The first named tropical system has formed in the Gulf of Mexico just off the Florida coast.
The National Hurricane Center says an air force reconnaissance plane was able to identify a well-defined circulation.
A tropical storm warning is in effect from Boca Grande to the Ochlockonee River on Florida's west coast. A tropical storm watch is in effect from Flagler Beach to Surf City, North Carolina.
A flood watch is in effect for the entire area until Friday afternoon.
Andrea is expected to move across the state Thursday bringing heavy rains possibly four to six inches in some areas to the First Coast and much of Florida. The National Weather Service in Jacksonville says minor flooding is likely but the storm will move quickly and head up the Atlantic Coast by Friday.