A tornado appears as a rotating, funnel-shaped cloud that extends from a thunderstorm to the ground with whirling winds that can reach 300 miles per hour. Damage paths can be in excess of one mile wide and 50 miles long. Some tornadoes are clearly visible, while rain or nearby low-hanging clouds obscure others. Occasionally, tornadoes develop so rapidly that little, if any, advance warning is possible. Before a tornado hits, the wind may die down and the air may become very still. However, some tornadoes can have winds of 200 mph or more. A cloud of debris can mark the location of a tornado even if a funnel is not visible. Tornadoes generally occur near the trailing edge of a thunderstorm.
Maryland usually receives at lease several tornadoes a year. Many hit in sparsely populated rural areas and cause little or damage or casualties. In Maryland, notable tornadoes have caused casualties and/or significant damage in LaPlata and the College Park-Beltsville-Calverton area. The most common time of year for tornadoes to occur in Maryland is April through November, and most occur between 3 p.m. and 9 p.m.