Hurricane Isaias Intermediate Advisory Number 17A
NWS National Hurricane Center Miami FL AL092020
800 AM EDT Sat Aug 01 2020
SUMMARY OF 800 AM EDT...1200 UTC...INFORMATION
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LOCATION...24.3N 77.5W
ABOUT 20 MI...30 KM E OF ANDROS ISLAND BAHAMAS
ABOUT 50 MI...85 KM S OF NASSAU BAHAMAS
MAXIMUM SUSTAINED WINDS...85 MPH...140 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
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CHANGES WITH THIS ADVISORY:
The Hurricane Warning for the Central Bahamas 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 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
A Tropical Storm Watch is in effect for...
* Volusia/Flagler 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 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
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At 800 AM EDT (1200 UTC), the center of Hurricane Isaias was located by NOAA and Air Force Reserve Hurricane Hunter aircraft and Bahamas radar near latitude 24.3 North, longitude 77.5 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 turn toward the north-northwest by late Sunday. On the forecast track, the center of Isaias will move near or over Andros Island in the Northwestern Bahamas this morning and continue to move near or over the rest of Northwestern Bahamas later today, and move near the east coast of the Florida peninsula tonight through Sunday.
Reports from the reconnaissance aircraft indicate that maximum sustained winds remain near 85 mph (140 km/h) with higher gusts. Little change in strength is expected through Sunday, and Isaias is forecast to remain a hurricane during this time.
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).
The minimum central pressure recently measured by the aircraft was 987 mb (29.15 inches).
HAZARDS AFFECTING LAND
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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 later 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.
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 into Virginia.
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 today. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office.
