"Showers and thunderstorms located over the Florida peninsula, the southeastern U.S. coast, the northwestern Bahamas, and the adjacent Atlantic and Gulf waters are associated with a broad trough of low pressure," the National Hurricane Center said.

If the storm becomes tropical later this week, it will be the first tropical storm of the Atlantic hurricane season.

The chance of tropical or subtropical development is low, but localized heavy rain is still expected from Florida to the coastal Carolinas.