Avalanche Canada Warning Service Manager Karl Klassen says that while he has no specific information as to what occurred in a deadly avalanche near Invermere on Saturday, he can speak to conditions in the area.
Avalanche Canada said the resulting “very large deep persistent slab” avalanche was 200 to 400 metres wide and ran for nearly 1,100 metres into a small lake.
“I don’t know what happened,” he said. “The police and coroner’s office are still investigating, but danger ratings are elevated in the Purcells in recent days and probably will continue that way.”
The problem is a weak layer of snow that formed back in October, he says.
“This fundamentally weak layer formed early in the season,” he said. “There have been several big avalanches reported. The weak layer is over-loaded after recent storms and warmer temperatures.”
This weak layer is especially prevalent in the Purcells, Klassen says.
“We are not really seeing it elsewhere in the province. The Purcells often have a snow pack that’s a bit more shallow. It’s the kind of layer that I would be cautious of. Our suggestion is to be quite cautious.”
Klassen says that it’s hard to predict whether the layer will persist all winter, but in his experience it can.
Current conditions in the Purcells are high in the Alpine and considerable at the tree line.
A high means very dangerous conditions and travel in the alpine is not recommended. Considerable also means dangerous conditions and careful snowpack evaluation, cautious route-finding and conservative decision making is essential.