A storm system heading toward the U.S. is forecast to be a major hurricane as it nears Florida this week.

Tropical Storm Ian is expected to rapidly intensify on Sunday as it goes over warm tropical waters in the Caribbean Sea. It will then strengthen as it tracks north through the Gulf of Mexico, becoming the fifth hurricane of the Atlantic season.

The storm is currently forecast to make landfall on the west coast of Florida or the Florida Panhandle by midday Thursday, potentially strengthening into a Category 4 hurricane as it approaches. Though there is uncertainty about the hurricane's track and intensity.

The National Hurricane Center has advised residents of Cuba, the Florida Keys and the Florida peninsula to have a hurricane plan in place and to closely follow forecast updates.