The National Weather Service in Sterling Virginia has issued a * Severe Thunderstorm Warning for... Southeastern Washington County in north central Maryland... Southwestern Frederick County in north central Maryland... Northeastern Loudoun County in northern Virginia... * Until 400 PM EDT. * At 320 PM EDT, severe thunderstorms were located along a line extending from Harpers Ferry to 6 miles southeast of Charles Town, moving northeast at 25 mph. HAZARD...60 mph wind gusts. SOURCE...Radar indicated. IMPACT...Damaging winds will cause some trees and large branches to fall. This could injure those outdoors, as well as damage homes and vehicles. Roadways may become blocked by downed trees. Localized power outages are possible. Unsecured light objects may become projectiles. * Locations impacted include... Frederick, Harry Grove Stadium, Ballenger Creek, Brunswick, Braddock Heights, Clover Hill, Point Of Rocks, Adamstown, Jefferson, Lovettsville, Buckeystown, Rosemont, Burkittsville, Hillsboro, Doubs, Clifton, Lucketts, Park Mills, Arnoldtown and Knoxville. PRECAUTIONARY/PREPAREDNESS ACTIONS... For your protection move to an interior room on the lowest floor of a building. By The National Weather Service, Sterling, Va.