Hurricane Helene Advisory Number 9

NWS National Hurricane Center Miami FL AL092024

1000 AM CDT Wed Sep 25 2024

...HELENE BECOMES A HURRICANE...

...EXPECTED TO BRING LIFE-THREATENING STORM SURGE, DAMAGING WINDS,

AND FLOODING RAINS TO A LARGE PORTION OF FLORIDA AND THE

SOUTHEASTERN UNITED STATES...

SUMMARY OF 1000 AM CDT...1500 UTC...INFORMATION

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LOCATION...21.6N 86.3W

ABOUT 85 MI...135 KM NNE OF COZUMEL MEXICO

ABOUT 500 MI...810 KM SSW OF TAMPA FLORIDA

MAXIMUM SUSTAINED WINDS...80 MPH...130 KM/H

PRESENT MOVEMENT...NNW OR 330 DEGREES AT 10 MPH...17 KM/H

MINIMUM CENTRAL PRESSURE...979 MB...28.91 INCHES

WATCHES AND WARNINGS

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CHANGES WITH THIS ADVISORY:

The Tropical Storm Warning has been extended northward along the

coasts of Georgia and South Carolina to South Santee River, and

westward along the Florida Gulf coast to the Okaloosa/Walton County

Line.

A Storm Surge Watch has been issued from Mexico Beach to Indian

Pass, Florida.

A Tropical Storm Watch has been issued along the coast of South

Carolina north of South Santee River to Little River Inlet.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Storm Surge Warning is in effect for...

* Indian Pass southward to Flamingo

* Tampa Bay

* Charlotte Harbor

A Hurricane Warning is in effect for...

* Anclote River to Mexico Beach

* Cabo Catoche to Tulum, Mexico including Cozumel

A Storm Surge Watch is in effect for...

* West of Indian Pass to Mexico Beach

A Hurricane Watch is in effect for...

* Cuban province of Pinar del Rio

* Englewood to Anclote River, including Tampa Bay

A Tropical Storm Warning is in effect for...

* Florida Keys, including the Dry Tortugas

* Flamingo to Anclote River, including Tampa Bay

* West of Mexico Beach to the Okaloosa/Walton County Line

* Flamingo northward to South Santee River

* Lake Okeechobee

* Rio Lagartos to Cabo Catoche, Mexico

* Cuban provinces of Artemisa, Pinar del Rio, and the Isle of Youth

A Tropical Storm Watch is in effect for...

* North of South Santee River to Little River Inlet

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 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 Tropical Storm Warning means that tropical storm conditions are

expected somewhere within the warning area within the next 36 hours.

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 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 Watch means that tropical storm conditions are

possible within the watch area.

Additional watches or warnings may be required later today.

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 1000 AM CDT (1500 UTC), the center of Hurricane Helene was

located near latitude 21.6 North, longitude 86.3 West. Helene is

moving toward the north-northwest near 10 mph (17 km/h). A turn

toward the north and north-northeast with an increase in forward

speed is expected later today through Thursday, bringing the center

of Helene across the eastern Gulf of Mexico and to the Florida Big

Bend coast by Thursday evening. After landfall, Helene is expected

to slow down and turn toward the northwest over the southeastern

United States Friday and Saturday.

Data from NOAA and Air Force Reserve Hurricane Hunter aircraft

indicate that maximum sustained winds have increased to near 80 mph

(130 km/h) with higher gusts. Additional strengthening is

forecast, and Helene is expected to be a major hurricane when it

reaches the Florida Big Bend coast Thursday evening. Weakening is

expected after landfall, but Helene's fast forward speed will allow

strong, damaging winds, especially in gusts, to penetrate well

inland across the southeastern United States, including over the

higher terrain of the southern Appalachians.

Hurricane-force winds extend outward up to 25 miles (35 km) from the

center and tropical-storm-force winds extend outward up to 275 miles

(445 km).

The minimum central pressure based on dropsonde is 979 mb (28.91

inches).

HAZARDS AFFECTING LAND

----------------------

Key Messages for Helene can be found in the Tropical Cyclone

Discussion under AWIPS header MIATCDAT4 and WMO header WTNT44 KNHC

and on the web at 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...

Carrabelle, FL to Chassahowitzka, FL...10-15 ft

Chassahowitzka, FL to Anclote River, FL...6-10 ft

Indian Pass, FL to Carrabelle, FL...6-10 ft

Anclote River, FL to Middle of Longboat Key, FL...5-8 ft

Tampa Bay...5-8 ft

Middle of Longboat Key, FL to Englewood, FL...4-7 ft

Englewood, FL to Flamingo, FL...3-5 ft

Charlotte Harbor...3-5 ft

For a complete depiction of areas at risk of storm surge inundation,

please see the National Weather Service Peak Storm Surge Graphic,

available at hurricanes.gov/graphics_at4.shtml?peakSurge.

Storm surge could raise water levels by as much as 2 to 4 feet above

normal tide levels in areas of onshore winds along the southern

coast of Pinar del Rio, Cuba, including the Isle of Youth.

Storm surge could raise water levels by as much as 2 to 4 feet above

ground level in areas of onshore winds within the warning area along

the east coast of the Yucatan Peninsula.

WIND: Hurricane conditions are expected within the U.S. hurricane

warning area late Thursday, with tropical storm conditions

beginning Thursday morning. Tropical storm conditions are

expected in southern Florida later today and will spread northward

across the rest of Florida, Georgia, and South Carolina through

Thursday. Tropical storm conditions are possible within the

tropical storm watch area in South Carolina beginning on Thursday.

Hurricane conditions, especially in gusts, are expected in the

hurricane warning area in Mexico during the next several hours.

Tropical storm conditions are occurring in the warning area in Cuba,

and hurricane conditions are possible for the western portion of

Cuba today.

RAINFALL: Helene is expected to produce total rain accumulations of

4 to 8 inches over western Cuba, the Cayman Islands, and the

northeast Yucatan Peninsula, with isolated totals around 12 inches.

This rainfall brings a risk of considerable flooding.

Over the Southeastern U.S. into the Southern Appalachians, Helene

is expected to produce total rain accumulations of 5 to 10 inches

with isolated totals around 15 inches. This rainfall will likely

result in areas of considerable flash and urban flooding, with areas

of significant river flooding. Landslides are possible in areas of

steep terrain in the southern Appalachians.

For a complete depiction of forecast rainfall associated with

Helene, please see the National Weather Service Storm Total Rainfall

Graphic, available at hurricanes.gov/graphics_at4.shtml?rainqpf and

the Flash Flood Risk graphic at

hurricanes.gov/graphics_at4.shtml?ero.

TORNADOES: A tornado or two may occur tonight over parts of the

Florida Peninsula and southern Alabama. The risk of tornadoes will

increase on Thursday, expanding northward across Florida into parts

of Georgia and South Carolina.

SURF: Swells generated by Helene will affect the southern coast of

Cuba and the Yucatan Peninsula of Mexico during the next couple of

days. Swells will spread northward toward the west coast of Florida

and the northeastern Gulf Coast later today and Thursday. These

swells are likely to cause life-threatening surf and rip current

conditions. Please consult products from your local weather office.

Operation Stormwatch Macon