Thunderstorm Definition

Thunderstorm - A rain-bearing cloud that also produces lightning.

All thunderstorms are dangerous. Every thunderstorm produces lightning. In the United States, an average of 300 people are injured and 80 people are killed each year by lightning. Although most lightning victims survive, people struck by lightning often report a variety of long-term, debilitating symptoms. Other associated dangers of thunderstorms include tornadoes, strong winds, hail, and flash flooding. Flash flooding is responsible for more fatalities—more than 140 annually—than any other thunderstorm-associated hazard.

Dry thunderstorms that do not produce rain that reaches the ground are most prevalent in the western United States. Falling raindrops evaporate, but lightning can still reach the ground and can start wildfires.

Facts About Thunderstorms

They may occur singly, in clusters, or in lines.
Some of the most dangerous thuderstorms occur when a single thunderstorm affects one location for an extended time.
Thunderstorms typically produce heavy rain for a brief period, anywhere from 30 minutes to an hour.
Warm, humid conditions are highly favorable for thunderstorm development. Usually, thunderstorms

Facts About Lightning

Lightning’s unpredictability increases the risk to individuals and property.
Lightning often strikes outside of the heavy rain in the thunderstorm and may occur as far as 10 miles away from any rainfall.
"Heat lightning" is actually lightning from a thunderstorm too far away for thunder to be heard. However, the storm may be moving in your direction!
Most lightning deaths and injuries occur when people are caught outdoors in the summer months during the afternoon and evening.
Your chances of being struck by lightning are estimated to be 1 in 600,000, but could be reduced even further by following safety precautions.
Lightning strike victims themsleves carry no electrical charge and should be attended to immediately.

Above information borrowed and edited from FEMA publication:
https://www.fema.gov/hazard/thunderstorm/index.shtm