On a given day there are 1,800 thunderstorms around the globe.That's 16 million a year. The U.S. alone sees about 100,000 every year and only ten percent of those are actually classified as severe. So what really makes a thunderstorm a severe thunderstorm?

The national weather service classifies a severe thunderstorm as a storm with hail at least 1 inch in diameter or larger... and/or wind gusts greater than 58 miles per hour.

Warnings are issued by meteorologist at the national weather service, like the one here in Chanhassen, when these criteria are seen on radar or reported by trained spotters.

These criteria were set forth because at these strengths loss of property and life are possible.
That's the big takeaway. Hail that large, or wind that fast, generates enough force to take a life, and that's we take it so seriously when we interrupt our programming.

Along with the fatal risk, hail causes more than a billion dollars in property and crop damage yearly. The largest hail stone ever recorded in the US occurred in 2010 near Vivian, South Dakota, came in at 8 inches in diameter and weighing close to 2 lbs.
Wind in these storms can reach upwards of 100 MPH. Uprooting trees, lifting roofs off homes, and even flip trailers. Last year alone strong winds caused 50 deaths.

Remember when you hear severe thunderstorm warning think immediate danger and seek shelter. We're not interrupting the season finale of your favorite show for nothing.

For Weather Whys I'm Meteorologist Joshua Eckl, KEYC News 12.