'Reverse storm surge': How Hurricane Milton could flood Tampa Bay or shockingly dry it

As Category 3 Hurricane Milton neared Florida's west coast Wednesday, the Tampa Bay area faced two scenarios — either a colossal storm surge and historic flooding or seeing the water blown out of the Bay.

The first scenario, — 10 to 15 feet of water — would have been a disaster of epic proportions. The second option, called a "reverse" storm surge, can expose sand, silt, and debris typically covered by water. It is a strange phenomenon that occurs with the circular winds of a hurricane.

Because Milton roared ashore with its center of circulation just a little over 20 miles to the south, the especially vulnerable Tampa Bay narrowly averted the most catastrophic storm surge. While water rocketed higher at tide gauges along the coast south of Siesta Key and Sarasota as Milton roared ashore Wednesday evening, gauges plunged around the Bay.

State officials warned residents to avoid stepping onto any bare ground because the water was expected to roar back as Milton's winds shifted.

When the water flowed back, it was expected to rise higher, but not in the proportions that would have occurred if the center moved over Tampa Bay or just to the north, said Tyler Fleming, a National Weather Service meteorologist.

Farther south along the coast and some inland waterways, communities such as Fort Myers and Naples experienced flooding as the water rose sharply. In some cases, the water rose by 4 to 8 feet, and officials said that could continue into the early Thursday.

What is reverse storm surge?

Storm surge happens as a tropical storm or hurricane pushes water toward the coast, triggering catastrophic flooding along the shore, and in bays and inlets.

It happened in Florida during Hurricanes Irma and Ian, said WeatherTiger meteorologist Ryan Truchelut.

With reverse storm surge, especially in larger storms, the opposite happens, explained AccuWeather meteorologist Paul Pastelok in 2022, after Ian hit. “It can pull the water out because the wind flow is coming from land to ocean, and it pushes the water,” he said. “The power of the wind is incredible.”

The result is bare ground in some places, particularly along the shoreline, according to Pastelok.

The phenomenon can occur during any hurricane, whether it makes landfall along the eastern U.S. coast or in the Gulf, according to the National Weather Service office in the Tampa Bay area.

Why does it happen?

Storm surge can happen near and to the right of where a storm makes landfall, but negative water levels can occur to the left of the landfall location, said weather service meteorologist Ernie Jillson in 2022. Tampa Bay was on the left side of where Ian made landfall as its winds blew from the northeast, he said.

It depends on the shape of the waterway, and bays are more susceptible because they're like a bowl of water,” Jillson told USA TODAY. “They're protected by land on all sides except one, so that's why they're so susceptible to being emptied out.”

How dramatic the phenomenon appears depends on the storm's intensity, according to Pastelok.

'Like a bathtub let the water out'

When reverse storm surge hit Florida during Hurricane Ian in 2022, one resident said of a waterless Ochlockonee Bay, "It was just like a bathtub let the water out," Donna Bourgeois said. "Just, it was gone."

On Twitter, now X, Tammy Young wrote, "The fact that all the water disappears from #tampabay before the storm comes is mind blowing."

In St. Marks, Florida, Kathleen Spehar said, "If the sea became a desert, what would it be like? That was the feeling of being out there," she said. "It was beautiful, blue clouds, yet desolate."

"It was a little bit creepy that the storm was so powerful that it could suck up and dry out that entire bay area," she added.

Contributing: Ashley R. Williams, USA TODAY; Ana Gon?i-Lessan, Tallahassee Democrat

This article originally appeared on USA TODAY: Could Hurricane Milton cause 'reverse storm surge' in Tampa Bay?