Thunderstorm Thunderstorm Flash Flooding Awareness Thunderstorms are dangerous because they bring the dangers of lightning, high winds, floods, and flash floods, from extremely heavy rainfall. By definition, a thunderstorm is a cloud that contains lightning and thunder. A typical storm is usually 15 miles in diameter lasting an average of 30 minutes.
Every thunderstorm produces lightning, which kills more people each year than tornadoes.
Lightning often strikes outside of heavy rainfall and may occur as far as 10 miles from the rain. If you are outside during a lightning storm, seek inside shelter immediately and stay off the telephone. However, if lightning hits the car you are inside, the steel frame of a hard topped vehicle will provide increased protection provided you are not touching metal when your car is hit by lightning. A down burst is a strong out rush of wind formed by rain cooled air. Strong down bursts which produce extensive damage are often mistaken for tornados.