Michael was lashing western Cuba on Monday with heavy rains and strong winds.
The speed of the storm - Michael was moving north 12 mph (19 kph) - gave many people a dwindling number of hours to prepare or flee before being caught up in damaging wind and rain.
"It looks like what we are planning for Wednesday is tropical storm-force winds of 39 to 57 miles per hour", said Jonathan Lord, Flagler County's emergency services chief.
Michael is expected to race across the Carolinas late Wednesday and early Thursday, dumping 2 to 5 inches or more of rainfall. "That's the criticality of following directions".
"If you're responsible for a patient, you're responsible for the patient".
People in areas that could be affected should take no chances against such a powerful surge, Scott said, adding, "No one's going to survive", such a wall of water. It's as simple as that.
Still, not everyone is heeding evacuation orders.
The clockwise churn of an area of high pressure centered over DE is what's keeping Michael on a more northerly path toward the Panhandle and away from South Florida, said AccuWeather senior hurricane expert Dan Kottlowski. "And if it gets much worse. we will go".
"Today it is about life and safety", Gillum said.
About 20 miles in from the coast, in Tallahassee, the state capital, people rushed to fill their gas tanks and grab supplies.
Alabama Gov. Kay Ivey issued a state of emergency in anticipation of widespread power outages, wind damage and debris produced by high winds. The governors of Alabama and Georgia also made emergency declarations.
Officially, the National Hurricane Center predicts the hurricane will come ashore with 125mph winds on Wednesday afternoon, but as always with the poorly understood intensification process, there remains some uncertainty. Forecasters said tornadoes could spin off the storm and 7.5cm to 15cm of rain could cause flash floods as it barrels over a corner of the country still recovering from Hurricane Florence.
Michael is expected to sweep up the East Coast, and tropical storm-force winds were projected to reach the state Thursday, according to the center's projections. The storm was centred about 30 miles (48 kilometres) off the western tip of Cuba, and about 520 miles (837 kilometres) south of Apalachicola.
"Up to four to six inches of rain is now expected over the Carolinas, still recovering from the floods caused by Hurricane Florence".
A hurricane Warning was issued from the Alabama-Florida border eastward to Suwannee River. As such, he's declared a state of emergency in three dozen counties while ordering evacuations for 10 counties, including Panama City Beach.
Further explaining, "A fast-moving storm mitigates the possibility of high rainfall totals that would be caused by a slow-moving or stalled storm". Scott is urging people along the Gulf Coast to finish their storm preparations Monday evening.
"Hurricane Michael is forecast to be a Category 3 storm when it makes landfall and the impact could be devastating".
In Gulf County alone, the first to begin ordering residents of low-lying areas to higher ground, mandatory evacuation notices encompassed an estimated 3,800 homes, said Jessica Sasich of the county's emergency operations centre.
The sheriff's office says Wakulla County shelters were rated safe only for hurricanes below that threshold.