Now, having weakened to a tropical storm, Michael was on its way to the Carolinas. The storm is expected to make landfall by early afternoon.
More than 900,000 homes and businesses in Florida, Alabama, Georgia and the Carolinas have been left without power.
Long said many Florida buildings were not built to withstand a storm above the strength of a Category 3 hurricane on the five-level Saffir-Simpson Hurricane Wind Scale. That's about 480 miles (770 km) southwest of the southernmost Cabo Verde Islands.
The latest Area Forecast Discussion for Jacksonville Courtesy of the National Weather Service.
"There are so many downed power lines and trees that it's nearly impossible to get through the city", Apalachicola Mayor Van Johnson said.
Authorities are preparing to set up extra shelters and move people into more secure areas. Outside, she said in a phone interview, she could see remnants of people's lives strewn about: refrigerators, a beanbag chair, a washing machine, a kayak and a dresser. "This storm surge is coming with a vengeance".
Patricia Mulligan said she survived Hurricane Andrew in 1992, only to encounter the wrath of another storm Wednesday. "There's nothing left here anymore". Graham said storm surge will inundate the Aucilla River there to a point where it will "flow backward". "I don't think anyone would have experienced this in the Panhandle", meteorologist Ryan Maue of weathermodels.com told The Associated Press.
Michael also disrupted energy operations in the U.S. Gulf of Mexico as it approached land, cutting crude oil production by more than 40 percent and natural gas output by almost one-third as offshore platforms were evacuated.
In Panama City, about 20 miles northwest of Mexico Beach, the power went out at Country Inn Suites. A light pole toppled onto an SUV in the parking lot. She and her daughter booked a hotel room through Friday.
"I've never seen anything like this ..."
Mulligan and her family rode out Hurricane Michael in their Mexico Beach condo.
Rick Scott, the Florida governor, said there had been "unimaginable destruction".
"The center of Michael will continue to move over the southern Gulf of Mexico this morning, then move across the eastern Gulf of Mexico later today and tonight", the agency said.
Gale and James Berry fled to a city shelter in Lincoln High School's cafeteria.
Scott, who expressed frustration about people dismissing evacuation orders on Tuesday as Michael rapidly grew into a Category 4 storm, told evacuees not to return home as roads remain closed by flooding, downed trees, and power lines.
Vance Beu, 29, was staying with his mother at her home, Spring Gate Apartments, a complex of single-story wood frame buildings where they piled up mattresses around themselves for protection.
"Tropical storm wind gusts will continue across much of SC and central and eastern North Carolina, with sustained tropical storm force winds expected along the coast of the Carolinas", the agency said.
He also became the first major hurricane of category 3 or higher that hit Florida after hurricane Dennis in 2005. Downgraded to a tropical storm over south Georgia, it was weakening by the hour.
Michael, the third most powerful storm ever to strike the USA mainland, weakened into a tropical storm over SC.