“Rapid strengthening is expected during the next day or so, and Ian is forecast to become a major hurricane (Monday night) or early Tuesday when it is near western Cuba and remain a major hurricane over the southeastern Gulf of Mexico on Wednesday,” the hurricane center said.

Forecasters predict by the time Ian makes landfall in the US this week, it could be a major hurricane – with winds reaching 111 mph or greater.

While projection models show a wide range of possible paths, one fear is evident: Tampa, on western side of Florida, could get its first direct hit from a hurricane since 1921.

And that could be devastating.

“The last major hurricane that actually made a direct hit was 100 years ago,” said meteorologist Rick Davis of the National Weather Service’s Tampa office. “So there’s a lot of people that have been brushed by hurricanes in the last five or 10 years in Florida.”

And Tampa doesn’t even need a direct hit to see catastrophic damage from flooding. Tampa Bay is extremely vulnerable to storm surge because water being pushed into it has nowhere to go.

“So it just continues to pile water in into downtown Tampa, which is very vulnerable to storm surge flooding,” Davis said.

“We tell people even if they’re lifelong Floridians like myself, this is something that we haven’t seen in our lifetime,” Davis said. “So we definitely need to take it seriously.”

MacDill Air Force Base has issued an “installation-wide mandatory evacuation” by noon Tuesday for “non-mission essential individuals, including uniformed service members” and dependents, the base tweeted Monday. The base has about 6,000 military and civilian personnel, its website says.

A mandatory evacuation order has also been issued for Zone A of Hillsborough County, Florida, as of 2 p.m. ET Monday, the county administrator said Monday. And a voluntary evacuation has been recommended for Zone B, administrator Bonnie Wise said, adding emergency shelters are also being opened.