CALGARY – An increased danger rating in Alberta’s backcountry is slowing the number of skiers, snowboarders, snowshoers and climbers venturing out.
“Our largest concern and a problem we have in the snowpack is a persistent slab,” said Aaron Beardmore, a visitor safety specialist with Parks Canada.
A slab is a block of snow that sits on top of a weak layer in the snow. There’s currently about 60 centimetres of snow on top of one such weak layer of snow that fell Jan. 6.
“The snow crystals of that layer… are inherently quite weak. They’re persistent in the sense that they don’t break down in the snow pack very easily, so they linger. The more snow that you put on top of it, the greater potential you have for larger avalanches,” said Beardmore.
The avalanche rating climbed to considerable in the alpine and treeline of Kananaskis Country, Banff Yoho & Kootenay National Park as well as Little Yoho this week.
The increase follows weeks of relative stability in those areas and what backcountry enthusiasts refer to as the “green block” – when all elevations are rated as low risk.
It’s unusual in Alberta’s Rockies – the variable weather often creates complex snowpacks.
But mountain guides say there’s hope conditions will soon improve once again.
“We’re coming out the other side of a recent storm. During the peak of the storm cycle… we had warmer temperatures and an increasing snow load. We saw that layer becoming very reactive naturally and very especially reactive to human triggered,” said Beardmore. “Now we’re coming out the other side of that. We’ve seen the temperatures decrease – it’s gotten a little colder which has the tendency to tighten things up a little bit.”
While the natural avalanche cycle is expected to become less active, this level of risk poses problems – especially for those inexperienced with avalanche safety.
“In a considerable danger rating we urge people to be quite cautious… there’s still the potential for large avalanches to occur but you just don’t see the immediate feedback of a high avalanche cycle where there’s avalanches occurring naturally. So, it’s a very tricky condition right now,” said Beardmore.
Experts recommend reading avalanche bulletins carefully and making informed decisions before heading out.
© 2016 Shaw Media