Okanagan avalanches rare but deadly
Any steep snow-covered slope can prove deadly, even in the Okanagan Valley. As history proves, Okanagan avalanches are rare but they have been deadly.
“Avalanches can occur in the Okanagan and there is currently a considerable risk of avalanche danger in the Okanagan Valley,” says Ross Goddard, Avalanche Canada forecaster. “This means dangerous avalanche conditions exist. Careful snowpack evaluation, cautious route-finding and conservative decision-making are essential.”
A persistent weak layer of surface hoar is buried 50 to 70 centimetres down, he explained. “This depth is prime for human triggering on all slope aspects and all elevations (alpine, treeline, below treeline). Below treeline, this layer may present (appear) as a rain crust. Deeper in the snowpack, near the ground, the snowpack is very weak and can be triggered under the right circumstances.”
With warming temperatures, wet loose avalanches may also be a problem on south-facing slopes, said Goddard.
“Wet loose avalanches in motion have the potential to trigger weak layers deeper in the snowpack to create larger, more destructive avalanches. Signs of instability like pinwheeling and tree bombs will clue backcountry users into surface layers becoming unstable as temperatures rise. The first sign of instability at one of our deeply-buried weak layers could be a large, destructive avalanche. Choose terrain that won’t expose you to the consequences.”
Backcountry users should be mindful that instabilities deep in the snowpack are still present and have produced recent large avalanches, he added. “Avoid thin areas like rock outcroppings where you’re most likely to trigger avalanches failing on deep weak layers. Reduce the consequences by sticking to low-angle terrain and smaller pieces of terrain that aren’t capable of producing large avalanches. Avoid slopes with terrain traps such as cliffs and deep depressions where even a small avalanche can have deadly consequences.”
In general, slopes less than 30 degrees are considered low-angle. There are quite a few mobile apps that can determine slope angle and some backcountry users will even travel with a clinometer to measure the incline.
Seven avalanches in the valley reported since 2008
• Last Monday, one person was taken to hospital after being caught in an avalanche near Cherryville. Emergency Health Services (BCEHS) confirms that paramedics received a call at 2:15 p.m. Monday and dispatched an ambulance to the Cherryville area, before transporting one patient to hospital. BCEHS did not disclose the extent of the person’s injuries.
• On April 18, 2021, Big White Ski Resort was closed for the season when a size two avalanche cascaded down an area called the Cliff. According to Avalanche Canada, size two avalanches can bury, injure or even kill a person.
“That’s a big avalanche – you don’t mess around with that. It’s dangerous. When we closed the resort, we stopped throwing hand-bombs. There’s no more blasting to take place to make the area safe where people can ski and snowboard.
We stopped doing them the day we closed,” said Michael J. Ballingall, senior vice president of Big White Ski Resort, afterward.
According to Avalanche Canada’s website at the time: “The best and safest riding will be high north-facing terrain that is free from cornices overhead. Expect avalanche activity on sun-exposed slopes.”
• On Jan. 6, 2008, a 42-year-old experienced snowboarder with a season pass was killed in an in-bound double-blackdiamond area called the Parachute Bowl at Big White Ski Resort. Two snowboarders were partially buried but survived and taken to hospital. The avalanche area stretched across two acres at the bottom but was less than one metre deep.
When he was reported missing, teams searched the backcountry outside the resort boundary, and found the snowpack unstable with a considerable avalanche risk.
• At noon on March 20, 2019, Nathan Fisher, a passionate snowboarder and longtime Vernon snowboard shop employee, was critically injured on a double-black-diamond run in the Putnam Creek or steep backside of Silver Star Mountain Resort. Then a second avalanche occurred on the front side near the gondola. No one was hurt in that slide.
The resort said warming temperatures played a role in causing an isothermal avalanche which occurs when all layers of the snowpack are at the same temperature, typically at the freezing point.
Fisher was snowboarding with a friend on a run that requires hiking to access. The avalanche let loose behind him, caught him and dragged him through trees causing broken bones, broken ribs and a collapsed lung.
• On Jan. 6, 2022, the first of two avalanches on the slopes of Apex Mountain caught three of eight skiers, burying two of them and catching the third, leaving a debris pile two metres deep. It was triggered while skiers were cutting below the ski line.
The second avalanche caught a skier who deployed an air bag and was found partially buried.
• On Feb. 8, 2020, several avalanches were triggered on the same peak, Apex Mountain. It is not part of the resort which is on the slopes of Mount Beaconsfield, but two ridges over. No one was injured. One slide was caused by a snowmobiler, and another was triggered by experienced backcountry skiers who were doing ski-cutting, cutting across the top of the terrain, to test the stability. The area received 150 cm of fresh powder during the past six days.
• On Feb. 9, 2020, Summerland snowmobiler Sam Johnson was partially buried in an avalanche in the Powder 8 area southwest of Penticton near Apex Mountain. A group of snowmobilers was descending into a gully between two mountains when several slides came down, including one behind Johnson and another in front of him.
He deployed an inflatable airbag he wears as a backpack and tried to sled away but the rushing snow swept his sled out from under him as he jumped toward a tree. His lower body was buried but the airbag kept his shoulders above the snow.
The Avalanche Canada website received reports of multiple backcountry avalanches witnessed in the general area of Apex Mountain, including the slides that Johnson was swept up in.
Apex Mountain Resort was blasting with dynamite in the mornings after heavy snowfalls and the province had also done blasting with a helicopter to ensure a slide didn’t release onto a road. About 150 cm of snow fell in six days.
About the same time, a backcountry avalanche was triggered by an experienced rider who went out-of-bounds at the resort.
In that case, the person was testing the snowpack to see if it was stable when the slide was triggered. No one was caught.