Contact: Marcie Katcher 631-244-0149

FOR IMMEDIATE RELEASE August 20, 2009

Large Hailstone Sets Vermont State Record

NOTE TO REPORTERS: High resolution photographs available for download at http://weather.gov/btv/photos. Credit: NOAA

A hailstone that hit Westford, Vt., north of Burlington, during a severe thunderstorm on July 16, 2009, has been declared the largest hailstone ever recovered in the state of Vermont. The hailstone measured 3.3 inches in diameter – roughly the size of a large apple – had a circumference of 6.8 inches and weighed 2.1 ounces.

“Hail from this storm damaged cars and crops, and even injured and killed dozens of chickens,” said Chuck McGill, a National Weather Service meteorologist who collected the record-setting hailstone at his house in the Westford area. "I had never seen hail anywhere near as large as what fell at my house, and I knew hail that size was unusual for Vermont."

The hailstone was officially declared a record by the Vermont State Climate Extremes Committee, comprised of representatives from the National Weather Service forecast office in Burlington, National Weather Service Eastern Region Headquarters, NOAA’s National Climatic Data Center, the Northeast Regional Climate Center and a hail expert from Colorado State University.

Data archived at NOAA’s National Climatic Data Center in Asheville, N.C., indicate only five reports of hail measuring two and a half inches in diameter or larger in Vermont since more comprehensive record keeping began in the early 1950s. The previous largest hailstone reported for the state of Vermont was three inches in diameter and occurred on August 9, 1968, in Burlington.

The largest hailstone on record for the United States fell in Aurora, Neb., on June 22, 2003, and measured seven inches in diameter and 18.75 inches in circumference. The heaviest hailstone fell in Coffeyville, Kan., on September 3, 1970, and weighed 1.65 pounds.

Hail forms when updrafts–upward movement of air–within a thunderstorm carry rain drops into the sub-freezing upper parts of the cloud. As these updrafts cycle the hailstone through the cloud it picks up moisture in the warmer sections of the cloud, which then freezes in the colder sections allowing the stone to grow. Updrafts keep the hailstones aloft until they become too heavy to remain in the clouds. The stronger the updraft, the larger the hailstone can grow before falling to the ground.

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On the Web: National Weather Service, Burlington, Vt.: www.weather.gov/btv