Special Marine Warning 46, NWS Key West, FL

Area Forecast Discussion
National Weather Service Key West FL
1047 AM EDT Sun Jun 13 2021

.DISCUSSION...
Broadly cyclonic low-level flow over the eastern Gulf of Mexico,
combined with a weakened ridge axis over the distant Straits of
Florida and Cuba, are maintaining a vigorous convergence zone over
the Straits of Florida. Since sunrise, storms within this
convergence zone have proliferated and inched to the north towards
the island chain. Aloft, there is diffluence near the Cay Sal
Bank, ridging over the Western Caribbean, the Yucatan, and the Bay
of Campeche, and broadly cyclonic flow over the eastern Gulf and
Florida. The Florida Keys are within a weakly inhibited,
moderately unstable environment, although deep layer moisture is
lacking somewhat (see dewpoint depressions in the lower
troposphere on the 12Z KKEY RAOB). There were very few height
changes at the SGLs this morning, slight falls aloft and slight
rises down low.

The forecast calls for 50% rain and thunder chances through the
afternoon. We considered lowering rain chances somewhat given the
meager dry slot analyzed over the extreme southeastern Gulf of
Mexico, and the lack of cumulus and radar returns near the island
chain. However, southerlies apparent on visibile satellite imagery
between Havana and Varadero, favorable Corfidi vectors along and
north of the thunderstorms to our south, and mainly southwesterly
steering, should allow the convergence zone over the Straits to
work northward over the next several hours. The one negative would
be the 6-7 degree dewpoint depressions around 900 mb, which would
tend to favor collapsing outflows and dry air entrainment at the
level of convective initiation. Given the lowest value from the
ECM guidance is 38%, we will hold at 50%.

&&

.MARINE...
There are no watches, warnings, or advisories currently in effect
for the coastal waters of the Florida Keys. Weak ridging will
remain across the Florida Keys and South Florida through
Wednesday, resulting in light to gentle breezes. However, above
normal chances for showers and thunderstorms are expected through
Wednesday as well. The ridge will lift northeast and strengthen
slightly, while lower pressure gradually develops near the Bay of
Campeche. Breezes will become east and become gentle to moderate
by Thursday.

&&

.AVIATION...
VFR conditions will prevail at both EYW and MTH island terminals
thorough this evening. Scattered showers and thunderstorms are
expected to develop this afternoon. This will result in bouts of
MVFR ceilings and potentially IFR visibilities. Confidence in timing
and impacts is too low to include anything other than VCTS in the
TAFs at this time. Southwest to west winds will be sustained at 5 to
8 knots, with gusty winds in the vicinity of any stronger
thunderstorm activity.

&&

.PRELIMINARY POINT TEMPS/POPS...
Key West  87  79  87  80 / 50 60 50 40
Marathon  91  79  90  80 / 50 60 60 40

&&

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

Public/Marine/Fire...CLR
Aviation/Nowcasts....BT
Data Acquisition.....JAM

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Hazardous Weather Outlook
National Weather Service Key West FL
534 AM EDT Sun Jun 13 2021

FLZ076>078-GMZ031>035-042>044-052>055-072>075-141000-
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-
534 AM EDT Sun Jun 13 2021

This Hazardous Weather Outlook is for the Florida Keys and
adjacent coastal waters.

.DAY ONE...TODAY AND TONIGHT

Scattered thunderstorms are expected today and tonight. The
primary thunderstorm hazards will be cloud to surface lightning
strikes, gusty winds, and brief heavy downpours.

In addition, waterspouts will be possible over the Florida Keys
coastal waters.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

Higher than normal rain chances are expected Monday through
Wednesday, allowing for scattered thunderstorms. Isolated
thunderstorms are possible Wednesday night through late Thursday,
and returning again Saturday. The primary thunderstorm hazards
will be cloud to surface lightning strikes and gusty winds.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE KEY WEST FL
120 PM EDT SUN JUN 13 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1255 PM     WATER SPOUT      5 NNW LOWER MATECUMBE K 24.93N 80.76W
06/13/2021                   GMZ031             FL   PARK/FOREST SRVC

            A FAMILY OF WATERSPOUTS WAS SPOTTED BY A PARK RANGER IN
            THE FLORIDA BAY. NO MENTION OF SPRAY RINGS IN REPORT.

&&

JAM