Tropical Storm Andrea moved briskly along the South Carolinacoast on Friday, bringing drenching rains and threatening to spawntornadoes as it churns up the Eastern Seaboard, U.S. forecasterssaid.

Andrea, the first named storm of the Atlantic hurricane season,weakened slightly a day after lashing parts of Florida and southernGeorgia with driving rains and high winds.

On Friday, Andrea carried top sustained winds of 45miles per hour and was centered 35 miles north-northeastof Charleston, South Carolina, the National Hurricane Centersaid.

The storm gained speed overnight and was expected to movequickly up the East Coast, said Jack Beven, a hurricane specialistat the Miami-based center.

“It's likely to continue a fast motion towards the Northeastduring the next day or so,” he said.

In South Carolina, authorities said there were no immediatereports of injuries or damage. Scattered power outages werereported in the state, with 2,500 customers losing service.

Tropical storm warnings were in effect for the U.S. AtlanticCoast from South Carolina to Virginia, including the lowerChesapeake Bay, and forecasters warned tropical storm conditionswill continue to spread northward in the area.

Andrea could cause tornadoes in coastal areas from NorthCarolina through Virginia, the hurricane center said.

The storm buffeted Florida's western coast on Thursday, fuelingseveral tornadoes, including one that ripped a roof off arestaurant in the city of Gulfport. After swirling over the Gulf ofMexico, the storm made landfall over the Big Bend area, where theFlorida peninsula joins the mainland.

The Atlantic hurricane season runs from June 1 to Nov. 30.

The U.S. government's top climate agency warned in an annualforecast last month that this year's season could be “extremelyactive” with 13 to 20 tropical storms, seven of 11 of which areexpected to become hurricanes.

Three to six hurricanes could become major at Category 3 orabove, with winds of more than 110 mph (177 kph), the NationalOceanic and Atmospheric Administration said.