As the National Hurricane Center watches system off Florida's coast for potential development, a flood watch has been issued for four counties.

"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.