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Friday, August 27, 2010

‘Volleyball’ From the Sky: South Dakota Storm Produces Record Hailstone


Hailstones collected by Vivian resident Les Scott.

Hailstones collected by Vivian resident Les Scott.

High resolution (Credit: NOAA)

On July 23, 2010, a severe thunderstorm struck Vivian, S.D. — a quiet rural community of less than 200. While there was nothing unusual about a violent summer storm, the softball (and larger)-sized hail that accompanied it was extraordinary. In fact, it led to the discovery of the largest hailstone ever recorded in the United States.

Word of Mouth Travels Fast

Once the thunderstorm passed, Vivian resident Les Scott ventured outside to see if there was any damage as a result of the storm. He was surprised to see a tremendous number of large hailstones on the ground, including one about the size of a volleyball. Scott gathered up that stone, along with a few smaller ones, and placed them in his freezer.

Meanwhile, other residents of the small community went outside to check the storm’s aftermath and it didn’t take long for word to get around that Scott had discovered a huge hailstone on his property.

Shortly after the storm NOAA’s Aberdeen, S.D., weather forecast office (WFO) learned that extremely large hail had fallen in Vivian and that a suspected tornado had done some damage south of the town of Reliance. After receiving that information, David Hintz, the warning coordination meteorologist at WFO Aberdeen contacted Lyman County Emergency Manager Steve Manger to coordinate a damage survey.

Record-setting hailstone.

Record-setting hailstone

High resolution (Credit: NOAA)

A Hail of a Stone

The next day, Hintz met up with Manger and they decided to first inspect the hail damage in Vivian before moving onto the tornado damage. Once in Vivian, they heard about the mammoth hailstone in Scott’s possession. After a quick trip to Scott’s home to measure the stone’s circumference and diameter, and send pictures back to the office, it became evident that this was a possible record breaker.

“Mr. Scott told me the area was littered with large hailstones and the largest had a greater diameter when he first found it,” recalls Hintz. “He immediately stored it and several others in his freezer, but a six-hour power outage caused some melting.”

Even after melting, the stone still measured 8.0 inches in diameter and weighed nearly 2 pounds (1 pound, 15 ounces) with a circumference of 18.62 inches.

WFO Aberdeen notified personnel at National Weather Service Central Region headquarters, who, in turn, requested activation of the National Climatic Extremes Committee to examine Scott’s hailstone. Additional personnel from the Aberdeen office traveled to Vivian to measure and weigh the hailstone, and then turned their findings over to the three-person committee.

One for the Record books

Vivian resident displays a roof section that was damaged by the hailstorm.

Vivian resident displays a section of roof that was damaged by the hailstorm.

High resolution (Credit: NOAA)

After a thorough review of the evidence, NCEC — the team responsible for validating national weather records — declared Scott’s hailstone to be the largest in diameter and heaviest ever recovered in the United States.

Scott’s hailstone displaces the previous hailstone record for weight, which was previously 1.67 pounds for a stone in Coffeyville, Kan., that fell in 1970. It also surpasses the record for diameter, which was 7 inches for a hailstone found in Aurora, Neb., in 2003. The Aurora hailstone still holds the record for circumference of 18.75 inches.

Hailstones Pack a Perilous (and Costly) Punch

Hail causes nearly one billion dollars (U.S.) in damage to property and crops annually.

Vehicle dmages by hailstones.

Vehicle damaged by hailstones.

High resolution (Credit: NOAA)

According to NOAA records, hail was the main factor in two weather events since 1980 that caused $1 billion or more in damages to young crops, businesses, homes, cars and trucks. A series of storms over six days in early April 2001 caused $1.9 billion in damages in 13 states, spanning from Texas to Pennsylvania. A three-day event in early April 2003 damaged $1.6 billion in property and agriculture in 10 states stretching from Texas to Tennessee.

Small hail, up to about the size of a pea, can wipe out a field of ripening grain or tear a vegetable garden to shreds. Large hail, the size of a tennis ball or larger, can fall at speeds faster than 100 miles per hour and can batter rooftops, shatter windows and “total” automobiles.

To learn more about hail, visit NOAA’s Hail Basics website.

Information about the National Climatic Extremes Committee and existing weather records may be found online. NOAA logo.