Hurricane Michael

PANAMA CITY BEACH, Fla. — Hurricane Michael approached a fortified Florida Panhandle early Wednesday as a Category 4 storm and was expected to make landfall later in the day as the most powerful tropical cyclone to strike the mainland United States this year.

The National Hurricane Center said that the storm had maximum sustained winds of 130 miles per hour. Emergency declarations were issued for parts of Alabama, Florida and Georgia, and the authorities ordered tens of thousands of people to evacuate as they opened storm shelters and shut down schools.

“Hurricane Michael is a monstrous storm, and the forecast keeps getting more dangerous,” Gov. Rick Scott of Florida said during an appearance on Tuesday at the state’s emergency operations center in Tallahassee, the state capital.