Though avalanche conditions should be predictable over the Christmas long weekend, Avalanche Canada noted there is still potential for danger.
James Floyer, public avalanche forecaster with Avalanche Canada said it’s been an interesting past weekend with some snowfall in the region around Cranbrook
“A lot of areas in the South Columbia region — including the Purcells, the South Rockies and the Lizard Range —had a very similar sort of situation where a reasonable amount of storm snow fell over the weekend. Depending if you’re in a wetter or dryer area it was 30-40 centimetres or 15-20 centimetres. It fell on a slippery crest.”
The snow fell on a crest with feathery crystals called surface hoar crystals.
“We get that sort of layer interface forming it can lead to a very good sliding layer and that’s what happened over the weekend,” he said.
He noted there were avalanche cycles reported, with some of the biggest in the Kootenay Boundary region where they had avalanches up to 2.5 — that’s half way up the Canadian Avalanche Scale.
“Size two is classified as sufficiently large to bury and injure or kill a person. So certainly sizeable enough to be taken seriously,” he said. “What we’re expecting is another pulse of precipitation coming through on Tuesday into Wednesday. It looks like it’s going to be a little bit less than what we had before so again slightly depending on where you are again.”
He said it would be about 10-20 centimetres of snow.
“Somewhere like Kootenay Pass is set to be on the higher end of that, whereas around the Cranbrook area that might be a bit lower — in the 10 cm region,” he said.
The snow will add new load to existing weaknesses.
He said those could be triggered by a snowmobiler, skier or other traveller in the mountains.
“That little extra pulse of precipitation for Tuesday into Wednesday will certainly elevate the danger as well. Whether we’ll see another widespread natural avalanche cycle is not as clear, and that will slightly depend on exact amounts.”
Floyer suspects some of the higher snow areas could see another avalanche cycle.
“If you’re only getting sort of 10 or 15 cm it’s less likely that you’ll see natural avalanches occur,” he said. “But it’s still primed for human triggering.”
He said the good news is when compared with some of the complex situations that can generate in the backcountry, this is a simple straightforward snow pack problem.
“There certainly is the instability there with the potential to catch somebody out that is going to exist through the Christmas period,” he said. “The certainly is the danger and potential to trigger an avalanche that could ruin someone’s day.”
Floyer said looking for avalanche activity on similar slopes can provide some information. Starting on smaller slopes and then working up to larger ones is also a good idea.
“And of course be wary around loaded ridge lines — anywhere the wind has had a chance to go off and over the ridge line and deposit on the slope below. Those areas are going to be more touchy than areas where the wind has scoured the slope a little bit.”
The public can submit information through Avalanche Canada’s website avalanche.ca. Up-to-date avalanche bulletins are also posted there.