Thunderstorm. dense clouds, heavy rain or hail, and strong, gusty winds, associated with lightning,

Thunderstorm, a violent, short-lived weather disturbance that is almost always associated with lightning, thunder, dense clouds, heavy rain or hail, and strong, gusty winds. Some thunderstorms can also bring tornadoes and/or hail. ... Thunderstorms are produced by cumulonimbus clouds and form when air rises rapidly.e when layers of warm, moist air rise in a large, swift updraft to cooler regions of the atmosphere. Severe thunderstorms must meet at least one of three different criteria including strong winds winds in excess of 58 mph, hail larger than an inch, or a tornado. Lightning and heavy rain do not make a storm severe, but it doesn't mean they're any less dangerous