Special Marine Warning 310, NWS Key West, FL

103 
FZUS72 KKEY 010355
MWSKEY

Marine Weather Statement
National Weather Service Key West FL
1155 PM EDT Fri Jul 31 2020

GMZ032-033-035-043-044-053-054-073-074-010415-
/O.CON.KKEY.MA.W.0310.000000T0000Z-200801T0415Z/
1155 PM EDT Fri Jul 31 2020

...A SPECIAL MARINE WARNING REMAINS IN EFFECT UNTIL 1215 AM EDT...

For the following areas...
Hawk Channel and Straits of Florida from Craig Key to Halfmoon Shoal
out 60 nm...
Bay and Gulf Side from Craig Key to Halfmoon Shoal out to 5
fathoms...
Gulf Waters from East Cape Sable to Chokoloskee 20 to 60 nm out and
beyond 5 fathoms...

At 1154 PM EDT, squalls were located along a line extending from 
near Content Keys to 17 nm southeast of Big Pine Shoal, moving west 
at 35 knots.

HAZARD...Wind gusts 34 knots or greater.

SOURCE...National Weather Service Meteorologist.

IMPACT...Expect wind gusts in excess of 34 knots, suddenly higher 
         waves, and heavy downpours.

Locations in the warning include...
Big Pine Shoal, Annette Key, Howe Key, Bonefish Tower, Snipe Point,
Ninefoot Shoal and Money Key.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Boaters should seek safe harbor now, and remain there until
threatening weather has passed.

Prepare for wind gusts in excess of 34 knots, steep and fast-
building seas, and blinding downpours. Make sure all on board are 
wearing life jackets.

&&

LAT...LON 2439 8162 2503 8179 2511 8149 2510 8148
      2512 8107 2513 8105 2484 8093 2447 8089
      2397 8101 2371 8127
TIME...MOT...LOC 0354Z 073DEG 36KT 2486 8143 2432 8118 

HAIL...0.00IN
WIND...>34KTS

$$

SDR

Area Forecast Discussion
National Weather Service Key West FL
627 PM EDT Fri Jul 31 2020

.SHORT TERM...(Tonight through Monday)
Most weather interest in the Florida Keys over the next 24-36
hours will be on Hurricane Isaias. At 5 pm, the hurricane was
centered about 195 miles south-southeast of Nassau and was moving
to the northwest at 15 mph. It will reach the Northwest Bahamas on
Saturday and be near the east coast of the Florida Peninsula from
Saturday afternoon through Sunday.

The 5 pm NHC advisory package made another small westward shift to
the track during the storm's closest approach to the Upper Keys.
Accordingly, the cumulative probability of sustained tropical-
storm force winds at Ocean Reef has increased from 25 percent to
40 percent since the 11 am advisory. Further down the Keys at
Marathon, the probability only increased from 10 percent to 11
percent. So we have almost eaten through the margin of error for
keeping the far Upper Keys out of tropical-storm force winds. The
Middle and Lower Keys are still confidently far from the forecast
envelope of such winds.

With this update, have issued a marine-based Tropical Storm
Warning for the far northeast Straits of Florida off the Upper
Keys and beyond the Reef. Land areas and Hawk Channel remain out
of the warning.

As the hurricane passes by to our east and northeast on Saturday
and Saturday night, our winds should peak around Saturday morning
and then diminish nicely over the course of Saturday night. Wind
direction will also gradually shift from northeast to northwest.

Being on the left side of the hurricane has advantages. We are
looking for neither flooding rains nor tornadoes. In the Lower
Keys, a casual observer may even remember it as a nice day, albeit
breezy at times. Rain chances will taper off sharply as you move
down the Keys, ranging from likely PoPs with gusty squalls over
the Upper Keys to scattered showers for the Lower Keys.

By Sunday afternoon, Isaias will be closest to the Space Coast and
continuing to exit north. It looks like a tail-like feature or
trough will extend south to the Keys, maintaining a light
southwest wind and a few lines of showers aligning with the wind.
This wind flow may be conducive for reverse cloud line development
over the Keys, and the attendant risk of convective activity and
perhaps a waterspout.

That trailing trough and focus for showers will linger on Monday.
A dull surface ridge axis may try to start building back across
the Central Bahamas and South Florida late Monday or Monday night,
bringing a transition back to light east-southeast flow for the
Keys. Precipitable Water (PW) values approaching 2" will keep the
air mass juiced for pulsy convection in the light-wind regime.

&&

.LONG TERM...(Tuesday through next Friday)
Slightly above-climo rain chances and gentle breezes will prevail.

At least Tuesday through Thursday will be marked by a weakness in
the subtropical 500 mb ridge axis over the eastern Gulf, thanks to
a mid-latitude trough that will dig unseasonably far south down
the Mississippi Valley on Tuesday. That trough will slowly move
east across the Southeast U.S. through Friday, possibly becoming
less amplified around Friday. At the surface, only a weak and
ill-defined Atlantic ridge axis will extend across Central
Florida. Given the weakness of high pressure and Precipitable
Water (PW) values hovering near the 75th percentile for early
August, it should be a convectively bubbly environment and support
above normal rain chances.

&&

.MARINE...
The 5 pm NHC advisory on Hurricane Isaias included another slight
westward adjustment to the forecast track of Hurricane Isaias as
it moves northwest through the Bahamas on Saturday. This
necessitated the issuance of a Tropical Storm Warning for the far
northeast Straits off the Upper Keys and beyond the Reef.
Strongest winds should come on Saturday morning. However, it will
take until late Saturday night for seas in that region to subside
as the hurricane moves over the Gulf Stream off the east coast of
the Florida Peninsula.

Otherwise, winds through Saturday evening will gradually shift
from northeast to north to northwest and then west. Winds over
all waters will ease nicely late Saturday into Saturday night, as
the hurricane exits northward close to the FL east coast.

A weak and ill-defined Atlantic ridge axis will build
back west across Central Florida from Monday night through next
Wednesday, bringing gentle east-southeast breezes.

&&

.AVIATION...
VFR conditions will prevail at the Key West and Marathon terminals
this evening and overnight. Winds have increased slightly as
previously advertised and will maintain strength through the
overnight. There will be showers along with gusty winds associated
with squalls moving westward at times. However, exact placement
remains uncertain and any mention of VCSH will have to be added as
they get closer to the terminals. Chances are higher at the MTH
terminal.

&&

.PRELIMINARY POINT TEMPS/POPS...
Key West  82  91  82  91 / 20 40 40 40
Marathon  81  91  80  91 / 30 50 50 40

&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...Small Craft Advisory for GMZ031-032-035-042>044-053-054-073-074.

     Tropical Storm Warning for GMZ052-072.

&&

Public/Marine/Fire...Haner
Aviation/Nowcasts....LIW
Data Acquisition.....NB

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Hazardous Weather Outlook
National Weather Service Key West FL
438 AM EDT Fri Jul 31 2020

FLZ076>078-GMZ031>035-042>044-052>055-072>075-010900-
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-
438 AM EDT Fri Jul 31 2020

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

.DAY ONE...TODAY AND TONIGHT

Isolated thunderstorms will be possible today and tonight, with
locally gusty winds and lightning being the primary hazards.

A Small Craft Advisory is expected for at least a portion of the
coastal waters beginning tonight. The highest confidence is across
the eastern Hawk Channel and Florida Straits, off of the Middle
and Upper Keys.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

Hurricane Isaias is expected to remain well east of the Florida
Keys and adjacent coastal waters as it treks northward on
Saturday, but a Small Craft Advisory may still be needed for
eastern portions of the coastal waters through at least Saturday
morning.

Isolated to scattered thunderstorms will also be possible
Saturday through Thursday, with locally gusty winds and cloud to
surface lightning strikes being the primary hazards.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated.

WLC

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE KEY WEST FL
1110 PM EDT FRI JUL 31 2020

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

1030 PM     MARINE TSTM WIND 4 SE TEATABLE KEY       24.85N 80.62W
07/31/2020  M41 MPH          GMZ042             FL   MESONET

            A WIND GUST OF 35 KNOTS, OR 41 MPH, WAS RECORDED AT THE
            WEATHERFLOW MESONET STATION AT ALLIGATOR REEF LIGHT AT
            1030 PM EDT. THIS GUST WAS ASSOCIATED WITH A PASSING
            SHOWER.

&&

NB