MINNEAPOLIS (WCCO) —  On Monday afternoon, some Minnesotans saw 4-inch – or softball-sized hail. Hail that large has only happened only 36 times across the state since 1950

So what causes hail to get so big?

“How big hail gets is a function of how strong the storm is,” says Eric Ahasic, a meteorologist with the National Weather Service.

Hail forms when thunderstorm updrafts (the warm, humid air feeding the storm) pull water droplet to the top of the storm. Up there – 60,000 feet in the air — the temperature can be -100 degrees.

“It keeps those particles suspended in the air, and as they stay up there they get bigger and bigger and bigger as more and more of that water freezes on to them,” Ahasic said. “Eventually they get so big, or so heavy, that they fall through the air that’s rising at 50, 70, 100 miles per hour.”

Two-inch hail — or lime-sized hail — can fall 60 to 70 miles per hour. Four-inch hail falls at more than 100 miles an hour. It was that size that busted out several car windows in Delano on Monday.

The largest piece of hail ever recorded was 8 inches – the size of a volleyball. That fell is in South Dakota in 2010.

The National Weather Service prefers people to measure their hail with a ruler, but will take descriptions of coins balls.

“Somebody put it next to a Hot Wheels car or tomatoes in the garden,” Ahasic said. “We don’t know how big those tomatoes are and that gave us a little laugh.”

Heather Brown

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