Variable across BC
If you are a winter backcountry traveller, take a minute to check out Avalanche Canada’s website. They issued a SPAW (Special Public Avalanche Warning) from Feb 29th to Mar 7th. Upon review, you will likely note the incredible diversity of avalanche conditions currently being observed across BC. Although colourful, this variety of conditions is problematic as backcountry riders plan their next excursions. While the Sun Peaks/Kamloops region currently sits in one of the few “moderate” (heightened avalanche conditions on specific terrain features) zones, one doesn’t need to travel very far east, north or west to find yourself either in a “considerable” (dangerous avalanche conditions) zone or “high” (very dangerous avalanche conditions) zone.
To summarize our winter, we started with very low precipitation amounts and generally warmer-than-average weather, although we did experience a few cold snaps. January continued to be relatively dry with a few smallish, short-lived snowfall periods; thank goodness for those. The lower-than-normal snowpack helped to create an early-season widespread, persistent weak layer(PWL) of facets near the base of the snowpack. Due to a lack of significant snow load on that weak layer, our region didn’t experience very many widespread issues. Other parts of BC were not so fortunate; the added snow load in the different areas increased the hazard.
Things seemed to be settling down until we experienced rainfall to mountaintops and very warm temps in early February. This combination of rain and warming temps predetermined the formation of a 10-20 cm crust, and a weak layer of facets eventually formed above the crust. All was relatively calm until most regions in BC received a crazy amount of snow in a short period at the end of Feb., I.e. the snowpack at the Little Bear weather station in the Coquihalla climbed from 159 cm on Feb 25th to 265 cm on Feb 29th. The rapid loading put a lot of stress on the buried weak layer(s), creating a widespread avalanche cycle. In many regions of BC, we now have a snowpack with multiple, persistent, weak layers under a significant load. These can be very reactive to natural or human-triggered loading, including smaller avalanches stepping down to deeper PWLs. Many backcountry travellers have noted the “propagation” quality of the current snowpack; avalanches can be remotely triggered from a significant distance.
Be well prepared if you plan to head out into the backcountry. Ensure your riding partners are prepared, have the right equipment, and know how to use it. Understand what the avalanche danger ratings mean, particularly High – “natural avalanches are likely, human-triggered avalanches are very likely,” Considerable – “natural avalanches are possible, human-triggered avalanches are likely” and Moderate – “natural avalanches unlikely, human-triggered avalanches possible.”
Please stay diligent as we head into the later part of a very interesting winter of variable weather. There are numerous resources that you may find handy. Avalanche Canada’s Avaluator is a made-in-Canada, rules-based decision-making planning tool which many find helpful. The Dangerator is a similar valuable tool in areas that have not yet been rated, utilizing the Avalanche Terrain Exposure Scale.
The riding conditions are excellent right now, with high-quality powder conditions. If you utilize good safety habits and are well-prepared, you can enjoy safe, rewarding backcountry experiences.
Take good care.