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.
Hazards During a Thunderstorm
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% are classified as severe.
Your National Weather Service considers a thunderstorm severe if it produces hail at least 3/4 inches in diameter, wind 58 miles per hour or higher, or tornadoes.
Severe Thunderstorm Watch
Informs you when and where severe thunderstorms are more likely to occur. Watch the sky and stay tuned to know when a warning is issued. Watches are intended to heighten public awareness and should not be confused with warnings.
Severe Thunderstorm Warning
Issued when severe weather has been reported by spotters or indicated by radar. Warnings indicate imminent danger to life and property to those in the path of the storm.