Forecasters at the U.S. National Hurricane Center have downgraded Alberto from a tropical storm to a depression.
As of 5 a.m. Eastern time (0900 GMT), Alberto was located about 60 kilometers southwest of the town of Columbia, South Carolina, with maximum sustained winds of 55 kilometers per hour.
A tropical depression is a tropical cyclone with maximum winds up to 61 kilometers an hour.
Forecasters say Alberto could dump several centimeters of rain on parts of North and South Carolina, as well as Virginia, and isolated tornadoes are possible in the Carolinas Wednesday.
Alberto has weakened ever since it made landfall Tuesday afternoon on Florida's gulf coast. The storm dumped several centimeters of rain across the state, triggering flooding and extinguishing wildfires that had been burning for several weeks in drought-stricken areas.
Emergency officials say no serious injuries or deaths have been reported. The storm left thousands of households without power for several hours.
Alberto is the first named storm of this year's Atlantic hurricane season, which began June 1.
Some information for this report was provided by AFP, AP and Reuters.