▶ Watch Video: Most of Florida under state of emergency with Hurricane Idalia less than a day away

Hurricane Idalia is gaining strength as it moves toward Florida, where residents are scrambling to prepare for the impacts of what is forecast to be a major storm. Idalia is expected to grow into an extremely dangerous hurricane before it makes landfall on Florida’s Gulf Coast on Wednesday, according to the National Hurricane Center.

“Life-threatening” storm surge and hurricane conditions are expected along parts of the Gulf Coast Tuesday night and Wednesday, the hurricane center said

Florida Gov. Ron DeSantis has declared a state of emergency covering 46 counties. Evacuation notices have been issued in 21 counties, with mandatory orders in effect for some people in eight of them, The Associated Press reports. 

“You still have time this morning to make your final preparations,” DeSantis said, “but you gotta do that now.”

“You do not have to leave the state. You don’t have to drive hundreds of miles,” he said. “You have to get to higher ground in a safe structure. You can ride the storm out there, then go back to your home.”

Tolls were suspended early Tuesday morning along Florida’s west coast, according to the governor’s office, and shelters are open.

Schools across more than three dozen Florida counties are also closed this week. Many will be shuttered at least through Wednesday, according to the Florida Department of Education

Hurricane path and map 

Hurricane Idalia was in the Gulf of Mexico Tuesday moving north at 14 mph. About half of the Idalia models published by the National Hurricane Center project it will make landfall in Florida’s Big Bend area, which is where the panhandle meets the peninsula, and which includes Tampa Bay, according to CBS News senior weather and climate producer David Parkinson.

The storm could arrive on Wednesday morning between 7 a.m. and 11 a.m. ET, Parkinson said. 

Hurricane maps show the projected path of the storm and its impacts.

National Weather Service

What category of storm will Hurricane Idalia be?

Hurricane Idalia is forecast to strengthen into at least a Category 3 hurricane.

“This is going to be a major impact,” DeSantis said at a news conference Monday. “And Floridians should expect that this storm will be a major Cat 3+ hurricane, so please prepare accordingly.”

Category 3 storms have sustained wind speeds of 111-129 mph and are expected to produce devastating damage, including downed trees, major damage to homes and days- or weeks-long cuts to electricity and water, the hurricane center says. 

A Category 3 storm — like a Category 4 or 5 — is considered a “major” hurricane due to the potential for “significant loss of life and damage,” the National Hurricane Center says. 

Hurricane watches and warnings are in effect for parts of Florida’s Gulf Coast as the storm is strengthening. 

State of emergency in effect 

DeSantis expanded a state of emergency to cover 46 Florida counties. He first issued a state of emergency on Saturday for 33 of the state’s 67 counties to ensure communities “have time to prepare for the storm system which could have impacts along the Gulf Coast next week.”

His office said over the weekend the Florida National Guard was mobilizing 1,100 personnel to support areas of the state that are impacted. Additionally, 12 aircraft and 2,400 high wheel vehicles were being mobilized.

Parts of Florida’s west coast and the Florida Panhandle — as well as southeast Georgia and the eastern Carolinas — could see up to 8 inches of rainfall from Tuesday through Thursday, with up to 12 inches possible mostly in areas near where the storm makes landfall, the National Hurricane Center says. That could lead to flash and urban flooding, “some of which may be locally significant.”

Storm surge is also expected. The water level could reach as high as 15 feet in the area between the Aucilla River and Yankeetown, Florida, if storm surge coincides with high tides. It could reach as high as 11 feet in other areas, and 7 feet in Tampa Bay, according to the hurricane center. 

What is storm surge?

Storm surge is “an abnormal rise of water generated by a storm,” according to the National Hurricane Center. As a storm moves toward the coast, water is pushed to the shore and “piles up,” which creates a surge. 

If a storm surge and high tide take place at the same time, water levels will be even higher. The combination is known as storm tide. 

Storm surge is one of the deadliest hazards of a hurricane. It is also “a very complex phenomenon,” according to the hurricane center,” because it depends on factors including a storm’s wind speeds, size and angle of approach to the coastline, as well as the shape and characteristics of the coast.

A storm surge warning is in effect for Englewood north to Indian Pass, Florida. A storm surge watch is in effect for Chokoloskee to Englewood, including Charlotte Harbour, as well as for the mouth of the St. Mary’s River to South Santee River, South Carolina.

Nicole Brown Chau contributed to this report.