Avalanche Forecast
Issued: Dec 12th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Wind Slabs.
rgoddard,
Avalanche Canada
Expect differing avalanche problems depending on where in our region you recreate today.
Wind slabs are the main concern in the eastern regions while a buried weak layer needs your attention in the west and central regions.
Plan your travel and terrain choices appropriately. Read our latest blog for ways of managing our avalanche problem.
Summary
Confidence
Avalanche Summary
Over the last few days, there has been an increase in avalanche activity in our region and in that of our nearest neighbours. Local operators have been able to trigger wind slabs and buried weak layers with the use of explosives producing large avalanches. There have been reports in the MIN of people accidentally triggering avalanches. Other signs of instability are being reported as well, such as seeing debris from avalanche, experiencing whumpfs and shooting cracks. Some MIN reports have witnessed lots of reactivity on the buried weak layer, 60 cm deep, in snowpack testing. Avalanches are failing mostly on the buried weak layer but wind slabs were also reactive. There was also an avalanche involvement to the immediate west of us that occurred from triggering the weak layer.
Snowpack Summary
Since Thursday night up to 20 cm has accumulated in some parts of our region. Much of this has been redistributed by strong westerly winds at most elevations. The new snow and new wind slabs are covering a variety of surfaces which will need time to bond properly. It is expected that the wind has built wind slabs upon wind slabs in some areas while in other areas the wind will have stripped away the majority of the snow.
Where the wind had less of an impact on the snow you can expect to find around 10 to 20 cm of soft snow sitting on 30 to 40 cm of more settled snow. Buried 45 to 65 cm down lies a weak layer comprising of surface hoar and facets. This layer has been shown to be reactive in snowpack tests and showed be kept on your radar for the time being. Further down the snow is sugary and faceted with a rain crust near the ground but this lower snowpack appears to be consolidating.
Total snowpack depths at treeline elevations are 75 to 155 cm.
Weather Summary
Monday Night
Clear clouds increasing, no accumulation, winds northeast 10 km/h, temperature -10 C at 1500 m.
Tuesday
Mostly cloudy, trace accumulation, winds west 10 km/h, temperature -8 C at 1500 m.
Wednesday
Cloudy with possible sunny periods, up to 3 cm accumulation in some places, winds southwest 10 km/h, temperature -8 C at 1500 m.
Thursday
A mix of sun and cloud, trace accumulation, winds northeast 10 gusting to 25 km/h, temperature -10 C at 1500 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
- Caution around convexities or sharp changes in terrain.
Problems
Persistent Slabs
Buried layers of surface hoar and facets exist 50 to 75 cm down and are showing reactivity in snowpack tests. Avalanches on this layer are possible where a cohesive slab exists above it.
This layer could be triggered by a heavy load caused by a rider in shallow snow areas, on convex rolls, or by the weight of a smaller avalanche.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Much of our region has been heavily wind-affected. Smaller micro features and cross-loaded terrain are expected to harbour wind slabs.
Small avalanches may trigger a bigger avalanche by 'stepping down' to the weak and faceted crystals buried deeper within the snowpack.
Aspects: North, North East, East, South East, South, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 13th, 2022 4:00PM
