Severe thunderstorms are intense weather events characterized by heavy rain, strong winds, hail, and frequent lightning. They can produce damaging winds exceeding 58 miles per hour and may lead to flash flooding. These storms often develop in warm, humid conditions and can form rapidly, sometimes resulting in tornadoes. Meteorologists use specific criteria to classify thunderstorms as severe, including the presence of hail larger than one inch and wind gusts strong enough to cause damage. The National Weather Service issues warnings to alert the public about impending severe thunderstorms, helping people take necessary precautions to stay safe.