(CNN) -- Tropical Storm Alberto, the first named storm of the 2012 Atlantic hurricane season, formed Saturday off the coast of South Carolina.
As of 5 p.m., the storm was located about 140 miles east-southeast of Charleston, South Carolina, with maximum sustained winds of 45 miles per hour, the Miami-based National Hurricane Center said.
It was churning southwest at 3 mph.
No coastal watches or warning were in effect, though a tropical storm watch could be issued for parts of the coast later Saturday, the Hurricane Center said.
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Despite being over the warm waters of the Gulf Stream, Alberto is not expected to intensify much over the next couple of days. That is due, in part, to the presence of a cool and dry air mass to the north and west of the tropical storm, said CNN meteorologist Sean Morris.
The forecast track shows Alberto moving slowly toward the south-southwest over the next day or so and then accelerating rapidly toward the northeast, away from the U.S. coast on Monday.
This year marks the first time in recorded history that a tropical storm has formed in both the east Pacific basin and Atlantic basin before the official start of hurricane season, the Hurricane Center said. The Pacific storm was called Aletta.
The Atlantic hurricane season officially begins on June 1.