As we get deeper into spring, you'll be hearing the terms "severe thunderstorm watch" and "severe thunderstorm warning" more often.

"Severe" does have a formal definition. To qualify, a thunderstorm must produce winds in excess of 57 mph - that's 50 knots. Or produce hail that's at least of an inch across - that's about the size of a penny. Or produce a tornado.

The Storm Prediction Center in Norman Oklahoma issues Severe Thunderstorm watches. A watch typically covers tens of thousands of square miles, and means that severe thunderstorms are possible in the next few hours. A warning means that a severe thunderstorm is in progress, is imminent, or has been indicated on Doppler radar. Severe Thunderstorm Warnings are issued for individuals counties or parts of counties by the local National Weather Service office - ours is in Mount Holly, NJ.

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