There was a storm surge warning in effect from the Okaloosa/Walton county line to the Anclote River in Florida, and a storm surge watch in effect from Ocracoke Inlet, N.C., to Duck, N.C.
The Carolinas aren't expected to get a direct hit from Michael, but even a weakening storm could bring strong winds and inches of rain. The AP reported parts of Florida's lightly populated Big Bend area could see up to 12 feet (3.7 meters) of storm surge.
"We have done everything we can as far as getting the word out", Smith told the Associated Press on Tuesday.
State officials estimate about 375,000 Floridians are under either mandatory or voluntary evacuation orders. "Hopefully more people will leave".
A combination of high tide and storm surge is resulting in elevated water levels across many low-lying areas on the Gulf and Tampa Bay.
"I know people are tired from Florence, but don't let this storm catch you with your guard down", North Carolina Gov. Roy Cooper said, adding, "A number of homes have rooftop tarps that could be damaged or blown away with this wind".
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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.
Large waves were expected from Mexico Beach to Keaton Beach, where they could reach 9 feet to 13 feet in height.
"No one's going to survive" such a wall of water, he said. "But in my experience, it's always blown way out of proportion".
In Escambia County, on the western edge of the Panhandle, evacuations began in Pensacola Beach and other vulnerable areas, but not in Pensacola itself, a city of about 54,000.
Michael could dump up to a foot (30 centimetres) of rain over some Panhandle communities before its remnants go back out to sea by way of the mid-Atlantic states over the next few days. The NHC forecasts up to 8 inches for the panhandle, southeast Alabama, and parts of southwest and central Georgia. And isolated tornadoes were also possible.