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Hurricane Irma Advisory Number 49
NWS National Hurricane Center Miami FL AL112017
500 AM EDT Mon Sep 11 2017
...IRMA CONTINUES TO WEAKEN AS THE CENTER MOVES ALONG THE
NORTHWESTERN COAST OF THE FLORIDA PENINSULA...
SUMMARY OF 500 AM EDT...0900 UTC...INFORMATION
ABOUT 35 MI...55 KM ESE OF CEDAR KEY FLORIDA
ABOUT 60 MI...100 KM N OF TAMPA FLORIDA
MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/H
PRESENT MOVEMENT...NNW OR 340 DEGREES AT 18 MPH...30 KM/H
MINIMUM CENTRAL PRESSURE...965 MB...28.50 INCHES
WATCHES AND WARNINGS
CHANGES WITH THIS ADVISORY:
The Hurricane Warning is changed to a Tropical Storm Warning along
the Florida west coast south of Anclote River to Bonita Beach, along
the Florida east coast south of Sebastian Inlet to Jupiter Inlet,
and for Lake Okeechobee.
The Tropical Storm Warnings are discontinued for the Florida Keys,
Florida Bay, the Florida east coast south of Jupiter Inlet,
the Florida west coast south of Bonita Beach, and for the
The Storm Surge Warning is discontinued for the Florida Keys and
the Florida coast from North Miami Beach southward around the
Florida peninsula to Cape Sable.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Storm Surge Warning is in effect for...
* South Santee River southward to Jupiter Inlet
* Cape Sable northward to the Ochlockonee River
* Tampa Bay
A Hurricane Warning is in effect for...
* Sebastian Inlet to Fernandina Beach
* Anclote River to Indian Pass
A Hurricane Watch is in effect for...
* North of Fernandina Beach to Edisto Beach
A Tropical Storm Warning is in effect for...
* West of Indian Pass to the Okaloosa/Walton County Line
* North of Fernandina Beach to South Santee River
* South of Anclote River to Bonita Beach
* South of Sebastian Inlet to Jupiter Inlet
* Lake Okeechobee
A Storm Surge Warning means there is a danger of life-threatening
inundation, from rising water moving inland from the coastline,
during the next 36 hours in the indicated locations. For a
depiction of areas at risk, please see the National Weather
Service Storm Surge Watch/Warning Graphic, available at
hurricanes.gov. This is a life-threatening situation. Persons
located within these areas should take all necessary actions to
protect life and property from rising water and the potential for
other dangerous conditions. Promptly follow evacuation and other
instructions from local officials.
Interests elsewhere in the southeastern United States should monitor
the progress of Irma.
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
the United States, please monitor products issued by your national
DISCUSSION AND 48-HOUR OUTLOOK
At 500 AM EDT (0900 UTC), the center of Hurricane Irma was located
near latitude 28.9 North, longitude 82.6 West. Irma is moving toward
the north-northwest near 18 mph (30 km/h) and this motion is
expected to continue through Tuesday. On the forecast track, the
center of Irma will move near the northwestern coast of the Florida
Peninsula this morning, cross the eastern Florida Panhandle into
southern Georgia this afternoon, and move through southwestern
Georgia and eastern Alabama tonight and Tuesday.
Maximum sustained winds have decreased to near 75 mph (120 km/h)
with higher gusts. Additional weakening is forecast, and Irma is
expected to weaken to a tropical storm this morning and to a
tropical depression by Tuesday afternoon.
Irma has a very large wind field. Hurricane-force winds extend
outward up to 60 miles (95 km) mainly to the west of the center, and
tropical-storm-force winds extend outward up to 415 miles (665 km).
The Mayport Naval Station near Jacksonville, Florida, recently
reported sustained winds of 68 mph (109 km/h) and a wind gust of 87
mph (141 km/h).
The estimated minimum central pressure is 965 mb (28.50 inches).
HAZARDS AFFECTING LAND
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 is
expected to reach the following HEIGHTS ABOVE GROUND if the peak
surge occurs at the time of high tide...
Cape Sable to Captiva...2 to 4 ft
Captiva to Anna Maria Island...3 to 5 ft
North Miami Beach to Cape Sable, including the Florida Keys...1 to 2
Anna Maria Island to Clearwater, including Tampa Bay...2 to 4 ft
South Santee River to Fernandina Beach...4 to 6 ft
Clearwater Beach to Ochlockonee River...4 t 6 ft
Fernandina Beach to Jupiter Inlet...3 to 5 ft
The deepest water will occur along the immediate coast in areas of
onshore winds, where the surge will be accompanied by large and
destructive 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
WIND: Hurricane conditions should continue over portions of the
northern Florida peninsula for the next several hours. Tropical
storm conditions will continue across other portions of the central
and northern Florida peninsula, and spread into the eastern Florida
Panhandle and southern Georgia this morning. Tropical storm and
hurricane conditions are expected to spread northward across the
remainder of the warning areas through today.
Rainfall: Irma is expected to produce the following rain
accumulations through Wednesday:
The Florida Keys and southern Florida peninsula: additional 1 inch.
Central Florida peninsula: additional 1 to 3 inches.
Northern Florida peninsula and southern Georgia: additional 3 to 6
inches with storm total amounts of 8 to 15 inches.
Central Georgia, eastern Alabama and southern South Carolina: 3 to
inches, isolated 10 inches.
Central Florida Panhandle, western Alabama, northern Mississippi,
southern Tennessee, northern Georgia, northern South Carolina and
western North Carolina: 2 to 4 inches.
TORNADOES: A few tornadoes are possible across northeast Florida
and southeast portions of Georgia and South Carolina through
SURF: Swells generated by Irma are affecting the southeast coast of
the United States. 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 AM EDT.
Next complete advisory at 1100 AM EDT.