In the days before Hurricane Milton hit Florida, forecasters were worried it could send as much as 15 feet (4.5 meters) of water rushing onto the heavily populated shores of Tampa Bay.
Instead, several feet of water temporarily drained away.
Why? ''Reverse storm surge'' is a familiar, if sometimes unremarked-upon, function of how hurricane winds move seawater as the storms hit land — in fact, it has happened in Tampa Bay before.
In the Northern Hemisphere, tropical storm winds blow counterclockwise. At landfall, the spinning wind pushes water onshore on one end of the eye and offshore on the other. Picture drawing a circle that crosses a line, and see how the pencil moves toward the line at one point and away at another.
The most pronounced water movement is under the strong winds of the eyewall, explains Brian McNoldy, a University of Miami senior researcher on tropical storms.
Milton's path toward the central part of Florida's west coast was clear for days, raising the possibility that Tampa Bay could bear the brunt of the surge. But it is always tricky to predict exactly where landfall will happen — and when, which can be important because a daily high tide can accentuate a surge.
To be sure, hazardous wind, rain and some degree of surge can happen far from the center. But the exact location of landfall makes a big difference in where a surge peaks, McNoldy said. Same goes for a reverse, or ''negative,'' surge.
Ultimately, the center of east-northeastward-moving Milton made landfall Wednesday night at Siesta Key, near Sarasota. It is about 70 miles (112 kilometers) south of the city of Tampa.
