A severe thunderstorm produces frequent lightning, locally damaging wind (usually with gusts of about 50 miles per hour or more), or hail that is greater than three-quarters of an inch in diameter. Any thunderstorm that produces a tornado is also thought of as severe.
All severe thunderstorms are extremely dangerous and capable of causing death, injury and property damage. Severe thunderstorms are designated by the National Weather Service, based on radar images and damage reports. The state of the atmosphere before storms form may also aid in designating storms as severe, once they do materialize. Severe Thunderstorm Warnings are issued by the NWS and reported promptly on Channel 6 and 6abc.com.