Supercharged by abnormally warm waters of the Gulf of Mexico, the Category 4 storm crashed ashore in the early afternoon near Mexico Beach, a tourist town about midway along the Panhandle, a 200-mile (320-kilometre) stretch of white-sand beach resorts, fishing towns and military bases.
Forecasters anticipate Michael will reach land either in the Panhandle or somewhere along the state's Big Bend as soon as Wednesday morning.
Its center is located 200 miles south southwest of Apalachicola and 225 miles south of Panama City. The storm's center is expected to move inland over the Florida Panhandle or Florida Big Bend area before moving northeastward across the Southeastern U.S.
While Florence took five days between the time it turned into a hurricane and the moment it blew ashore in the Carolinas, Michael gave Florida what could amount to just two days' notice.
NHC forecasters said "On the forecast track, the center of Michael will move across the eastern Gulf of Mexico through tonight".
Smith, in Gadsden County, said the situation was risky even for emergency personnel.
"Oh my God, what are we seeing?" said evacuee Rachel Franklin, her mouth hanging open.
Smith could not provide details on the victim. He said people will "not be dragged out of their homes", but anyone who stays behind will be on their own once the storm hits.
"It really started as a tropical storm, and then it went to Category 1, then it was Category 2 and before you know it, it was Category 4", O Shaughnessy said. "We haven t seen as robust of an evacuation response from the civilian population that we have seen in other storms".
Only three major hurricanes made landfall in the Panhandle since 1950 before this: Eloise in 1975, Opal in 1995 and Dennis in 2005. Tropical storm conditions are expected in the warning area along the southeast USA coast by Wednesday, and possible in the watch area by late Wednesday.
NHC's Graham warned that the storm would continue to pack tropical storm-force winds when it reached the Carolinas, still reeling from severe flooding in the aftermath of Hurricane Florence last month. Reports from an Air Force Reserve Hurricane Hunter aircraft indicate that maximum sustained winds have increased to near 140 miles per hour (225 kph) with higher gusts. Coastal counties began issuing evacuation orders and opening emergency shelters at schools on Sunday, as member station WFSU reports.
The National Hurricane Center says Michael is expected to move off the mid-Atlantic coast and head back out to sea on Friday. "This happened so quickly", he said.
Trump issued an emergency declaration for Florida, freeing up federal funds for relief operations and providing the assistance of FEMA, which has more than 3,000 people on the ground.
University of Georgia's Marshall Shepherd, a former president of the American Meteorological Society, called it a "life-altering event" on Facebook and said he watched the storm's growth on satellite images with a pit growing in his stomach.
In terms of wind intensity, that would make it stronger than Hurricane Florence, which had winds of 90 miles per hour when it blew ashore in North Carolina last month. He chose the spot where his house stands on tall stilts overlooking the Gulf waters in 1972 after it was the only lot left dry after a storm flooded the beach that year.