Newly named tropical storm Michael could strengthen to a hurricane as it heads to the Florida Panhandle, the U.S. National Hurricane Center said Sunday.

The Miami-based centre upgraded the tropical depression in the Caribbean to a named tropical storm, saying it had winds of up to 65 km/h.

The storm could strengthen into a hurricane by Tuesday night or Wednesday, the centre said.

It advised residents along the northeastern and central U.S. Gulf Coast to monitor the storm’s progress.

Florida Gov. Rick Scott on Sunday said he planned to declare a state of emergency for counties in the Florida Panhandle and the Big Bend area of the state. The declaration would free up resources for storm preparation.

“As we continue to monitor this storm’s northward path toward Florida, it is critically important that our communities have every available resource to keep everyone safe and prepared,” Scott said in a statement.

The storm was about 145 kilometres south of Cozumel, Mexico, by midday Sunday.

A tropical storm warning was in effect for the Cuban provinces of Pinar del Rio and the Isle of Youth as well as the coast of Mexico from Tulum to Cabo Catoche. A warning indicates tropical storm conditions are expected, in this case, within 24 hours.

An Air Force hurricane hunter airplane was being sent into the storm to investigate, the hurricane centre said.

Michael is the 13th named storm of the 2018 hurricane season, according to hurricane centre spokesperson Dennis Feltgen.