By Jane Sutton
MIAMI (Reuters) - Tropical Storm Alberto formed off the South Carolina coast on Saturday, bringing an early start to the Atlantic hurricane season, forecasters at the U.S. National Hurricane Center said.
Alberto was in the Atlantic about 140 miles east-southeast of Charleston. Forecasters initially estimated its top sustained winds at 45 miles per hour but raised that to 60 mph when data from a ship in the area showed the storm was stronger than first thought.
It was moving slowly southwest and forecasters said a storm watch might be posted later on Saturday for coastal North and South Carolina. Only moderate strengthening was expected.
Alberto was forecast to make a slow loop during the next few days and then turn northeast, making its way along the U.S. mid-Atlantic seaboard before dissipating in about five days.
That would keep it well away from the Gulf of Mexico, where U.S. oil and gas operations are clustered, but could bring squalls and rough surf to the Carolina coast.
The Atlantic hurricane season officially runs from June 1 to November 30, but storms outside that time frame are not uncommon. Alberto was the earliest-forming Atlantic storm since 2003, when Tropical Storm Ana formed more than five weeks before the official start of the season, the hurricane center said.
(Reporting By Jane Sutton; Editing by Peter Cooney)
