Hurricane Florence could bring catastrophic storm surges: What are they, and how can you prepare?

Once designated a Category 4, Hurricane Florence is poised to make landfall on the coast of the Carolinas Friday morning as a still dangerous Category 1 storm, bringing with it potentially catastrophic storm surges.

A storm surge warning means “there is a possibility of life-threatening inundation, from rising water moving inland from the coastline, in the indicated locations,” the NHC said in an advisory.

“Storm surges in general used to be a leading cause of fatality with hurricanes, but now – because of evacuations and getting the word out so far in advance – [the number of deaths] has gone down,” Joel Cline, a tropical program coordinator with the National Weather Service deployed to the Carolinas for the storm, told Fox News. “But [storm surges] still remain to be the potential largest loss of life from a hurricane.”

Read on for a look at what causes surges and some ways to prepare if you’re in the projected path of Hurricane Florence.

What are storm surges?

A storm surge is “the abnormal rise in seawater level during a storm,” according to the National Ocean Service. It’s measured by how high the water reaches from the normal astronomical tide.


Surges are caused by winds from a storm pushing water toward the shore, according to the National Ocean Service. They can cause catastrophic damage and flooding, toppling houses and destroying roads.

Storm Tide NOAA

A storm surge is “the abnormal rise in seawater level during a storm,” the National Ocean Service says.  (National Ocean Service)

"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 NHC said. 

Storm surges are different from storm tides, which refers to the rise in water levels due to the astronomical tide combined with storm surges.

What are some tips to prepare?

The best way to prepare for storm surges is to evacuate, Cline said.

“You really can’t run away from the winds of a hurricane, but you can avoid the water,” Cline said.


He warned those in the storm’s path that “alleviation [from storm surges] to property is likely not going to happen in these instances.” To prepare, he said people should put important documents in waterproof bags as they plan to evacuate to a safer area.

He also stressed the importance for residents to make sure to follow other hurricane preparation advice, including having fresh water, batteries, battery-powered radios, propane, flashlights, canned food and handheld can openers on hand.

What can we expect from Florence?

Ahead of Florence’s arrival, barrier islands were already seeing dangerous rip currents and seawater flowing over a state highway – the harbinger of a storm surge that could wipe out dunes and submerge entire communities.

In North Carolina particularly, the barrier islands of the Outer Banks only leave a few inlets for water to be let out once the heavy rainfall and storm surges push water inland – further intensifying the impact of flooding in the area, Cline said.


Storm surges could be as high as 11 feet along the 80 miles of the North Carolina coast between Cape Fear and Cape Lookout, the NHC warned Friday. Additionally, they could reach up to 9 feet between Cape Lookout and the Ocracoke Inlet in North Carolina.

"The deepest water will occur along the immediate coast in areas of onshore winds, where the surge will be accompanied by large and destructive waves," the NHC said. "Surge-related flooding depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances."

The Associated Press contributed to this report.

Kaitlyn Schallhorn is a Reporter for Fox News. Follow her on Twitter: @K_Schallhorn.

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