CRAWFORDVILLE, United States (AFP) – Parts of Florida face “unsurvivable” conditions when Hurricane Helene hits later Thursday, the US weather service said, warning that howling wind will drive destructive waves and storm surge as high as 20 feet (six meters) onto the low-lying coast.

Residents heeded mass evacuation orders and fled ahead of the incoming hurricane — projected to be one of the largest Gulf of Mexico storms in decades.

The fast-moving and intensifying storm was at Category 2 mid-day Thursday, the National Hurricane Center (NHC) in Miami said, packing wind speeds of 105 miles (169 kilometers) an hour as it churned over the gulf’s warm waters.

The NHC said Helene is expected to make landfall at or near Florida’s Big Bend coast in the evening as a major Category 3 and possibly even Category 4 storm.

The hurricane center minced no words on X, saying: “EVERYONE along the Florida Big Bend coast is at risk of potentially catastrophic storm surge.”

Tampa and Tallahassee airports have already closed, and Florida Governor Ron DeSantis urged residents to rush final preparations ahead of the storm.

It’s a “very dangerous hurricane,” NHC director Mike Brennan said.

“We’re expecting to see a storm surge inundation of 15 to 20 feet (4.5-six meters) above ground level,” he said. “That’s up to the top of a second story building. Again, a really unsurvivable scenario is going to play out here in this portion of the Florida coastline.”

The accompanying waves “can destroy houses, move cars, and that water level is going to rise very quickly,” Brennan added.

Despite the dire forecast Patrick Riickert refused to evacuate from his small wooden house in Crawfordville, a town of 5,000 people halfway between Tallahassee and the coast — and that will almost certainly be walloped by Helene.

Most of the town has bolted, but he and his wife and five grandchildren are “not going anywhere,” the 58-year-old told AFP.

“I am going to hunker down” and ride out the hurricane, as he did in 2018 when deadly Hurricane Michael, a Category 5 megastorm, blew through the Florida panhandle.

“I trust in my faith that God is going to keep me safe,” he added.

The NHC warned of up to 20 inches (51 cm) of rain in isolated spots inland, and potentially life-threatening flooding as well as “numerous” landslides across the southern Appalachians.

Several states are in the potential path and were already getting battered by high winds and heavy rain. Floodwaters in cities around Tampa Bay have made roads impassable, local media showed.

The risk of tornadoes was increasing across northern Florida, Georgia and the Carolinas.

Georgia’s capital Atlanta, a metropolis of some five million people, is forecast to experience tropical storm-force winds and as much as 12 inches (30.5 cm) of rainfall, which authorities warn could bring flash flooding.

Most of Georgia, which like Florida is under a state of emergency, was placed on flood watch, while Tennessee — more than 300 miles from the Gulf Coast — braced for tropical storm conditions statewide.

“This is going to be a multi-state event with the potential for significant impacts from Florida all the way to Tennessee,” Federal Emergency Management Agency administrator Deanne Criswell told reporters at the White House after she updated President Joe Biden on the situation.

“The president wants to make sure that everyone is paying attention to the potential life-threatening impacts that this storm may bring,” she said.

Florida governor Ron DeSantis mobilized the National Guard and positioned thousands of personnel to prepare for search and rescue operations and power restoration.

A direct impact was likely in the Tallahassee region, where coastal communities now look like ghost towns.

Helene could become the most powerful hurricane to hit the United States in over a year — and almost certainly the biggest.

Hurricane specialist Michael Lowry called Helene “extreme,” noting the breadth of its tropical storm winds of 39 mph or higher stretch nearly 500 miles across.

Category 3 Hurricane Idalia hit northwestern Florida in August 2023.

Researchers say climate change likely plays a role in the rapid intensification of storms, because there is more energy in a warmer ocean for them to feed on.