Hurricane Milton strengthened to a major Category 4 storm early Monday, driving sustained winds of 150 mph as it rolled across the Gulf of Mexico bound for what could be a devastating crash along Florida's already storm-battered western coast.

The storm has rapidly intensified, strengthening from a Category 2 storm in a couple hours. The National Hurricane Center has issued hurricane watches across portions of Florida and warned that parts of the state could be overwhelmed by life-threatening storm surge, flooding rain and damaging winds.

Milton is forecast to remain an "extremely dangerous" hurricane of at least Category 4 strength for the next couple of days. A Category 4 hurricane features sustained winds of 130-156 mph. Some weakening is then forecast before the hurricane reaches the coast, but Milton "is still likely to be a large and powerful hurricane at landfall in Florida," hurricane center specialist Jack Beven wrote in an advisory.

Rainfall is expected to total 5-10 inches in some areas of the state that were saturated even before Hurricane Helene smashed ashore less than two weeks ago. Isolated communities could see 15 inches, the hurricane center said. What could be a deadly storm surge of 8-12 feet is possible for more than 200 miles of coastline − with Tampa in the middle.

"The track guidance is in good agreement that the hurricane will cross the Florida Peninsula, but there remains significant differences in both the location and timing of landfall," Beven wrote.

Developments:

∎ Milton was centered 745 miles west-southwest of Tampa early Monday, moving east-southeast at 8 mph.

∎ Mexico has issued a Hurricane Warning for the coast of the Yucatan Peninsula from Celestun to Rio Lagartos.

Hurricane Milton tracker: Follow projected path of Category 3 storm expected to hit Florida

Pinellas, Manatee and Sarasota were among counties expected to announce evacuation orders Monday. Pinellas County, which includes the city of St. Petersburg, was planning to announce mandatory evacuations for 500,000 people in the low-lying areas, Sheriff Bob Gualtieri said Sunday. He urged people to heed evacuation orders after he said too many ignored them for Helene, resulting in 12 deaths in the county and 1,500 emergency calls that went unanswered.

The county already ordered the evacuation of six hospitals, 25 nursing homes and 44 assisted living facilities totaling 6,600 patients, said Cathie Perkins, director of the county's emergency management. School was canceled through Wednesday.

Kevin Guthrie, director of Florida's emergency management division, said the state was preparing for the largest evacuation since Hurricane Irma in 2017, when more than 6 million Floridians were forced to flee their homes.

Gov. Ron DeSantis has declared a state of emergency for 51 of Florida's 67 counties ahead of Milton. Declaring a state of emergency allows the state and local governments more freedom to coordinate emergency agencies and relax restrictions.

The governor may suspend regulations that would slow emergency response, commandeer private property needed to deal with the emergency, order evacuations and direct or delegate control of the National Guard to help rescue or cleanup operations. DeSantis also could suspend the sale of alcohol, guns, explosives and combustibles, establish emergency housing, limit power services as needed, and impose or allow exceptions to curfews. Read more here.

− C. A. Bridges, USA TODAY NETWORK - Florida

Contributing: Reuters