Gov. Scott warns of storm surge

Hurricane could pile water 15 feet higher than normal, blow it on land

MIAMI - Life-threatening storm surge is expected for parts of Florida, especially if Hurricane Irma’s winds push seawater ashore at high tide.

“This will cover your house,” Gov. Rick Scott said Saturday. “It flows in fast, very fast. You will not survive all this storm surge.”

The National Hurricane Center forecast water levels up to 15 feet above ground for the Florida Keys island chain and parts of the state’s Gulf coast, along with up to 25 inches of rain in the Keys.

The flooding threat extended far beyond the path of Irma’s eye. The Atlantic coast from Miami to Isle of Palms, South Carolina, could see up to 6 feet of storm surge.

Miami-Dade County Mayor Carlos Gimenez said it was Irma’s storm surge threat, not fierce winds, that triggered evacuation orders for 660,000 people in the Miami area.

What is storm surge?

It’s not a wall of water or a tsunami. Simply put, hurricane winds push water toward shore. It can happen quickly and far from a storm’s center, inundating areas that don’t typically flood.

The flooding risk will not drop just because Irma’s winds might weaken, said Jamie Rhome, head of the hurricane center’s storm surge unit.

Large hurricanes tend to create greater storm surge over a broader area, and coastal features such as bays can act like funnels and back water up into rivers and canals, Rhome said.

“This is going to sneak up on people,” Rhome said.

What’s at risk?

About 1,000 miles of coastline from Tampa Bay to the mid-South Carolina coast could see storm surge. Much of that landscape lies less than 10 feet above sea level, and the surge from Irma could be a few inches higher in some areas.

Much of Florida’s southwest coast is uninhabited swampland, including a large section of Everglades National Park.

North of the Everglades lies Naples, an upscale town of about 22,000 that is also the home of the Florida governor.

The hurricane center’s storm surge maps, showing deep inundation for Naples, worried Colorado State University hurricane researcher Phil Klotzbach.

“Look at Naples, the entire town of Naples is underwater,” Klotzbach said.

Farther north is the Tampa Bay region, with about 3 million people, a Busch Gardens theme park and baseball spring training grounds.

Deadly waters

Storm surge has accounted for half the U.S. deaths from hurricanes, tropical storms and cyclones over the last halfcentury, according to a hurricane center study.

The surge helped destroy nearly half the structures along a 40-mile stretch of the Florida Keys during the 1935 Labor Day Hurricane, which killed more than 400 people, including World War I veterans working on a railway project.

Storm surge flooding up to 28 feet above normal tide levels were associated with Hurricane Katrina in 2005, directly or indirectly causing at least 1,500 deaths, according to the hurricane center.

Even tropical storms can cause major coastal flooding. Hurricane Sandy lost its tropical characteristics before making landfall in 2012, but its enormous size drove catastrophic storm surge onto the New Jersey and New York coastlines.