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Tropical Storm Isaias Advisory Number 19
NWS National Hurricane Center Miami FL AL092020
500 PM EDT Sat Aug 01 2020
...ISAIAS WEAKENS TO A TROPICAL STORM...
...EXPECTED TO RE-STRENGTHEN TO A HURRICANE OVERNIGHT WHILE IT
APPROACHES THE SOUTHEAST COAST OF FLORIDA...
SUMMARY OF 500 PM EDT...2100 UTC...INFORMATION
ABOUT 115 MI...185 KM SE OF FORT LAUDERDALE FLORIDA
ABOUT 95 MI...155 KM S OF FREEPORT GRAND BAHAMA ISLAND
MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H
PRESENT MOVEMENT...NW OR 310 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...993 MB...29.33 INCHES
WATCHES AND WARNINGS
CHANGES WITH THIS ADVISORY:
The Tropical Storm Watch has been extended northward from Altamaha
Sound Georgia to South Santee River South Carolina.
The Hurricane Watch from Hallandale Beach to south of Boca Raton
Florida has been discontinued.
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 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 South Santee River South
Interests elsewhere along the southeast and mid-Atlantic coasts of
the United States should monitor the progress of Isaias. Additional
watches or warnings may be required tonight or Sunday.
A Hurricane Warning means that hurricane conditions are expected
somewhere within the warning area. Preparations to protect life
and property should be rushed to completion.
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
A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area.
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 500 PM EDT (2100 UTC), the center of Tropical Storm Isaias was
located by an Air Force Reserve reconnaissance aircraft near
latitude 25.1 North, longitude 78.7 West. Isaias is moving toward
the northwest near 10 mph (17 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
and a turn toward the north and north- northeast on Monday and
Tuesday with an increase in forward speed. On the forecast track,
the center of Isaias will approach the southeast coast of Florida
tonight and move near or along the east coast of Florida Sunday and
Sunday night. On Monday and Tuesday, the center of Isaias will move
quickly from offshore of the coast of Georgia into the southern
Maximum sustained winds have decreased to near 70 mph (110 km/h)
with higher gusts. Some restrengthening is forecast, and Isaias
is expected to regain hurricane strength tonight. Slow weakening is
expected to begin Sunday night and continue through Monday.
Tropical-storm-force winds extend outward up to 105 miles (165 km)
from the center. During hew past couple of hours, a Weatherflow
observing site at the Dania Pier in Broward County, Florida,
reported a wind gust to 59 mph (94 km/h) in an outer rainband. More
recently, a wind gust to 41 mph (67 km/h) was reported by a
Weatherflow site in Juno Beach, Florida.
The estimated minimum central pressure based on reconnaissance
aircraft data is 993 mb (29.33 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
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 and tropical storm conditions will continue to
spread over portions of the Northwestern Bahamas tonight.
Hurricane conditions are expected to reach the coast within the
hurricane warning area in Florida on Sunday and will spread
northward through Sunday night. Winds are expected to first reach
tropical storm strength later tonight, 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 in South Florida
Tropical storm conditions are expected in the warning area in
northeast Florida by Sunday night, and are possible in the watch
area from northeast Florida to South Carolina on Monday.
RAINFALL: Isaias is expected to produce the following rain
Bahamas: 4 to 8 inches, with isolated maximum totals of 12 inches.
Cuba: 1 to 2 inches, with isolated maximum totals of 4 inches.
Eastern Florida: 2 to 4 inches, with isolated maximum totals of 6
Northeast Florida and coastal Georgia: 1 to 3 inches.
Carolinas and the mid Atlantic, including the southern and central
Appalachians: 2 to 5 inches, with isolated maximum totals of 7
Southeast New York and much of New England: 2 to 4 inches, with
isolated maximum totals of 6 inches.
Heavy rainfall from Isaias could result in potentially life-
threatening flash flooding in the Bahamas and flash and urban
flooding along the East Coast of the United States. Minor river
flooding and isolated moderate 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 through Sunday. These swells are
likely to cause life-threatening surf and rip current conditions.
Please consult products from your local weather office.
Next intermediate advisory at 800 PM EDT.
Next complete advisory at 1100 PM EDT.