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Hurricane Isaias Intermediate Advisory Number 15A
NWS National Hurricane Center Miami FL AL092020
800 PM EDT Fri Jul 31 2020
...TROPICAL STORM CONDITIONS AND HEAVY RAIN CONTINUE TO SPREAD
ACROSS THE CENTRAL BAHAMAS...
SUMMARY OF 800 PM EDT...0000 UTC...INFORMATION
ABOUT 175 MI...280 KM SSE OF NASSAU
ABOUT 310 MI...500 KM SE OF FREEPORT GRAND BAHAMA ISLAND
MAXIMUM SUSTAINED WINDS...80 MPH...130 KM/H
PRESENT MOVEMENT...NW OR 310 DEGREES AT 15 MPH...24 KM/H
MINIMUM CENTRAL PRESSURE...987 MB...29.15 INCHES
WATCHES AND WARNINGS
CHANGES WITH THIS ADVISORY:
The government of the Bahamas has discontinued the Hurricane
Warning for the Southeastern Bahamas, and discontinued the Tropical
Storm Warning for the Turks and Caicos Islands.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Hurricane Warning is in effect for...
* Boca Raton to the Volusia/Brevard County Line Florida
* Northwestern Bahamas
* Central Bahamas
A Hurricane Watch is in effect for...
* Hallendale Beach to south of Boca Raton Florida
* Volusia-Brevard County Line to the Flagler/Volusia County Line
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
A Tropical Storm Watch is in effect for...
* Flagler/Volusia County Line to Ponte Vedra Beach Florida
Interests elsewhere along the southeast coast of the United States
should monitor the progress of Isaias. Additional watches or
warnings may be required later tonight and Saturday.
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
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 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 800 PM EDT (0000 UTC), the center of Hurricane Isaias was located
by Air Force and NOAA Hurricane Hunter aircraft near latitude 22.9
North, longitude 75.9 West. Isaias is moving toward the northwest
near 15 mph (24 km/h), and a general northwestward motion with some
decrease in forward speed is expected for the next day or so,
followed by a turn toward the north-northwest by late Sunday. On
the forecast track, the center of Isaias will move near or over the
Central Bahamas tonight, near or over the Northwestern Bahamas
Saturday and near the east coast of the Florida peninsula Saturday
afternoon through Sunday.
Maximum sustained winds are near 80 mph (130 km/h) with higher
gusts. Additional strengthening is expected later tonight and early
Saturday, and Isaias is forecast to remain a hurricane for the next
couple of days.
Hurricane-force winds extend outward up to 35 miles (55 km) from
the center and tropical-storm-force winds extend outward up to 175
miles (280 km). Staniel Cay in the Exumas recently reported
sustained winds of 40 mph (65 km/h) with a gust to 52 mph (83 km/h).
The minimum central pressure estimated from Air Force Hurricane
Hunter aircraft observations 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
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 Bahamas.
WIND: Hurricane conditions will continue to spread northwestward
into the central and northwestern Bahamas tonight and Saturday.
Hurricane conditions are expected to reach the coast within the
hurricane warning area in Florida late Saturday and Saturday night.
Winds are expected to first reach tropical storm strength on
Saturday, making outside preparations difficult or dangerous.
Preparations to protect life and property should be rushed to
RAINFALL: Isaias is expected to produce the following rain
Bahamas, Turks and Caicos: 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
Heavy rainfall from Isaias could result in isolated flash and urban
flooding, especially in low-lying and poorly drained areas. Isolated
minor river flooding is possible across the eastern Carolinas and
SURF: Swells generated by Isaias are affecting portions of
Hispaniola, eastern Cuba, the Turks and Caicos, and the southeastern
and central Bahamas. These swells will spread along the east coast
of Florida and the southeastern United States coast on Saturday.
These swells are likely to cause life-threatening surf and rip
current conditions. Please consult products from your local
Next complete advisory at 1100 PM EDT.