The National Weather Service in Sterling Virginia has issued a * Severe Thunderstorm Warning for... Northwestern Howard County in central Maryland... Montgomery County in central Maryland... Southeastern Frederick County in north central Maryland... Northeastern Loudoun County in northern Virginia... * Until 330 PM EDT. * At 256 PM EDT, severe thunderstorms were located along a line extending from near Ballenger Creek to near Lansdowne, moving east at 50 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... Germantown, Rockville, Bethesda, Gaithersburg, Leesburg, Olney, Damascus, Lansdowne, Poolesville, Aspen Hill, Potomac, North Bethesda, Montgomery Village, North Potomac, Ballenger Creek, Redland, Chevy Chase, North Kensington, South Kensington and North Chevy Chase. PRECAUTIONARY/PREPAREDNESS ACTIONS... Remain alert for a possible tornado! Tornadoes can develop quickly from severe thunderstorms. If you spot a tornado go at once into the basement or small central room in a sturdy structure. For your protection move to an interior room on the lowest floor of a building. Large hail and damaging winds and continuous cloud to ground lightning is occurring with these storms. Move indoors immediately. Lightning is one of nature`s leading killers. Remember, if you can hear thunder, you are close enough to be struck by lightning. By The National Weather Service.