Tropical Storm Alberto, the first of the Atlantic hurricane season, formed off the coast of South Carolina on Saturday.

As of 11 p.m. Saturday, Alberto was about 110 miles southeast of Charleston, S.C. It had maximum sustained winds of 50 mph with higher gusts and was moving southwest at 6 mph.

The storm is expected to continue moving southwest through Sunday before turning toward the west-northwest and then toward the north and northeast on Monday.

A tropical storm watch was issued for the coast of South Carolina from the Savannah River to the South Santee River.

The official start to hurricane season is June 1, but tropical storms sometimes occur before then.