As Hurricane Milton approaches landfall in Florida this week, the National Hurricane Center is releasing a series of data sets to help warn the public of the risks. Storm surge is one of the deadliest aspects of a strong hurricane as it approaches land.
Depending on exactly where Milton makes landfall, storm surge will broadly fluctuate. As it approaches the Florida coast, any minor wobble in the storm’s path could vastly change where the worst surge piles up.
The area surrounding Cedar Key is still dealing with the effects of Hurricane Helene. For now, it appears residents there will be less impacted by Milton.
As the forecast path adjusts, Tampa continually seems like it will be in Milton’s direct path. The Tampa Bay area will most likely see large swells. Residents have been urged to evacuate.
The Fort Myers area was devastated by Hurricane Ian in 2022. This area is again forecast for a storm surge above six feet across large areas.
Naples and the Everglades will bear the brunt of the winds coming off the southern part of the storm.
The Florida Keys are forecast to experience strong winds and storm surge mostly below six feet.
The uncertainty of the storm surge’s eventual impacts is especially true for Tampa Bay.
If Milton tracks south of Tampa Bay, there could be far less surge there than during Hurricane Helene last month, said Robert Weisberg, a professor emeritus at the University of South Florida. His work as an oceanographer — including a 2006 study on storm surges in the Tampa Bay area — helped begin the conversation about the region’s vulnerabilities.
Dr. Weisberg said there is even the potential, if Milton is far enough south, for the storm to produce a reverse surge, as Ian did, pushing water out of the bay.
If the storm were to take a jog north, it would be a far more serious situation. “I hate to imagine what could happen if it does that,” he said.
If the storm were to make landfall near Clearwater, for example, the strongest winds along the eyewall could push the surge through the mouth of the bay.
The problem with the bay is that it is very long, Dr. Weisberg said, and the hurricane storm surge is really a slope with the highest amount of water piling up where it is pushed against the shore.
In a simplified example of a surge, if you were to blow across the top of a cup of water, you could see how it piled against the edge of the cup. This is similar to how water behaves in shallow places as wind whips across its surface.
Like the cup’s edge, water cannot penetrate the land. So as it drives water into the shoreline, it piles up.
If the storm makes landfall farther north, and those winds push up the bay, all of that water would be pushed right into Tampa, and the upper reaches of the bay would have a larger surge.
On top of the surge, come the waves, which can damage structures. “If people are in the way of the waves, they’re going to die. It’s as simple as that,” Dr. Weisberg said.
Wherever Milton makes landfall, storm surge will come ashore, especially just ahead and south of the storm’s center, similar again to what occurred during Ian.
As the storm moves inland, the wind will change direction, and since the slope of the sea surface changes with the wind, some portions of the bay will get inundated first, and then later, other portions of the bay will.
The surge is a complicated evolution based on the actual geometry of the body of water it encounters.
“That’s why you really can’t generalize a storm surge from one region to another,” Dr. Weisberg said.
Complicating factors with forecasting this surge will not only be the path the storm takes and its predicted irregular shape. But as the storm approaches landfall, it will most likely encounter turbulent air that will reduce the storm’s intensity but also make it less symmetric. So exactly what wind will blow where is unknown right now.
