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Posted at 10:00 AM ET, 08/ 2/2010

Hailaceous: South Dakota hailstone breaks record

By Jason Samenow

* Increasing heat & humidity with chance of t'storms: Full Forecast *

Photograph of the hailstone that fell in Vivian, South Dakota July 23, 2010 - the largest on record in the U.S. Photo courtesy National Weather Service.

From the National Weather Service in Aberdeen, South Dakota:

During the late afternoon and early evening hours of 23 July 2010, thunderstorms developed over portions of central South Dakota. Several storms quickly became severe in an environment favorable for supercell thunderstorms. In particular, one very strong supercell thunderstorm moved southeastward across portions of Stanley, Jones, and Lyman counties. One of the hardest hit locations was the community of Vivian, South Dakota, where extremely large hail, destructive winds to 80 mph, and a brief tornado were reported.
A record setting hailstone was ultimately discovered in Vivian, measuring 8.0 inches in diameter, 18.625 inches in circumference, and weighing in at an amazing 1.9375 pounds!! This hailstone broke the previous United States hail size record for diameter (7.0 inches - 22 June 2003 in Aurora, NE) and weight (1.67 pounds - 3 September 1970 in Coffeyvile, KS). The Aurora, Nebraska hailstone will retain the record for circumference (18.75 inches).
The hailstone's official record dimensions were as of the time personnel from the NWS in Aberdeen first observed and measured it. The stone did shrink considerably (melting and sublimation) between impact and when it was first measured by NWS personnel due in part to a power outgage at the residence of the individual who found the stone. It should also be noted that many other stones with diameters exceeding 6 inches were also noted during the storm survey!

Read the full storm report at the National Weather Service, Aberdeen website.

By Jason Samenow  | August 2, 2010; 10:00 AM ET
Categories:  Thunderstorms, U.S. Weather  
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That is so amazing. SO HUGE!

Posted by: Camden-CapitalWeatherGang | August 2, 2010 11:19 AM | Report abuse

What are those black flecks in it? They didn't just get there when the thing hit the ground, they attached way up in the clouds.

Posted by: blasmaic | August 2, 2010 11:50 AM | Report abuse

I was in this storm on vacation with the family. It was one of the scariest that I've ever been in.
Here are my picts of it:

Posted by: bentoenail | August 2, 2010 11:52 AM | Report abuse

Relatives of mine got caught up in this:!/photo.php?pid=31017922&id=1170150297&ref=album&fbid=1367503385534

No injuries. They huddled under a tree and held a backpack over their heads and that was just barely enough to escape unscathed.

Posted by: maralenenok | August 2, 2010 1:14 PM | Report abuse

This record seems to have literally bounced around the Great Plains over the years.

It was held for many years by Potter, NE, then successively by Coffeyville, KS, Aurora, NE, and now Vivian, SD. I'm wondering whether other locations worldwide also have recorded hailstone records for comparison.

One place to check on would be sub-Himalayan North India, parts of Pakistan and Bangladesh. This area has the deadliest hailstorms and is second to the Great Plains in tornado occurrence worldwide. One reason for the deadliness of the hailstorms there relates to the fact that population density is high in many areas, the folks are poor and housing is rather flimsy. The northern Indian subcontinent is aalso in the shadow of a large mountain range, the Himalayas, creating conditions similar to those in the Great Plains.

Posted by: Bombo47jea | August 2, 2010 1:58 PM | Report abuse

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