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Thunderstorms create downdrafts that can cause the storm to die out or intensify.
In air mass thunderstorms, downdrafts eventually destroy the storm. They undergo a sequence from the cumulus to the mature to the dissipative stages in tens of minutes. Such storms occur within squall lines, in multi- cellular mesoscale convective complexes, or as supercells. Tornadoes, among the most fearsome of all natural phenomena, occur more often in the United States than in any other country of the world-and nearly all the states and Canadian provinces experience them sooner or later.