Calgary's "Hail Alley" provides valuable data for hailstorm research

Calgary Herald

14-07-2025

If there's two things that are guaranteed for the summer in Calgary, it's always Stampede and the seasonal hailstorms that hit the city right after. Following a flash hailstorm on Sunday, climate experts explain why they always take place around this time of year.
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Due to Alberta's geography, scientist with Environment and Climate Change Canada Christy Climenhaga, said it gives the province with the most optimal conditions for our 'Hail Alley.'
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'It kind of runs from Drayton Valley, south towards the south side of Calgary towards that main hail corridor, especially if you are located on the northern side of the city,' she said.
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Historically, Calgary experiences intense hail events every few years.
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With the last few major events taking place in August of 2024 and 2022, Climenhaga said it is generally around this time of year when the dynamics of the weather play a role in creating intense storms.
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'You need very strong updrafts inside of a thunderstorm, often a supercell thunderstorm will produce these larger hail stones,' Climenhaga said. 'You need enough moisture, a freezing level where that moisture has to be lifted, where those ice stones can form to really all line up to get big hailstorms.
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'Calgary often does have that perfect setup, where you do have low enough freezing levels where you do get that moisture pushed up enough to really grow those hailstones.'
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Simon Eng, research meteorologist for the Northern Hail Project run out of Western University in Ontario, said they've received reports of Sunday's storm hosted hailstones that ranged from 40 to 45 millimetres in size, alongside gusts of wind in the 90 km/h range.
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'You had a lesser magnitude hail event yesterday, but other factors present that may have turned up the dial and increased the risk of some of these attendant hazards that are associated with severe thunderstorms,' Eng said.
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There are three overall programs that the NHP uses to collect data over the summer.
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First are teams based in Olds and Olds College throughout the summer, generally tasked with chasing storms wherever they occur around the province.
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Second is their instrumented networks branch that use specialized weather stations and equipment for hail monitoring across Calgary and surrounding agricultural areas.