In the days before Hurricane Milton In Florida, meteorologists feared that water could rise up to 15 feet (4.5 meters) onto the densely populated shores of Tampa Bay.

Instead, several meters of water temporarily flowed away.

Why? “Reverse storm surge” is a well-known, if sometimes ignored, feature of the way hurricane winds move seawater as the storms make landfall – in fact, this is the case happened in Tampa Bay before.

In the Northern Hemisphere, tropical storm force winds blow counterclockwise. When landing, the rotating wind pushes the water onto land at one end of the eye and into the sea at the other end. Imagine drawing a circle that intersects a line and see the pencil move toward the line at one point and away at another.

The most powerful water movement occurs under the strong eyewall winds, explains Brian McNoldy, a senior tropical storm researcher at the University of Miami.

Milton’s path to the central part of Florida’s west coast was clear for days, raising the possibility that Tampa Bay could bear the brunt of the flood. However, it is always difficult to predict exactly where and when landfall will occur, which can be important as a daily high tide can intensify a surge.

However, dangerous winds, rain and some degree of flooding can occur far from the center. But the exact location of landfall makes a big difference in where a surge peaks, McNoldy said. The same applies to a reverse or “negative” increase.

Ultimately, the center of the east-northeast-moving Milton made landfall at Siesta Key near Sarasota on Wednesday evening. It is located approximately 70 miles (112 kilometers) south of the city of Tampa.

That meant strong onshore winds caused a storm surge south of Siesta Key. The National Hurricane Center said Thursday that preliminary data showed waters rose 5 to 10 feet (1.5 to 3 meters) above the ground between Siesta Key and Fort Myers Beach.

In the meantime, the water level suddenly dropped by about 1.5 meters National Oceanic and Atmosphere Administration gauge near Tampa late Wednesday evening.

Hurricane Irma caused a similar effect in 2017. Ian also occurred in 2022 when people went out to see what was normally the ocean floor.

With any storm, “this is an extremely bad idea,” McNoldy says. “Because the water is coming back.”

In fact, water levels returned to normal on Thursday morning.