Storm-surge flooding surrounded the Superdome in New Orleans after Hurricane...

Storm-surge flooding surrounded the Superdome in New Orleans after Hurricane Katrina. (Sept. 3, 2005) Credit: KRT

WASHINGTON -- More than 1.8 million homes along the Gulf and Atlantic coasts, including Long Island, are at great risk of being damaged by a hurricane, three times the number located in federally defined flood zones, according to a report released Tuesday.

The report by CoreLogic, a private real estate data firm, focused on the potential impact of storm surge, which is the indirect damage from water and flying debris triggered by strong winds. Roughly two-thirds of the homes cited in the report are located outside Federal Emergency Management Agency flood zones.

Storm surge can cause extensive damage when seawater breaks through structures and carries debris with it. That's what happened in New Orleans in 2005, when storm surge from Hurricane Katrina broke the levee system and flooded most of the city and surrounding parishes.

The homes most at risk are concentrated in Virginia Beach, Va., New Orleans, Tampa, Long Island and Miami. The report examined the exposure of a single home to storm surge in 10 U.S. metro areas. It used computerized models, which generated the probability of a hurricane hitting a particular area, residential density rates, elevation, levees and barriers and water depths along those coastal areas.

The report also looked at the damage caused by a storm's direct impact. Florida and Texas are the states most vulnerable to a direct hit. Corpus Christi, Galveston and Houston and Jacksonville, Miami, Palm Beach and Tampa were cited as facing the greatest risk in those states.

The areas potentially most affected by a Category 5 hurricane, the highest category storm with wind gusts of at least 156 mph, include the waterside resort city of League City, Texas, near Houston; the Palmetto and Perrine sections of south Miami, near Biscayne Bay; and the Tampa suburb of Port Richey.

Over the past decade, eight Category 5 hurricanes have made landfall from the Atlantic Ocean, Caribbean Sea and Gulf of Mexico. The last one to hit was Hurricane Felix in September 2007, which left more than $700 million in damage and killed 133 people, mostly in Nicaragua.

New Orleans fared better this year than Florida and Texas, largely due to the city's efforts to rebuild levees and flood walls and install other "100-year" storm protections following Hurricane Katrina. But New Orleans, which sits mostly below sea level on the east bank of the Mississippi River and south of Lake Pontchartrain, is still listed as having a "high" probability for a hurricane.

Researchers at Colorado State University say there is a 72 percent chance that one major hurricane will hit the U.S. coast this year. Storm season in the Atlantic region lasts from June to November.

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