Found in Cullman, hailstone measured a whopping 20 cubic inches

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Susan G. Millerick
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TAMPA, March 27, 2018 – The Insurance Institute for Business & Home Safety (IBHS) is proud to announce the documentation of what our staff meteorologists believe is the largest hail stone ever to have fallen in Alabama, and one of the three largest ever documented east of the Mississippi river.

At 5 3/8 inches (13.665 cm) at its largest measurement and approximately 0.6125 or 5/8 of a pound. Its total volume was approximately 20 cubic inches. For comparison, a tennis ball is about 9.6 cubic inches and a baseball is about 13.4 cubic inches, and a soda can is about 25 cubic inches.

The hail stone is estimated to have hit the ground – and fortunately not a person, vehicle or roof – at approximately 88 mph, with an impact energy of 1890 joules. For reference, a typical 2-inch hailstone falls at about 65 mph with an energy of 24 joules. This hail stone left a divot in the ground that was approximately 6 inches in diameter and 3 inches deep. The entire storm inflicted serious damage to vehicles and homes in the area.

The hail stone fell during a severe storm on March 19 in Cullman, Alabama and was retrieved by Craig Mann from his front yard. Mann shared his finding with the National Weather Service (NWS) which visited Cullman to verify the hail stone’s measurements, along with other stones retrieved by Mann during the same event, several of which also measured extraordinarily large at between 3.6 and 4.5 inches.

For enhanced documentation, IBHS was contacted to further measure the size, density, weight, volume, impact and other details using its proprietary 3-D scanning equipment. IBHS has established a leading expertise in hailstone analysis as part of an ongoing effort to better understand and provide documentation for hail damage, and, in collaboration with the NWS, to improve hail forecasting.

Hail, which causes billions of dollars in property damage annually is of growing interest among meteorologists, risk modelers and property insurers as well as roofing material manufacturers, all of which aim, through further study and improved forecasting, to reduce the damage hail inflicts on homeowners and their property.

“Hail has largely been passed over for study funding because greater interest has driven enhanced science in the understanding of hurricanes, tornadoes and other severe weather events,” said Ian Giammanco, Ph.D., Lead Research Meteorologist. “But Hail’s day has come and IBHS is working along multiple paths to improve our ability to build with materials that can withstand hail, and to improve forecasting of hail so people can protect vehicles, and other possessions that might be outdoors.”

During 2017, according to the National Oceanic and Atmospheric Administration (NOAA), there were 6,045 hail storms in the United States, including six events that each caused more than $1 billion in property damage. The most costly impacts in 2017 were in the Denver metro region, where baseball-sized hail caused the most expensive hail storm in Colorado history, with insured losses exceeding 2.2 billion.

The largest hailstone ever documented in the United States fell in Vivian, South Dakota in June 2010. “Vivian” as the stone is called, was 56.6 cubic inches.

Photos of the hailstones, the documentation, and damages are available here.

Learn more about IBHS’ hail study at https://disastersafety.org/hail/ibhs-hail-field-studies/

IBHS thanks Craig Mann for making this contribution to the science of hail.

IBHS Hail Field Study - Cullman, AL Record Hailstone


About the Insurance Institute for Business & Home Safety (IBHS) IBHS’ mission is to conduct objective, scientific research to identify and promote effective actions that strengthen homes, businesses, and communities against natural disasters and other causes of loss.