Subtropical Storm Andrea formed off the southeastern U.S. coast, more than three weeks before the official start of the Atlantic hurricane season, forecasters said.
The year's first named storm had top sustained winds near 45 mph (72 kph) and was centered about 140 miles (220 km) southeast of Savannah, Ga., at 11:00 a.m. New York time, the National Hurricane Center said.
Subtropical systems are hybrid weather formations that are usually weaker than hurricanes and tropical storms. They share characteristics of tropical systems, which get their power from warm ocean waters at their centers, and more typical bad weather that forms when warm and cold fronts collide.