Avalanche Forecast

Wednesday night: Cloudy, isolated flurries with a trace of snow, light to moderate northwest winds, alpine temperature -11 C.

Thursday: Mostly cloudy, scattered flurries with a trace of snow, light northwest winds, alpine high temperature -6 C.

Friday: Partly cloudy, isolated flurries with a trace of snow, light variable winds, alpine high temperature -5 C. 

Saturday: Cloudy, 5-15 cm of snow, light northeast winds, alpine high temperature -5 C. 

Since the weekend storm, there have been several reports of failing cornices and small wind slabs. See this MIN report for a helpful illustration. Explosive triggers have also released several large avalanches breaking on deeply buried weak layers on a variety of aspects above 2200 m. This activity is a good reminder that this layer remains a problem in the region. Easier-to-trigger wind slab avalanches or cornice fall may have the potential to step-down to this layer.

During the weekend storm, numerous size 2-3.5 slab avalanches released naturally. A few were thought to have stepped down to deeper layers. These avalanches primarily occurred on leeward aspects at treeline and alpine elevations. Below tree line, wet loose avalanches ran naturally during the warm temperatures on Saturday. 

Incremental snow and wind is adding to previous wind-loading in the alpine and at treeline. Where the snow is being drifted and stiffened by wind, human-triggered avalanches may be possible. Cornices are large and looming and may be reaching their breaking point.

40-60 cm of snow fell during the weekend storm above 1900 m. Extreme winds originating from the southwest and shifting to the northwest created a tricky loading pattern at treeline and above and accelerated cornice growth. 

Below 1900 m, 10-20 cm snow may cover a crust that formed during the storm from warm temperatures and rain. The snow above this crust is well-bonded and gaining strength.  

A weak layer of surface hoar may still be found about 90 cm deep around Golden and Kimberley, 50 cm deep around Invermere, and 130 cm deep along Kootenay Lake. As usual for the Purcells, the base of the snowpack contains basal facets. It remains possible to trigger these deep weak layers in shallow rocky start zones or from a heavy trigger such as a cornice fall. 

• Recent wind has varied in direction so watch for wind slabs on all aspects.
• Seek out wind sheltered terrain below treeline where you can avoid wind slabs and find great riding.
• Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
• If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.