Recent snowfall throughout southern B.C. has further complicated an already complex snowpack that formed early this winter and further increased the risk of large avalanches.
“There were some early signs at the start of the season and we have seen the conditions play out as expected,” said Simon Horton, forecaster with Avalanche Canada. “That weak snow that formed during those cold snaps was buried around Christmas and it snowed a lot more in February, so now all those weaknesses are quite deep and producing big avalanches.”
According to Horton there is now a combination of avalanche problems, including the new dump of snow, plus some weak layers that have formed in January that have been especially problematic, particularly around the Kimberley area.
The weak snow around the base has also been a serious issue, particularly north of Kimberley in the northern Purcells, around Revelstoke and in parts of the Rockies.
“Overall the theme is that the snowpack was tricky to start with and now has gotten even more complex and more layered at this time of year,” Horton said.
That deep, weak layer has been a culprit in many of the fatal avalanches that have occurred this season, Horton added, including the avalanche that killed three and injured four in a heli-skiing group southwest of Invermere on Wednesday, Mar. 1.
“It’s following this pattern of a really tricky snowpack and I think it’s going to continue like that for the remainder of the season,” Horton said.
Interior Health issued a press release Friday, Mar. 3 urging extreme caution due to these elevated avalanche conditions.
“Being caught in an avalanche is a life-threatening situation that has already claimed twelve lives in the Interior Health region this season,” said Dr. Fatemeh Sabet, medical health officer, Interior Health. “There have been more than double the number of avalanche fatalities compared to the previous season and we are only halfway through the season.”
Conditions in areas with the deep persistent weak layer on Avalanche Canada’s forecasting map have been at considerable or worse, some fluctuations aside, for most of the winter.
“That specifically applies to alpine terrain, in upper tree line elevations where this layer has been more prevalent in the Purcells and Selkirks, so expect considerable dangers to persist at upper elevations for the foreseeable future,” Horton said.
As spring approaches warm weather and increased radiation from the sun on sunny days will also add stress to the snowpack. Weak layers become easier to trigger on warm, sunny days.
It is crucial if venturing into the backcountry to be aware of and respect these complex conditions and be disciplined in making terrain choices. Avalanche Canada’s advice is to avoid more high-consequence terrain. Stay away from the big slopes that have potential to produce large avalanches.
“The message is the same as it’s been for the last few weeks,” Horton said. “It’s tricky conditions, people heading out should have extra caution and be more conservative with where they’re travelling and have that critical training and equipment.”
Visit avalanche.ca for further details and up-to-date conditions.