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1. What is a thunderstorm?

A thunderstorm is a rain shower during which you hear thunder. Since thunder comes from lightning, all thunderstorms have lightning. Why do I sometimes hear meteorologists use the word “convection” when talking about thunderstorms? Usually created by surface heating, convection is upward atmospheric motion that transports whatever is in the air along with it—especially any moisture available in the air. A thunderstorm is the result of convection.

2. What is a severe thunderstorm?

A thunderstorm is classified as “severe” when it contains one or more of the following: hail one inch or greater, winds gusting in excess of 50 knots (57.5 mph), tornado.

3. What is a severe thunderstorm watch?

A severe thunderstorm watch is issued by the NOAA Storm Prediction Center meteorologists who are watching the weather 24/7 across the entire U.S. for weather conditions that are favorable for severe thunderstorms. A watch can cover parts of a state or several states. Watch and prepare for severe weather and stay tuned to NOAA Weather Radio to know when warnings are issued.

4. What is a severe thunderstorm warning?

A severe thunderstorm warning is issued by your local NOAA National Weather Service Forecast Office meteorologists who watch a designated area 24/7 for severe weather that has been reported by spotters or indicated by radar. Warnings mean there is a serious threat to life and property to those in the path of the storm. Act now to find safe shelter! A warning can cover parts of counties or several counties in the path of danger.

5. What kinds of damage can thunderstorms cause?

Many hazardous weather events are associated with thunderstorms. Under the right conditions, rainfall from thunderstorms causes flash flooding, killing more people each year than hurricanes, tornadoes or lightning. Lightning is responsible for many fires around the world each year, and cause fatalities. Hail up to the size of softballs damages cars and windows, and kills wildlife caught out in the open. Strong (up to more than 120 mph) straight-line winds associated with thunderstorms knock down trees, power lines and mobile homes. Tornadoes (with winds up to about 300 mph) can destroy all but the best-built man-made structures.