premise: A thunderstorm produces nothing.
hypothesis: A severe thunderstorm outbreak , also called a severe weather outbreak or simply a severe outbreak , is an event in which a weather system or combination of weather systems produces a multitude of severe thunderstorms in a region over a continuous span of time . A thunderstorm , also known as an electrical storm , lightning storm , or thundershower , is a storm characterized by the presence of lightning and its acoustic effect on the Earth 's atmosphere , known as thunder . Damage that results from thunderstorms is mainly inflicted by downburst winds , large hailstones , and flash flooding caused by heavy precipitation .