Hurricane Dorian to bring dangerous storm surge: What you need to know

PHOTO: A sign at the Lazaretto Creek boat ramp as is nearly underwater at high tide as Hurricane Dorian makes its way up the east coast, Sept. 4, 2019, toward Tybee Island, GaPlayStephen B. Morton/AP
WATCH Storm surges explained by Ginger Zee

Storm surge poses the biggest threat to people and property as Hurricane Dorian, a Category 1, charges up the coast.

Storm surge could reach 7 feet in North Carolina where Dorian made landfall on the Outer Banks Friday morning.

During Hurricane Katrina in 2005, at least 1,500 people died "directly, or indirectly, as a result of storm surge," the National Hurricane Center said.

But what is storm surge?

Here's how it works:

As pressure falls in the hurricane's center, water levels rise. The water accumulates while the storm is still over the open ocean.

When the hurricane closes in on land, its strong winds push that water toward the coast and up onto land, creating walls of water sometimes as high as 20 feet.

PHOTO: In this file photo, a car sits abandoned in storm surge along North Fort Lauderdale Beach Boulevard as Hurricane Irma hits the southern part of the state, Sept. 10, 2017, in Fort Lauderdale, Fla. Chip Somodevilla/Getty Images, FILE
In this file photo, a car sits abandoned in storm surge along North Fort Lauderdale Beach Boulevard as Hurricane Irma hits the southern part of the state, Sept. 10, 2017, in Fort Lauderdale, Fla.
PHOTO: In this file photo, a 3-story condominium has collapsed after Hurricane Irma send a storm surge and eroded the building foundations, in Islamorada, Florida Keys, Sept. 12, 2017. Marcus Yam/Los Angeles Times via Getty Images, FILE
In this file photo, a 3-story condominium has collapsed after Hurricane Irma send a storm surge and eroded the building foundations, in Islamorada, Florida Keys, Sept. 12, 2017.

The danger to people inside houses on the coast is the deluge of water that can flood homes and overpower walls rapidly.

When Hurricane Sandy hit New York and New Jersey in 2012, many homes filled quickly with water that reached levels of 8 to 9 feet.

The risks can be even greater if storm surge combines with high tide, creating a devastating, rapid rise in water levels.

PHOTO: In this file photo, storm surge hits a small tree as winds from Hurricane Sandy reach Seaside Park in Bridgeport, Conn., Oct. 29, 2012. Jessica Hill/AP, FILE
In this file photo, storm surge hits a small tree as winds from Hurricane Sandy reach Seaside Park in Bridgeport, Conn., Oct. 29, 2012.