MIAMI (AP) -- Forecasters have issued tropical storm warnings for the Southeast coast from northeastern Florida to South Carolina as a cluster of thunderstorms is gathering strength and expected to become Tropical Storm Beryl over the Memorial Day weekend.

The National Weather Service said Friday night that the storm's winds were at 45 mph. But they are expected to increase as the storm slows down in the Atlantic.

The system was about 305 miles (490 kilometers) from Charleston, S.C., and swirling toward the Southeast coast.

Tropical storm warnings are out for the Volusia/Brevard County line in Florida to Edisto Beach, S.C. The storm is expected to eventually move southwest and the Georgia coast could see heavy rains.

Higher than normal tides will be crashing against the Southeastern coast and may cause flooding. Heavy rain is forecast.