New snow and wind are creating very dangerous conditions. Travel in avalanche terrain at alpine and treeline elevations is not recommended.
30 to 80 cm of new snow has formed reactive storm slabs, especially on wind-loaded slopes. Storm and wind slab avalanches may step-down to deeper weak layers and initiate large and destructive avalanches.
A layer of large and weak facets sits near the base of the snowpack. This layer is most prominent in upper treeline and lower alpine elevations. Storm slab avalanches could step down to this layer initiating very large avalanches. Riders are most likely to trigger an avalanche on this layer in steep, shallow terrain.
Heavy snow is causing an ongoing natural avalanche cycle that started on Thursday and will likely continue into Saturday morning. Reports from Thursday indicate storm slabs were very reactive to snowmobile traffic around Pine Pass, producing many size 1 to 1.5 storm slab avalanches that propagated widely. With additional snow, we expect storm slab avalanches to be much larger on Saturday. Human-triggered avalanches will be very likely on steep slopes and natural avalanches will likely continue on wind-loaded slopes. Storm slab avalanches could step down to the facets near the base of the snowpack, producing very large avalanches. See more on the potential of triggering deeper weak layers Forecasters' Blog.
Stormy weather over the past few days has brought 50 to 80 cm of new snow around Pine Pass and 30 to 50 cm around Tumbler Ridge and Kakwa. Warm windy weather has caused this storm to settle into reactive slabs. The storm snow sits on previously wind-affected snow. Below this, a melt-freeze crust is found on sun-exposed slopes and everywhere below 1600 m.
Several crust/facet/surface hoar layers exist in the upper and middle portions of the snowpack. Recent observations suggest these layers are not as concerning as in neighbouring regions.
The most concerning persistent weak layer is at the base of the snowpack from large and weak facets formed in November. This layer is widespread and most likely problematic in steep, rocky alpine terrain.
Friday night
Storm eases off with another 10 to 15 cm around Pine Pass and 5 cm around Tumbler Ridge and Kakwa, 40 to 60 km/h southwest wind, treeline temperatures drop to -6 °C.
Saturday
Mostly cloudy with isolated flurries brining trace amounts of snow, sunny breaks possible in the afternoon, 30 to 50 km/h southwest wind, treeline temperatures warm to -3 °C.
SundayCloudy with snowfall, 5 to 15 cm, 40 to 60 km/h southwest wind, treeline temperatures around -5 °C
MondayCloudy with snowfall, 5 to 15 cm, 50 to 70 km/h southwest wind, treeline temperatures around -3 °C
More details can be found in the Mountain Weather Forecast.
