Hurricane Michael grew into a major Category 3 storm as it howled closer to Florida's Gulf shore on Tuesday, sending tens of thousands of coastal residents fleeing to higher ground one day before its expected arrival with towering waves and roof-shredding winds.
Michael is projected to plow into Florida's panhandle at midday on Wednesday, unleashing potentially devastating waves of seawater as high as 12 feet (3.6 meters) that could rush inland for miles around the storm's center, the National Hurricane Center (NHC) warned.
By Tuesday, Michael was already causing major disruptions to U.S. oil and gas production as it churned north over the Gulf of Mexico.
President Donald Trump declared a state of emergency for the entire state of Florida, freeing up federal assistance to supplement state and local disaster response.
At latest report, the NHC said the storm was packing sustained winds of up to 120 miles per hour (195 km per hour), jumping from a Category 2 to Category 3 hurricane on the five-step Saffir-Simpson wind scale.
Winds of that magnitude can inflict substantial damage to roofs and walls of even well-constructed homes, according to the National Weather Service.
The storm also is likely to dump prodigious amounts of rain over Florida, Alabama, Georgia and the Carolinas - still recovering from severe flooding last month in the aftermath of Hurricane Florence. Up to a foot of rainfall (30 cm) is forecast for some areas.