The National Weather Service in Sterling Virginia has issued a * Tornado Warning for... East central Washington County in north central Maryland... Northwestern Frederick County in north central Maryland... * Until 615 PM EDT. * At 528 PM EDT, a severe thunderstorm capable of producing a tornado was located near Shepherdstown, moving northeast at 15 mph. HAZARD...Tornado. SOURCE...Radar indicated rotation. IMPACT...For those in the direct path of a tornado touchdown, flying debris will be dangerous to those caught without shelter. Damage to roofs, siding, and windows may occur. Mobile homes may be damaged or destroyed. Tree damage is likely. * This dangerous storm will be near... Boonsboro, Mount Lena, and San Mar around 535 PM EDT. Other locations impacted by this tornadic thunderstorm include Pleasant Walk, Keedysville, Rohrersville, Myersville, Bolivar, and Sharpsburg. PRECAUTIONARY/PREPAREDNESS ACTIONS... TAKE COVER NOW! Move to a basement or an interior room on the lowest floor of a sturdy building. Avoid windows. If you are outdoors, in a mobile home, or in a vehicle, move to the closest substantial shelter and protect yourself from flying debris. By The National Weather Service, StErling, Va.