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Definitions
thunderstorm n. a transient storm of lightning and thunder, usually with rain and gusty winds, sometimes with hail or snow, produced by cumulonimbus clouds. Also called electrical storm.
-Webster's New Universal Unabridged Dictionary, 1994
severe thunderstorm a thunderstorm which produces hail at least ¾-inch in diameter, wind 58 mph or higher, or tornadoes.
-National Weather Service
Introduction
Thunderstorms affect relatively small areas when compared with hurricanes and winter storms. The typical thunderstorm is 15 miles in diameter and lasts an average of 30 minutes. Nearly 1,800 thunderstorms are occurring at any moment around the world. That's 16 million a year!
Despite their small size, all thunderstorms are dangerous. Every thunderstorm produces lightning, which kills more people each year than tornadoes. Heavy rain from thunderstorms can lead to flash flooding. Strong winds, hail, and tornadoes are also dangers associated with some thunderstorms.
Of the estimated 100,000 thunderstorms that occur each year in the United States, only about 10 percent are classified as severe.
Definitions and Introduction | Survival Tips
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