The National Weather Service in Sterling Virginia has issued a * Tornado Warning for... East central Frederick County in north central Maryland... * Until 845 PM EDT. * At 811 PM EDT, a severe thunderstorm capable of producing a tornado was located near Discovery-Spring Garden, or east of Frederick, moving northeast at 20 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. * Locations impacted include... Walkersville, Linganore-Bartonsville, Libertytown, Unionville and Mount Pleasant. 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.