NWS explains how hail forms

MARQUETTE, Mich. (WJMN) – When large chunks of ice fall out of the sky, it can be a little unsettling. Hail is a form of precipitation that occurs sometimes in thunderstorms.

“Hail is just simply the chunks of ice that fall out of a thunderstorm,” said Matt Zika, a meteorologist at the National Weather Service. “And every thunderstorm starts with an updraft. That’s what drives the thunderstorm and that rising air and that thunderstorm and weaker storms maybe going vertically upwards that maybe 10 to 20 miles per hour. But the strongest storms, you may have wind going vertically upward at over 100 miles per hour.”

Hailstones are formed when rain drops get carried upwards in a thunderstorm’s updraft.

As the rain travels upwards it freezes when it reaches a layer of the atmosphere that is below freezing. As the frozen water droplets continue to be swept upwards, they will begin to collide and form additional layers of ice. This creates the hailstone.

Depending on how strong the updraft in the thunderstorm is, the hailstone will continue to be pushed upwards until it is too heavy and it falls.

“Sometimes they get caught back up in the updraft and go for another trip all the way to the top of the storm and continue to get larger and larger,” explains Zika. “And that’s why a lot of times that you see bigger hailstones and you cut them in half. It almost looks like the tree rings where you can count the number of trips, these hailstones that made it all the way through a thunderstorm cloud.”

These chunks of ice can be small and harmless or even large enough to cause damage.

“The national Weather Service uses the definition for severe thunderstorms where if we think a storm is going to have quarter sized hail or larger or wind speeds, wind gusts over 60 miles per hour, typically quarter sized hail or smaller, isn’t going to do significant damage to your cars and roofs, things like that,” said Zika. “Once you start to see hailstones upwards of that golf ball size, two inch diameter or even larger, that’s where you’re going to start to notice dents on your vehicle and and damage to roofs and things like that. So that’s about where the threshold is for more damaging hail as once you surpassed that inch and three quarter type mark.’

If you know there is a storm headed your way that could be producing hail, it is best to bring in your mobile plants, cover your car, and head inside.

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