marine/Fire...APA
Aviation/Nowcasts....BS
Data Collection......DR

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