[Tropical] Public Tropical Cyclone Advisory

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WTNT34 KNHC 011447
TCPAT4

BULLETIN
Hurricane Isaias Advisory Number  18
NWS National Hurricane Center Miami FL       AL092020
1100 AM EDT Sat Aug 01 2020

...ISAIAS MAKING LANDFALL ON NORTHERN ANDROS ISLAND...
...EXPECTED TO APPROACH THE SOUTHEAST COAST OF FLORIDA LATER TODAY
AND SUNDAY...


SUMMARY OF 1100 AM EDT...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...24.7N 77.9W
ABOUT 40 MI...60 KM WSW OF NASSAU
ABOUT 135 MI...220 KM SSE OF FREEPORT GRAND BAHAMA ISLAND
MAXIMUM SUSTAINED WINDS...80 MPH...130 KM/H
PRESENT MOVEMENT...NW OR 315 DEGREES AT 12 MPH...19 KM/H
MINIMUM CENTRAL PRESSURE...987 MB...29.15 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

The Tropical Storm Watch from the Volusia/Flagler County Line to
Ponte Vedra Beach Florida has been changed to a Tropical Storm
Warning.

A Tropical Storm Watch has been issued from north of Ponte Vedra
Beach Florida to Altamaha Sound Georgia.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Hurricane Warning is in effect for...
* Boca Raton to the Volusia/Flagler County Line Florida
* Northwestern Bahamas

A Hurricane Watch is in effect for...
* Hallandale Beach to south of Boca Raton Florida

A Storm Surge Watch is in effect for...
* Jupiter Inlet to Ponte Vedra Beach Florida

A Tropical Storm Warning is in effect for...
* North of Ocean Reef to south of Boca Raton Florida
* Lake Okeechobee
* Volusia/Flagler County Line to Ponte Vedra Beach Florida

A Tropical Storm Watch is in effect for...
* North of Ponte Vedra Beach Florida to Altamaha Sound Georgia

Interests elsewhere along the southeast coast of the United States
should monitor the progress of Isaias.  Additional watches or
warnings may be required later today.

A Hurricane Warning means that hurricane conditions are expected
somewhere within the warning area. A warning is typically issued
36 hours before the anticipated first occurrence of
tropical-storm-force winds, conditions that make outside
preparations difficult or dangerous.  Preparations to protect life
and property should be rushed to completion.

A Hurricane Watch means that hurricane conditions are possible
within the watch area.  A watch is typically issued 48 hours
before the anticipated first occurrence of tropical-storm-force
winds, conditions that make outside preparations difficult or
dangerous.

A Storm Surge Watch means there is a possibility of life-
threatening inundation, from rising water moving inland from the
coastline, in the indicated locations during the next 48 hours.
For a depiction of areas at risk, please see the National Weather
Service Storm Surge Watch/Warning Graphic, available at
hurricanes.gov.

A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area within 36 hours.

A Tropical Storm Watch means that tropical storm conditions are
possible within the watch area, generally within 48 hours.

For storm information specific to your area in the United
States, including possible inland watches and warnings, please
monitor products issued by your local National Weather Service
forecast office. For storm information specific to your area
outside of the United States, please monitor products issued by
your national meteorological service.


DISCUSSION AND OUTLOOK
----------------------
At 1100 AM EDT (1500 UTC), the center of Hurricane Isaias was
located by an Air Force Reserve Hurricane Hunter aircraft and
Bahamas radar near latitude 24.7 North, longitude 77.9 West. Isaias
is moving toward the northwest near 12 mph (19 km/h). A general
northwestward motion with some decrease in forward speed is expected
for the next day or so, followed by a north-northwestward motion by
late Sunday.  On the forecast track, the center of Isaias will move
over northern Andros Island during the next few hours and move
near or over Grand Bahama Island in the Northwestern Bahamas later
today. Isaias is forecast to move near the east coast of the
Florida peninsula tonight through Sunday.

Reports from the reconnaissance aircraft indicate that maximum
sustained winds have decreased slightly to near 80 mph (130 km/h)
with higher gusts.  Little change in strength is expected through
Sunday, and Isaias is forecast to remain a hurricane during this
time. Slow weakening is expected to begin by late Monday.

Hurricane-force winds extend outward up to 25 miles (35 km) from the
center and tropical-storm-force winds extend outward up to 115 miles
(185 km). Reports from a U.S. Navy site on Andros Island indicate
that sustained winds of 45 mph (76 km/h) and a gust to 69 mph (111
km/h) occurred about 3 hours ago. More recently, a sustained wind of
35 mph (56 km/h) and a gust to 48 mph (77 km/h) were measured at
Nassau, Bahamas.

The estimated minimum central pressure is 987 mb (29.15 inches).


HAZARDS AFFECTING LAND
----------------------
Key messages for Isaias can be found in the Tropical Cyclone
Discussion under AWIPS header MIATCDAT4, WMO header WTNT44 KNHC, and
on the web at www.hurricanes.gov/text/MIATCDAT4.shtml.

STORM SURGE:  The combination of a dangerous storm surge and the
tide will cause normally dry areas near the coast to be flooded by
rising waters moving inland from the shoreline.  The water could
reach the following heights above ground somewhere in the indicated
areas if the peak surge occurs at the time of high tide...

Jupiter Inlet to Ponte Vedra Beach FL...2-4 ft
North Miami Beach to Jupiter Inlet FL...1-3 ft

The deepest water will occur along the immediate coast near and to
the right of the center, where the surge will be accompanied by
large waves.  Surge-related flooding depends on the relative timing
of the surge and the tidal cycle, and can vary greatly over short
distances.  For information specific to your area, please see
products issued by your local National Weather Service forecast
office.

A dangerous storm surge will raise water levels by as much as
3 to 5 feet above normal tide levels in areas of onshore winds in
the Northwestern Bahamas.

WIND:  Hurricane conditions will continue to spread over the
Northwestern Bahamas through today.

Hurricane conditions are expected to reach the coast within the
hurricane warning area in Florida tonight and will spread northward
through Sunday. Winds are expected to first reach tropical storm
strength later today, making outside preparations difficult or
dangerous. Preparations to protect life and property should be
rushed to completion.  Tropical storm conditions are expected within
the tropical storm warning area, and are possible within the watch
area, over southern Florida by this afternoon or evening.

Tropical storm conditions are expected in the warning area in
northeast Florida by late Sunday, and are possible in the watch
area in northeast Florida and southeast Georgia by Monday morning.

RAINFALL: Isaias is expected to produce the following rain
accumulations:

Bahamas: 4 to 8 inches.

Cuba: 1 to 2 inches, with isolated maximum totals of 4 inches.

These rainfall amounts could lead to life-threatening flash and
urban flooding, especially in low-lying and poorly drained areas.

>From Friday night through Tuesday:

South Florida into east-central Florida: 2 to 4 inches, with
isolated maximum totals of 6 inches.

Northeast Florida into coastal Georgia: 1 to 2 inches.

Carolinas into the mid Atlantic, including the southern and central
Appalachians: 2 to 4 inches, with isolated maximum totals of 6
inches.

Heavy rainfall from Isaias could result in potentially life-
threatening flash and urban flooding, especially in low-lying
and poorly drained areas. Minor river flooding is possible across
portions of the Carolinas and Virginia.

SURF:  Swells generated by Isaias are affecting portions of
Hispaniola, eastern Cuba, the Turks and Caicos, and the Bahamas.
These swells will spread along the east coast of Florida and the
southeastern United States coast today.  These swells are likely to
cause life-threatening surf and rip current conditions. Please
consult products from your local weather office.


NEXT ADVISORY
-------------
Next intermediate advisory at 200 PM EDT.
Next complete advisory at 500 PM EDT.

$$
Forecaster Stewart
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