He advised tourists and residents that had yet to heed evacuation calls early Wednesday to "hunker down", warning, "It's going to get worse pretty fast here".
Hurricane Michael weakened to a Category 1 storm late Wednesday as it moved across south-central Georgia with maximum sustained winds of 75 miles per hour.
It's the worst storm to hit the Florida panhandle in over a century.
Many homes were ripped apart or washed away altogether in Mexico Beach, a town of 1,000 where the hurricane made landfall and the storm surge pushed lead-grey water up to the rooftops. Video footage captured during the storm showed homes totally inundated by storm surge as winds tore houses apart.
The NHC said: "On the forecast track, the center of Michael will move through eastern Georgia into central SC this morning, then moves across portions of central and eastern North Carolina and southeastern Virginia into the Atlantic Ocean by late tonight or early Friday".
Michael, located about 20 miles (30 kilometers) southwest of Albany, Georgia and packing maximum sustained winds of 90 miles per hour (150 km/h), is forecast to become post-tropical cyclone on Friday, the Miami-based weather forecaster said.
The dire verdict is due in part to the extremely rapid strengthening of the storm, from Category 2 in the morning.
"I wanted to let you guys know exactly what is going on", she said, speaking about a curfew that had been instituted in nearby Bay County because of concerns about looting from the outages.
Hurricane Michael earlier made landfall just northwest of Mexico Beach, Florida.
The fate of about 280 residents who authorities said ignored evacuation orders was unknown.
It's time to start praying for Florida.
Hurricane Michael also stands out because of its late arrival.
"This situation has NEVER happened before", it said on Twitter.
Never in recorded weather history has a hurricane hit the mainland United States at such a speed in October, the month marking the end of the June to November hurricane season.
With more than 375,000 people up and down the Gulf Coast warned to evacuate, the hurricane lashed the white-sand shoreline with tropical storm-force winds, rain and rising seas before daybreak, hours before the center came ashore.
President Donald Trump declared a state of emergency for all of Florida on Wednesday. That sort of timetable can make evacuations more hard to manage.
After there, the storm will move up through the Carolinas, hit by heavy rains form Hurricane Florence just a few weeks ago.
Characterized by strong winds and heavy rainfall, the hurricane of 1930 caused severe damage to the Dominican Republic.