Idalia is forecast to strengthen rapidly as it moves north into the Gulf of Mexico and closes in on the west coast of Florida, and will likely be a major, Category 3 hurricane as it makes landfall, forecasters said Monday.

“Idalia is poised to rapidly intensify today-tomorrow, meaning it can go from a tropical storm to a very dangerous hurricane within the next couple of days,” said Brian McNoldy, a senior research associate at the Rosenstiel School of Marine, Atmospheric and Earth Science at the University of Miami, in a Monday morning post on X, the site formerly known as Twitter.

“Plan to have preparations completed by the time tropical storm conditions arrive, and plan to evacuate if told to,” he said.

What is rapid intensification?

Rapid intensification is a process in which a storm undergoes accelerated growth: The phenomenon is typically defined to be a tropical cyclone (whether a tropical storm or hurricane) intensifying by at least 35 mph in a 24-hour period.

“Rapid intensification occurs when a tropical storm or hurricane encounters an extremely conducive environment,” Colorado State University hurricane researcher Phil Klotzbach said last year. “Typically, this environment consists of very warm water, low vertical wind shear and high levels of midlevel moisture.”

Such sudden spikes have been the hallmark of history’s most fearsome hurricanes, Ken Graham, former director of the National Hurricane Center and now director of the National Weather Service, told USA TODAY.

In fact, out of the 10 hurricanes with winds of 150 mph or greater that struck the U.S. mainland over 104 years, all but one saw the explosion of force and power known as rapid intensification.

Hurricane Ian had two such bursts of wind last September, reaching winds of 155 mph briefly before it made landfall on Florida’s southwest coast.

What does the National Hurricane Center say about Idalia?

In its 11 a.m. forecast discussion for Idalia, the National Hurricane Center said, “steady to rapid intensification is predicted beginning Tuesday while Idalia traverses the warm waters of the eastern Gulf and the upper-level environment becomes more favorable.

“The NHC intensity forecast again calls for Idalia to reach major hurricane strength before landfall along the Gulf coast of Florida,” the hurricane center said.