Special Weather Statement, NWS Key West, FL

Area Forecast Discussion
National Weather Service Key West FL
254 PM EDT Sat Aug 19 2017

.DISCUSSION...
.CURRENTLY...
Under partly cloudy skies, temperatures are hovering around 90
degrees along the island chain. Meanwhile, local radars are
detecting isolated showers and an occasional lightning storm on
the nearshore and offshore waters south of the Florida Keys.
Surface wise, a weak ridge lies along the Sunshine State and the
adjacent coastal waters, while a tropical wave is located between
the Bahamas and Andros Island.

&&

.SHORT TERM...(Tonight through Tuesday night)
A tropical wave between Andros Island and the Bahamian chain will
migrate westward and across our region late tonight and Sunday
morning followed by a formidable low level easterly surge into
Monday. Given an increase in both moisture and low level
confluence, shower and thunderstorm activity will be on the
increase especially late tonight and into Sunday. Hence, well
above normal pops will be retained. Thereafter, a freshening and
deepening easterly flow on the southern periphery of an Atlantic
ridge axis to our north will result in middle of the road pops
on Monday. Another tropical wave will approach our area late
Monday night and pass through our region on Tuesday and Tuesday
night. Subsequently, above normal rain chances will be kept for
the first half of next week. Due to additional cloudiness and some
heavy downpours, high temperatures will average from the upper
80s to lower 90s with overnight lows from the mid 70s to the lower
80s.

&&

.LONG TERM...(Wednesday through Saturday)
With the western Atlantic ridge, weakening and sagging southward
from the Florida peninsula and into the Straits of Florida, a
slackening and a predominate southerly flow seems likely. With
plenty of moisture and the light to gentle winds, mesoscale
forcing in the form of wet cloud line genesis and boundaries
emanating off our large surrounding land masses will prompt middle
of the road pops. See no reason to stray from highs in the lower
90s with lows in the lower 80s.

&&

.MARINE...
Outside of showers, thunderstorms and outflow boundaries light to
gentle east winds will slowly increase tonight but especially
Sunday afternoon and night when a Small Craft Advisory/Exercise
Caution headline will likely be needed for most Keys coastal
waters.

&&

.AVIATION...
.Cloud lines along the Florida Keys warranted an initial vicinity
shower mention for Key West, otherwise VFR is expected to prevail
through the evening. Increasing chances for showers and
thunderstorms overnight into early Sunday have resulted in elevated
vicinity shower and eventual thunder for both Marathon and Key West
from roughly midnight through 18Z Sunday. As timing becomes more
defined, some temporary IFR visibilities in showers and
thunderstorms may be introduced. Surface winds for the remainder of
the day will be mainly northeast 5 to 10 knots, eventually becoming
east early Sunday and increasing closer to 10 knots. AVIATION...

&&

.CLIMATE...
In 1929, the daily record low temperature of 72F was last
recorded in Key West. Temperature records have been kept since
1872.

&&

.PRELIMINARY POINT TEMPS/POPS...
Key West 81 89 85 90 / 50 70 30 40
Marathon 81 92 85 93 / 50 70 30 40

&&

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

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

Visit us on the web at weather.gov/key

Follow us on Facebook and Twitter at:
www.facebook.com/nwskeywest
www.twitter.com/nwskeywest

Hazardous Weather Outlook
National Weather Service Key West FL
539 AM EDT Sat Aug 19 2017

FLZ076>078-GMZ031>035-042>044-052>055-072>075-201000-
Monroe Upper Keys-Monroe Middle Keys-Monroe Lower Keys-
Florida Bay including Barnes Sound, Blackwater Sound, and
Buttonwood Sound-
Bayside and Gulf side from Craig Key to west end of Seven Mile
Bridge-
Gulf waters from East Cape Sable to Chokoloskee 20 to 60 NM out
and beyond 5 fathoms-
Gulf of Mexico including Dry Tortugas and Rebecca Shoal Channel-
Gulf of Mexico from west end of Seven Mile Bridge to Halfmoon
Shoal out to 5 Fathoms-
Hawk Channel from Ocean Reef to Craig Key out to the reef-
Hawk Channel from Craig Key to west end of Seven Mile Bridge out
to the reef-
Hawk Channel from west end of Seven Mile Bridge to Halfmoon Shoal
out to the reef-
Straits of Florida from Ocean Reef to Craig Key out 20 NM-
Straits of Florida from Craig Key to west end of Seven Mile
Bridge out 20 NM-
Straits of Florida from west end of Seven Mile Bridge to south of
Halfmoon Shoal out 20 NM-
Straits of Florida from Halfmoon Shoal to 20 NM west of Dry
Tortugas out 20 NM-
Straits of Florida from Ocean Reef to Craig Key 20 to 60 NM out-
Straits of Florida from Craig Key to west end of Seven Mile
Bridge 20 to 60 NM out-
Straits of Florida from west end of Seven Mile Bridge to south of
Halfmoon Shoal 20 to 60 NM out-
Straits of Florida from Halfmoon Shoal to 20 NM west of Dry
Tortugas 20 to 60 NM out-
539 AM EDT Sat Aug 19 2017

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE FLORIDA KEYS AND ADJACENT
COASTAL WATERS.

.DAY ONE...TODAY AND TONIGHT

Isolated to scattered thunderstorms will impact the Florida Keys,
as well as nearshore and offshore waters surrounding the island
chain today and tonight. The primary thunderstorm hazards are wind
gusts near 40 mph and cloud to surface lightning strikes.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

Scattered thunderstorms are possible along the Florida Keys, as
well as over nearshore and offshore waters adjacent to the island
chain Sunday. The primary thunderstorm hazards will be wind gusts
near 40 mph, locally heavy rainfall, and cloud to surface
lightning strikes.

Isolated thunderstorms are possible along the Florida Keys, as
well as over nearshore and offshore waters surrounding the island
chain Sunday night through Friday. The primary thunderstorm hazard
will be cloud to surface lightning strikes.

A Small Craft Advisory may be required for the coastal waters of
the Florida Straits Sunday night. A Small Craft Advisory may be
required for all Keys coastal waters Monday and Monday night.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated.

BS

Special Weather Statement
National Weather Service Key West FL
838 PM EDT SAT AUG 19 2017

FLZ078-200115-
Monroe Lower Keys FL-
838 PM EDT SAT AUG 19 2017

...SIGNIFICANT WEATHER ADVISORY FOR LOWER KEYS IN MONROE COUNTY UNTIL
915 PM EDT...

At 838 PM EDT, National Weather Service Meteorologists detected a
strong thunderstorm over Key West, moving west at 15 mph.

Wind gusts up to 50 mph will be possible with this storm.

Locations impacted include...
Key West, Fleming Key, Key Haven and Sunset Key.

This includes US 1 between mile markers 0 and 5.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
office in Key West.

&&

LAT...LON 2461 8173 2455 8173 2452 8182 2459 8182
TIME...MOT...LOC 0038Z 096DEG 14KT 2457 8178

KN