Tampa Bay, recognized as the U.S.’s most at-risk metro area for storm surge, might experience its most severe flooding in 100 years if the most alarming forecasts regarding Hurricane Milton’s trajectory prove correct.

With predictions indicating flooding of 8 to 12 feet of seawater in the Tampa Bay region, this represents the “highest storm surge prediction ever specifically given by the National Hurricane Center for Tampa Bay,” stated Michael Lowry, a hurricane expert at WPLG Local 10 in Miami.

As the storm drew near on Monday, evacuations commenced in the Tampa metropolitan area, home to about 3.5 million residents, primarily due to the risks associated with storm surge. “Historically, storm surge has been the most lethal danger presented by hurricanes, accounting for over half of hurricane-related fatalities in the last 50 years, and is the main cause for pre-storm evacuations,” commented Lowry.

Most at-risk metropolitan area in the nation

A 2015 analysis by Karen Clark & Company, a risk assessment organization, revealed that the Tampa-St. Petersburg metropolitan area is the nation’s most vulnerable to the dangers of storm surge.

This report estimated that a Category 4 hurricane making landfall just north of Tampa Bay could result in $230 billion in damages (in 2024 dollars) purely from storm surge effects, according to meteorologist Jeff Masters on the Yale Climate Connections blog.

Why is Tampa particularly prone to storm surge?

There are multiple factors that make Tampa the most susceptible U.S. city to storm surge, as outlined in the 2015 report:

Firstly, the continental shelf off Florida’s west coast is relatively broad. The extensive shallow waters, less than 300 feet deep extending up to 90 miles offshore, allow significant storm surges to develop, according to Masters.

This condition heightens the sea level rise associated with a major hurricane.

Secondly, Tampa Bay functions as a large funnel — particularly when a hurricane with strong winds approaches the bay’s entrance, as noted in the report.

“A powerful storm with the appropriate path will cause a massive accumulation of water that could become trapped in the bay, inundating large areas of Tampa and St. Petersburg. Approximately fifty percent of the local population resides at elevations below ten feet,” the report highlights.

The 1921 hurricane as a reference point

Tampa has not suffered a direct impact from a major hurricane since the one in 1921; that storm was barely a Category 3 hurricane, according to the report.

As noted by Yale Climate Connections, the last significant hurricane to strike the Tampa Bay region was on October 25, 1921. “This low-end Category 3 storm, with winds reaching 115 mph upon landfall, triggered a storm tide of 10-11.5 feet, causing extensive destruction (equivalent to $180 million in 2024 calculations).”

Although Hurricane Charley was on course for Tampa in 2004, it unexpectedly veered south just before reaching land, as mentioned in the Karen Clark report.

The uncertainty in forecasts

The path of Milton is crucial in determining where the most significant storm surge will make landfall, Lowry explained. As of Monday afternoon, much of Florida’s west coast, including the entire Tampa Bay area, was in the hurricane center’s “cone of uncertainty.”

However, the current forecast is still not definitive.

Unfortunately, there is an average forecast error of 20-40 miles even as close as 12 to 24 hours before landfall. Florida’s unique geography often exacerbates these common errors, making it challenging to pinpoint where the worst storm surge may occur, Lowry added.