How does hail get so big?

7:17 AM, Aug 8, 2013   |    comments
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GOLDEN VALLEY, Minn. - With all the pictures posted on our Facebook page, it's easy to see just how massive the August 6th storm was. It tracked well over 200 miles, dropping large hail along the way.

The largest hail stone reported was 3 inches, in Kandiyohi County. That's the size of a tea cup!

Here's how hail gets to be so large: It's all about the updraft (a strong vertical wind that travels from the surface to the storm cloud's upper-most levels). For golf ball sized hail and larger, Tuesday night's updraft would have been between 60 and 85 miles per hour.  The stronger the updraft, the larger the hailstones.

Even though the surface temperature was in the 70's and 80's yesterday, upper levels of the atmosphere are below freezing, so instead of raindrops, there are ice crystals. As those ice crystals fall and melt, they get caught in the updraft and are sent right back to the top of the cloud; forming a small hailstone.  This cycle happens several times- each time the hailstone is coated with raindrops, freezes, and gets a bit bigger.

With a strong updraft like Tuesday's, even big hail can be supported within this cycle.  When it gets too heavy for the updraft to support, it falls to the ground.

The Twin Cities' golf balls and tea cups from Tuesday hardly seem less impressive when compare with the largest U.S. hailstone, which was the size of a volleyball. That fell in Vivian south Dakota back in July of 2010.

(Copyright 2013 by KARE. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.)

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