Wind and hail that cut across the southern Alberta prairie last month left a “scar” visible from outer space.
On Aug. 20, 2025, 150-kilometre-per-hour gusts shredded crops and stripped grass and ground cover. The storm slashed from south of Calgary to Saskatchewan, affecting about 425,000 acres of insurable crops, plus pasture and native grassland.
That most intense zone of the storm — a sort of epicentre that dragged for hundreds of kilometres — left behind a “hail scar” that can be seen in satellite images published by U.S. space agency NASA.
A patchwork of green shades, representing crops, hay and clumps of trees is replaced by a smear measuring about 15 kilometres wide and 200 kilometres long.
It starts near Vulcan, south of Calgary, and shows the worst damage centred north of Brooks where acreage owners and agricultural producers had home siding demolished down to the nail points. Corn stalks tore in half. Irrigation pivots overturned. Asphalt shingles were sanded bare.
Researchers from the Northern Hail Project at Western University studied the storm’s effects on the ground afterwards. It concluded the heaviest damage, “among the worst the NHP has documented to date,” occurred over 22 kilometres north of Brooks.
“Crop damage in this swath was total, with grain crops levelled and corn left as mostly bare stalks,” it reads. “Even areas of grassland were pulverized, with grass root systems exposed and native shrubs denuded and debarked on their western facing sides.”
Such storms are not uncommon in southern Alberta.
Freelance storm chaser Kyle Britain has listed 12 examples of “hail scars” on his website that have appeared in the province since 2000.
Two weeks later, those who live and work along the most badly hit band are completing cleanup.
Gerald Torkelson farms near Millicent, Alta., and owns a landscape company in Brooks, about 15 kilometres south.
He was one of 100 volunteers from Mennonite church congregations that fanned out to clean up yards and haul debris in the days after the storm. Going from acreage to farm yard, they took away truckloads of leaves and felled trees.
“I’ve seen a lot of hail damage over the years, but I’ve never seen anything like that,” he said, adding that he doesn’t think many of the damaged trees will survive until next spring.
“My yard looks like the moon.”
While they await insurance adjusters, farmers who can work sections a dozen or more kilometres apart still have to harvest crops that avoided the worst damage. What little is left on badly damaged fields will be cut up for livestock feed or plowed under.
For ranchers, the wind pounded grass flat or exposed roots systems on grazing leases of native prairie. That could mean several years of reduced grazing capacity until pasture recovers.
“Everything that was there is gone, so it’s a next-year deal, I guess,” said Brad Osadczuk, who ranches and farms near Jenner, Alta., at the eastern end of the storm’s path.
Many mixed farm producers still have cattle that will go to market this fall.
“This is a large, large storm with lots of claims,” said George Kueber, the provincial adjusting manager with Agriculture Financial Services Corporation’s crop insurance.
“At this time of year when the crops are at mature stage, the losses are devastating … there’s no regrowth or recovery at that point. Everything is mature and what’s lost is lost.”
Northern Hail Project research meteorologist Simon Eng said that crops and vegetation can fill in a hail scar relatively quickly from the perspective of satellite imagery, but it depends when in the growing season the storm hit.
Another “long-track” hail scar in southern Saskatchewan was formed in June 2024. Some regrowth took hold by early July, when the NHP teams visited. By early fall, some crop was ready to be taken off.
That event was less intense than last month’s storm in Alberta, though another equally fierce storm hit south of Brooks on Aug. 4, 2024. One year later, “only the very central high-intensity portion of the hail swath remains visible the next year,” said Eng.
Barry Adams, a retired rangeland agrologist based in Lethbridge, Alta., said localized damage can be felt for years and needs to be managed carefully.
While “prairie is pretty tough,” he said, cattle producers need to assess conditions and manage pasture to encourage regrowth. That means fewer animals or no grazing at all on badly stripped range until cover is re-established.
Adams said wind and hail can scrape off natural mulch that builds up under native grass. That material keeps soil cooler and helps retain moisture in typical 30 C summers with dry wind.
“Ranchers will need to monitor their pastures and recognize those areas needing special management to assist recovery,” he said.
Osadczuk agrees with the assessment, as well as the researcher’s findings that the land’s recovery could take a year or more.
“I’ve got a few neighbours to the north of me that their whole farm looks basically like a parking lot — just dirt. It went from beautiful crops – high-yield crops — to basically dirt in the matter of a half an hour.”
That loss hits hard, he said, especially after a good outlook this summer following years of dry weather.
