The snowpack in B.C.’s Interior is in a precarious state and human-triggered avalanches are currently considered likely in the backcountry, officials say.
Conditions have prompted a Special Public Avalanche Warning (SPAW) for recreational backcountry users that goes into effect immediately and will stay in place until Monday, Jan. 2.
“The storm cycles that hit western Canada over the past weekend added significant snow on top of an exceptionally weak lower snowpack,” Simon Horton, senior forecaster for Avalanche Canada, said in a press release.
“This has brought the conditions to a tipping point where dangerous avalanches are likely.”
Horton said avalanche danger ratings may start to decrease as the weather improves, but there will still be a chance of triggering a large avalanche.
The snowpack was already weak because of a prolonged cold and dry start to the winter. It created a number of persistent weak layers in the snowpack across the interior ranges of B.C. and the recent storm and warming temperatures have now destabilized that weak snowpack, making large, human-triggered avalanches likely.
“Incidents that we’ve seen have involved avalanches up to size three, which is what we’d call a very large avalanche. Capable of destroying a car on the highway, so definitely has the potential to bury, injure or kill someone,” said Avalanche Canada forecaster Colin Garritty.
The warning region includes most of B.C.’s Columbia Mountains, Glacier and Mount Revelstoke National Parks, as well as the Northern Rockies. The SPAW extends from the southern boundaries of the Purcell Wilderness Conservancy and Kokanee and Valhalla Provincial Parks to Williston Lake north of Pine Pass and Mackenzie.
One of the causes for these unstable snowpack layers in the Interior is the 30 C temperature fluctuation over the past week and a half.
“It was in that transition from that cold dry arctic air to warm moist conditions where we saw a lot of impacts. We saw snow changing to rain and we saw freezing rain develop as well,” said Environment Canada meteorologist Alyssa Charbonneau.
Making conservative terrain choices can help manage this risk. Sticking to lower-angle slopes and choosing smaller objectives that minimize the consequences of an avalanche are examples of how to reduce the risk.
Backcountry users should always check the avalanche forecast at www.avalanche.ca. Everyone in a backcountry party needs the essential rescue gear—transceiver, probe, and shovel—and the training to use it.
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