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.
lbaker,
Avalanche Canada
Use extra caution at treeline where triggering a persistent slab is more likely. This layer will be easier to trigger on exposed slopes where wind slabs could have formed over surface hoar.
Read our featured blog on understanding how to manage a persistent slab problem when traveling in the backcountry.
Summary
Confidence
Moderate
Avalanche Summary
On Sunday operators in the region reported a skier accidental persistent slab avalanche, size 2, on the mid-November layer.
Please continue to share any observations of photos on the Mountain Information Network!
Snowpack Summary
Variable winds throughout this region has redistributed the 20-40 cm of snow received last week into pockets of wind slab at higher elevations. In sheltered areas without wind effect loose dry snow can still be found.
The snowpack below this is generally weak. A layer of surface hoar, facets, and/or melt-freeze crust can be found down 40 to 60cm. This layer is most concerning at 1900m and below.
Snowpack depths range from 60cm at treeline to 140 cm in the alpine. Below treeline the snowpack is thin and faceted (weak) making it a challenge to access terrain in many areas without damaging your sled.
Weather Summary
Monday Night
Clear skies with northerly ridge winds 25 km/hr. Alpine temperatures, low of -10.
Tuesday
Mainly clear in the morning, becoming cloudy in the afternoon with isolated flurries, 2 cm accumulation. Northerly ridge wind 25 - 40 km/hr. Alpine temperatures, high of -10.
Wednesday
A mix of sun and cloud. Northwesterly ridge winds 40 km/hr. Alpine temperatures, high of -7.
Thursday
Clear skies. Northwesterly ridge winds 25 - 40 km/hr. Alpine temperatures, high of -8.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
- Seek out sheltered terrain where new snow hasn't been wind-affected.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
Problems
Persistent Slabs
A layer of concern formed in mid-November is composed of faceted grains, surface hoar, and/or a hard crust and can be found down 40 to 60 cm. Each incremental snowfall and wind event is adding an additional load bringing the weak layer closer to its tipping point. As a cohesive slab builds above the weak layer it could quickly become reactive to natural or human triggers.
Read our newest blog to learn more about this concerning layer and how to manage it.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Wind Slabs
As the wind changes direction it is possible that wind slab could be found on all aspects in exposed terrain at treeline and above.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 13th, 2022 4:00PM
