What is storm surge? What are its impacts? Is Florida at risk? Your questions answered

As Tropical Storm Ian snakes toward the Sunshine State, officials worry about a potentially dangerous storm surge along the west coast of Florida and the panhandle.

Ian has slowly organized and is expected to evolve into a hurricane by Monday. On Tuesday, Ian may be a Category 4 storm with 130 mph winds, ready to cut through Cuba. The following day, it plans to traverse into the Gulf of Mexico, before deciding where to head next.

As it moves around, Ian will leave many regions feeling its wrath, notably through storm surges. Here’s what you need to know about storm surge and its risks to Florida.

What is storm surge?

Storm surge occurs when there’s a departure from normal tide levels, said Pablo Santos, a meteorologist at the National Weather Service in Miami.

“Whatever amount of water you end up with, that is above or beyond the regular tide is storm surge,” Santos said.

A storm’s intensity, its wind field and the topography of the coast all affect the severity of the rise in water, Santos said. Over time, winds push water toward the coast, which causes flooding.

And a slowing storm — like Tropical Storm Ian — can be a problem.

“A storm that is moving very slowly as it’s approaching the coast, has more time to keep pushing the water further inland as it’s crossing the coast,” he said.

Does storm surge happen when the storm nears the coast?

A storm can generate significant storm surge from afar, Santos said. Especially in areas similar to the Gulf of Mexico, which is almost like an enclosed space.

“You can have the storm moving well offshore... and generating a significant storm surge,” he said.

The shape of Florida’s coast doesn’t help either, he said. With a hurricane moving parallel to the coast, the water ends up getting trapped and amplifies the effects of storm surge.

And with these existing concerns, Ian is also forecast to strengthen into a major hurricane and to expand considerably as it moves into the Gulf, Santos said.

“Those are prime ingredients... to get a significant amount of storm surge,” he said.

How will Florida be affected by storm surge?

Santos suspects Florida’s west coast will be impacted to varying degrees. But it’s still too early to tell what areas will be the most affected.

Florida’s west coast is uniquely vulnerable to storm surge. The shallow shelf in the Gulf of Mexico can push tremendous amounts of water onshore.

“Those areas where the coastal topography is very shallow, they’re more prone for surge,” Santos said.

Acting NHC Director Jamie Rhome said the region had “perhaps some of the highest vulnerability in the country” to storm surge.

“I’m telling you it doesn’t take an onshore or a direct hit from a hurricane to pile up the water,” he said. “We could see a significant amount of storm surge on the west coast of Florida even if the storm stays offshore.”

Coastal Emergency Risks Assessment, a map created by Louisiana State University that delivers storm surge guidance, predicts there will be hotspots near Tampa and much of the north-central coast of the state later into the week.

READ MORE: Tropical Storm Ian primed to power up, hit Florida as hurricane. Exact track uncertain

What do I do if there’s storm surge in my area?

If you live in an area that is storm surge-prone, stay informed and follow the advice of local emergency management. You might be ordered to evacuate.

You should know your zone to stay updated on if you need to evacuate. You can identify your zone by inputting your address into this map.

“If you’re living in an evacuation zone and they place you under mandatory evacuation, you should heed that and comply,” Santos said. “Because literally, your life is at risk.”