THE NATIONAL WEATHER SERVICE IN STERLING VIRGINIA HAS ISSUED A * SEVERE THUNDERSTORM WARNING FOR... WASHINGTON COUNTY IN NORTH CENTRAL MARYLAND... FREDERICK COUNTY IN NORTH CENTRAL MARYLAND... MONTGOMERY COUNTY IN CENTRAL MARYLAND... FAUQUIER COUNTY IN NORTHERN VIRGINIA... LOUDOUN COUNTY IN NORTHERN VIRGINIA... JEFFERSON COUNTY IN THE PANHANDLE OF WEST VIRGINIA... PRINCE WILLIAM COUNTY IN NORTHERN VIRGINIA... * UNTIL 900 PM EDT * AT 817 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM CAPABLE OF PRODUCING HAIL UP TO THE SIZE OF QUARTERS AND DAMAGING WINDS IN EXCESS OF 60 MPH. THIS STORM WAS LOCATED NEAR ST. LOUIS...AND MOVING NORTH AT 60 MPH. * LOCATIONS IMPACTED INCLUDE... PURCELLVILLE... ROUND HILL... NEERSVILLE... BRUNSWICK... POINT OF ROCKS... BRADDOCK HEIGHTS... BALLENGER CREEK... FREDERICK... PRECAUTIONARY/PREPAREDNESS ACTIONS... A TORNADO WATCH IS IN EFFECT FOR THE WARNED AREA. THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH...PREPARE IMMEDIATELY FOR DAMAGING WIND GUSTS...LARGE HAIL AND FREQUENT CLOUD TO GROUND LIGHTNING. MOVE INDOORS TO A STURDY BUILDING AND STAY AWAY FROM WINDOWS.