As of 5:00 pm Eastern time (2100 GMT), Michael was about 295 miles (470 kilometers) south of Panama City and moving north at 12 miles per hour (19 kph).
The National Hurricane Center (NHC) said the storm was expected to make landfall on Wednesday afternoon, bringing hurricane force winds, a "life-threatening storm surge" and heavy rainfall. Parts of Florida's curvy Big Bend could see up to 12 feet (3.7 meters) of storm surge, while Michael also could dump up to a foot (30 centimeters) of rain over some Panhandle communities as it moves inland, forecasters said.
Besides the risky storm surge, residents should also prepare for torrential rain and major flooding, Scott said, with 4 to 8 inches of rain expected and even 12 inches possible in some areas. Residents also lined up to buy gas and groceries even as evacuations - both voluntary and mandatory - were expected to pick up the pace Tuesday.
"Because of the damage caused by Hurricane Florence, and the fact that there's still some standing water in places, we have to be that much more alert about the damage that Hurricane Matthew could do", Cooper said.
A hurricane watch is in effect for coastal Alabama and a tropical storm watch is in effect for coastal Mississippi.
Florida has had more hurricanes in October than in any other month.
Authorities stressed the danger of the storm surge, when hurricanes push sea water high above their normal levels causing coastal flooding.
Now ranked as a category-1 storm on the five-step Saffir-Simpson wind scale, Michael could grow into a category-3 storm, with the power to uproot trees, block roads and knock out power for days by the time it hits Florida on Wednesday.
Key among these is the pace that hurricane Michael is moving at, meaning it will not drop the massive amounts of rainfall that the Carolina's experienced with Florence. The storm was centered about 390 miles (627 kilometers) south of Apalachicola and 420 miles (675 kilometers) south of Panama City, Florida. Thus, flood is not expected to be a large loss driver with Michael.
If you live in the region Hurricane Michael will be passing through, you can check the latest forecasts and warnings at NOAA's National Hurricane Center. "We're going to get storm surge, we have wind, we have a chance of flooding, we have a significant chance of tornadoes". At present, a maximum of 10 inches of rain is forecast to fall over the Florida panhandle and southern Georgia.
But Maul said some areas had been delayed issuing orders as well as taking other actions to prepare potentially affected regions for the hurricane. But forecasters expect the wind shear buffering the storm to decrease today, allowing it to continue to mushroom in wind speed.
Hurricane Michael in the Caribbean could have also contributed.
Michael was packing sustained winds of up to 85 miles per hour (140 kph) and gaining strength as it skirted past Cuba's western tip en route to a likely Wednesday landfall as the most powerful storm to strike the Florida Panhandle in at least a decade. "Do not think you can survive it", Scott said. "This is the real thing, a significant threat to life and safety". Widespread power outages, wind damage and debris produced by high winds and heavy rain are possible.
In Georgia, Gov. Nathan Deal declared a preemptive state of emergency for 92 counties.
Even political campaigning took a back seat for Tallahassee Mayor Andrew Gillum, Florida's Democratic nominee for governor, who instead helped residents fill sandbags.