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‘Monday’s storm was remarkable’: Giant hailstones batter cars in Canada

A record-breaking hailstone was recovered after a storm near Markerville, Alberta on Aug. 1. The hailstone had a diameter of 4.8 inches.Francis Lavigne-Theriault / Northern Hail Project

A giant hailstone, tipping the scales at nearly two-thirds of a pound, was recovered in Canada on Monday, setting a new national record, according to officials at Western University in Ontario.

The university’s Northern Hail Project field team located the hailstone — which has a diameter of approximately 4.8 inches — after a severe storm near Markerville, Alberta. It weighed approximately 0.64 pounds and boasted a diameter larger than a softball (3.82 inches) and standard DVD (4.72 inches).

The previous Canadian record holder was a hailstone weighing 290 grams, or approximately 0.63 pounds, that was recovered in Cedoux, Saskatchewan, on July 31, 1973, university officials said in a statement.

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Monday’s storm dropped hailstones that were the size of baseballs, softballs, and grapefruits in Alberta, university officials said. Photos and videos on social media showed how giant hailstones smashed through the windows of vehicles.

One video captured a harrowing scene of people inside a vehicle cowering and covering their heads as huge hailstones pelted the roof of the car, cracked the windshield, and shattered one of the back seat windows.

Julian Brimelow, the executive director of the Northern Hail Project, said finding hailstones of that size “is like hitting the jackpot.” He helps maintain a database of record hailstones, and only 22 of them — including the record-breaking hailstone from Markerville — have weighed more than 290 grams, university officials said.

“By any measure, Monday’s storm was remarkable,” Brimelow said in the statement. “If you were to ask experts where in Canada a new record largest hailstone would be found, they would probably say Saskatchewan. We were expecting significant severe hail in Alberta on Monday, but not a new national record.” Alberta and Saskatchewan are landlocked provinces located next to each other in Western Canada.

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Giant hailstones are rare and researchers are still learning about what conditions are needed for hailstorms to produce them, university officials said.

“Every new data point helps inform us on what conditions are required,” Brimelow said in the statement. “Once we have measured and 3D-scanned the Markerville hailstone, we can then make thin sections. The growth layers evident in those will reveal information on the hailstone’s growth history in the storm.”

The largest hailstone documented in North America fell in South Dakota on July 23, 2010 and weighed nearly two pounds. It had a maximum diameter of 7.9 inches, university officials said.

As the climate warms, scientists say there may be fewer total hailstorms in our future, but more incidents of large or so-called “gargantuan hail,” a class of hail that describes ice balls bigger than 6 inches in diameter.

Scientists expect this because as the ocean warms, the amount of water that evaporates from its surface is increasing, leading to an increase in severe storms.

When those storms become what’s known as a supercell thunderstorm—meaning they have a mesocyclone within the cloud—the powerful updraft allows hailstones to stay in the air longer, and grow larger. With a warmer temperature, studies indicate that more melting happens inside those thunderstorms, but while it’s enough to melt small hail, the larger hailstones are less affected.


Emily Sweeney can be reached at emily.sweeney@globe.com. Follow her on Twitter @emilysweeney and on Instagram @emilysweeney22. Sabrina Shankman can be reached at sabrina.shankman@globe.com. Follow her on Twitter @shankman.