Unsettled weather is forecast to continue through the first half of the work week from the Southern Plains to the Great Lakes as a frontal system moves through. Isolated to scattered severe thunderstorms and flash flooding will be possible each day. Meanwhile, scattered showers and thunderstorms are expected across the Southwest and California, with isolated flash flooding possible. Read More >
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.
Above information borrowed and edited from FEMA publication:
https://www.fema.gov/hazard/thunderstorm/index.shtm