Florida in the Crosshairs – Irma on the Way

NOAA

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WTNT41 KNHC 091458
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Hurricane Irma Discussion Number 42
NWS National Hurricane Center Miami FL AL112017
1100 AM EDT Sat Sep 09 2017

The interaction of Irma’s circulation with Cuba has resulted in
some weakening of the hurricane. Data from an Air Force plane
indicate that the maximum winds are now 110 kt. However, once the
circulation moves away from Cuba, restrengthening is forecast and
Irma is expected to remain a very dangerous hurricane for the next 2
days while moving very near the Florida peninsula.

The eye has been moving toward the west or 280 degrees at about 8
kt. The hurricane is about the reach the southwestern portion of
the subtropical high, and the expected turn to the northwest and
north-northwest should begin soon. The track guidance is tightly
packed and takes the hurricane over the Florida Keys and near or
over the Florida Peninsula. The NHC forecast is in the middle of
the guidance envelope and given the good agreement among models, the
confidence in the track forecast is high.

Irma is now under the scope of Key West radar, so hourly updates
will begin at 1600 UTC.

KEY MESSAGES:

1. Irma will continue to bring life-threatening wind, storm surge,
and rainfall hazards to portions of the Bahamas and the north coast
of Cuba, especially over the adjacent Cuban Keys, through tonight.

2. Irma is expected to make landfall in Florida as an extremely
dangerous major hurricane, bringing life-threatening wind
impacts to much of the state regardless of the exact track of the
center. Wind hazards from Irma are also expected to spread northward
along the coast of Georgia and South Carolina where a Hurricane
Watch has been issued.

3. There is an imminent danger of life-threatening storm surge
flooding in portions of central and southern Florida, including the
Florida Keys, where a Storm Surge Warning is in effect. The threat
of catastrophic storm surge flooding is highest along the southwest
coast of Florida, where 10 to 15 feet of inundation above ground
level is expected. This is a life-threatening situation and everyone
in these areas should immediately follow any evacuation instructions
from local officials.

4. Irma is expected to produce very heavy rain and inland flooding.
Total rain accumulations of 10 to 20 inches, with isolated amounts
of between 20 and 25 inches, are expected over the Florida Keys, the
Florida peninsula, and southeast Georgia from Saturday through
Monday. Significant river flooding is possible in these areas. Early
next week Irma will also bring periods of heavy rain to much of the
southeast United States where an average of 2 to 6 inches is
forecast, with isolated higher amounts, from North and South
Carolina to Tennessee and eastern Alabama. This includes some
mountainous areas which are more prone to flash flooding. Residents
throughout the southeast states should remain aware of the flood
threat and stay tuned to forecasts and warnings.

 

FORECAST POSITIONS AND MAX WINDS

INIT 09/1500Z 22.8N 79.8W 110 KT 125 MPH
12H 10/0000Z 23.4N 80.7W 115 KT 130 MPH
24H 10/1200Z 24.5N 81.6W 120 KT 140 MPH
36H 11/0000Z 26.4N 82.1W 120 KT 140 MPH
48H 11/1200Z 29.0N 82.8W 100 KT 115 MPH
72H 12/1200Z 34.5N 86.0W 25 KT 30 MPH…POST-TROP/INLAND
96H 13/1200Z 36.0N 89.0W 25 KT 30 MPH…POST-TROP/INLAND
120H 14/1200Z 37.0N 88.5W 20 KT 25 MPH…POST-TROP/INLAND

$$
Forecaster Avila

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BULLETIN
Hurricane Irma Advisory Number 42
NWS National Hurricane Center Miami FL AL112017
1100 AM EDT Sat Sep 09 2017

…IRMA CONTINUES TO POUND THE NORTH COAST OF CUBA…
…FORECAST TO RESTRENGTHEN WHILE HEADING FOR SOUTH FLORIDA AND THE
KEYS…

 

SUMMARY OF 1100 AM EDT…1500 UTC…INFORMATION
———————————————–
LOCATION…22.8N 79.8W
ABOUT 90 MI…145 KM ESE OF VARADERO CUBA
ABOUT 175 MI…285 KM SE OF KEY WEST FLORIDA
MAXIMUM SUSTAINED WINDS…125 MPH…205 KM/H
PRESENT MOVEMENT…W OR 280 DEGREES AT 9 MPH…15 KM/H
MINIMUM CENTRAL PRESSURE…941 MB…27.79 INCHES

 

WATCHES AND WARNINGS
——————–
CHANGES WITH THIS ADVISORY:

The Storm Surge Warning has been extended from Chassahowitzka to the
Suwanee River.

The Storm Surge Watch has been extended from north of the Suwanee
River to Ochlockonee River and from north of the Volusia/Brevard
County line north to Isle of Palms, South Carolina.

The Hurricane Warning for the east coast of the United States
has been extended northward to Fernandina Beach, and the Hurricane
Watch has been extended from north of Fernandina Beach to Edisto
Beach.

The Hurricane Warning for the Gulf of Mexico coast has been
extended to the Aucilla River. The Hurricane Watch is now in
effect from west of the Aucilla River to Indian Pass.

A Tropical Storm Watch has been issued from north of Edisto Beach
to the South Santee River.

A Tropical Storm Watch has been issued from west of Indian Pass to
the Okaloosa/Walton County Line.

The government of Cuba has extended the Hurricane Warning to the
Havana province.

The government of the Bahamas has adjusted the Hurricane Warning
to only include Andros Island, Bimini and Grand Bahama.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Storm Surge Warning is in effect for…
* Volusia/Brevard County line southward around the Florida
peninsula to the Suwanee River
* Florida Keys
* Tampa Bay

A Storm Surge Watch is in effect for…
* North of the Volusia/Brevard County line to the Isle of Palms,
South Carolina
* North of the Suwanee River to Ochlockonee River

A Hurricane Warning is in effect for…
* Fernandina Beach southward around the Florida peninsula to
the Aucilla River
* Florida Keys
* Lake Okeechobee
* Florida Bay
* Cuban provinces of Camaguey, Ciego de Avila, Sancti Spiritus,
Villa Clara, Matanzas, and Havana
* Andros Island, Bimini and Grand Bahama

A Hurricane Watch is in effect for…
* North of Fernandina Beach to Edisto Beach
* West of the Aucilla River to Indian Pass
* Cuban provinces of Holguin and Las Tunas

A Tropical Storm Warning is in effect for…
* Cuban provinces of Holguin, Las Tunas

A Tropical Storm Watch is in effect for…
* North of Edisto Beach to South Santee River
* West of Indian Pass to the Okaloosa/Walton County Line

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.

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 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 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 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.

Interests elsewhere in Cuba and 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
meteorological service.

 

DISCUSSION AND 48-HOUR OUTLOOK
——————————
At 1100 AM EDT (1500 UTC), the eye of Hurricane Irma was
located by a reconnaissance plane and radar near latitude 22.8
North, longitude 79.8 West. Irma is moving toward the west along
the north coast of Cuba at near 9 mph (15 km/h). A northwest motion
is expected to begin later today with a turn toward the north-
northwest on Sunday. On the forecast track, the core of Irma will
continue to move near or over the north coast of Cuba later today,
and will reach the Florida Keys Sunday morning. The hurricane is
expected to move along or near the southwest coast of Florida Sunday
afternoon.

Maximum sustained winds are near 125 mph (205 km/h) with higher
gusts. Irma is a category 3 hurricane on the Saffir-Simpson
Hurricane Wind Scale. Irma is forecast to restrengthen once it
moves away from Cuba, and Irma is expected to remain a powerful
hurricane as it approaches Florida.

Hurricane-force winds extend outward up to 70 miles (110 km) from
the center and tropical-storm-force winds extend outward up to 195
miles (315 km). Caibarien, Cuba recently reported a wind gust to
124 mph (200 km/h).

The minimum central pressure reported by an Air Force plane was 941
mb (27.79 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…10 to 15 ft
Captiva to Ana Maria Island…6 to 10 ft
Card Sound Bridge through Cape Sable, including the Florida
Keys…5 to 10 ft
Ana Maria Island to Clearwater Beach, including Tampa Bay…5 to 8
ft
North Miami Beach to Card Sound Bridge, including Biscayne Bay…4
to 6 ft
Isle of Palms, South Carolina to Fernandina Beach…4 to 6 ft
Clearwater Beach to Ochlockonee River…4 to 6 ft
Fernandina Beach to North Miami Beach…2 to 4 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
office.

The combination of a life-threatening storm surge and large breaking
waves will raise water levels ABOVE NORMAL TIDE LEVELS by the
following amounts within the hurricane warning area near and to the
north of the center of Irma. Near the coast, the surge will be
accompanied by large and destructive waves.

Ragged Island in the Bahamas…15 to 20 ft
Central and Northwestern Bahamas…3 to 6 ft
Northern coast of Cuba in the warning area…5 to 10 ft

WIND: Hurricane conditions are expected to continue within the
hurricane warning area along the north coast of Cuba through today.
Hurricane conditions are expected in portions of the northwestern
Bahamas today, and in portions of the Florida peninsula and the
Florida Keys tonight and Sunday.

Hurricane and tropical storm conditions are possible within the
watch area on Sunday.

RAINFALL: Irma is expected to produce the following rain
accumulations through Wednesday:
Northern Cuba…10 to 15 inches, isolated 20 inches.
Southern Cuba…5 to 10 inches, isolated 15 inches.
Western Bahamas…3 to 6 inches, isolated 10 inches.
The Florida Keys…10 to 20 inches, isolated 25 inches.
The Florida peninsula and southeast Georgia…8 to 15 inches,
isolated 20 inches.
The eastern Florida Panhandle…3 to 6 inches, isolated 8 inches.
Rest of eastern Georgia, western South Carolina, and western North
Carolina…4 to 8 inches.
Western Georgia, eastern and northern Alabama, and southern
Tennessee…2 to 5 inches.
In all areas this rainfall may cause life-threatening flash floods
and, in some areas, mudslides.

TORNADOES: A few tornadoes are possible today and tonight over
southern Florida.

SURF: Swells generated by Irma are affecting the southeastern
Bahamas, the Turks and Caicos Islands and the southeast coast of the
United States 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 Avila

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