Avalanche Forecast
Issued: Dec 8th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
zryan,
Avalanche Canada
Seek out wind sheltered terrain where you can avoid wind slabs and find great riding.
Summary
Confidence
Weather Forecast
Unsettled weather will continue over the next few days. On Friday, a strong pacific system will move into the northwest ranges bringing strong winds, rising freezing levels, and up to 20 cm of new snow.
Wednesday Overnight: Mainly cloudy with isolated flurries, up to 5 cm of accumulation. Moderate to strong westerly winds.
Thursday: A mix of sun and cloud with isolated flurries. Light accumulation with continued moderate to strong westerly winds at ridgetop. Freezing levels at valley bottom with alpine temperatures around -15 C.
Friday: Mainly cloudy with the next system incoming. Winds increasing strong to extreme at ridge top from the southwest. Freezing levels rising to around 500-1000m. 5-15 cm of new snow, heaviest in the afternoon and into the evening.
Saturday: Partially cloudy with light flurries, trace accumulation. Freezing levels at valley bottom with alpine temperatures around -10 C. Moderate to strong southwest winds at ridgetop.
Avalanche Summary
On Saturday, a size 3 avalanche was reported in the Hankin-Evelyn area, failing near the ground. This has us thinking about the potential for a deep persistent weak layer.
If you do head out in the backcountry, please share your observations to the Mountain Information Network!
Snowpack Summary
10-20 cm of new snow will continue to be redistributed by southwest winds into wind slabs in the alpine and treeline. These new wind slabs overlie older wind slabs from previous southwest winds and a variety of hard, wind effected surfaces.
Below 1400m, a thin rain crust exists below the new snow. There have been reports of faceting around this crust with recent cold temperatures. A spotty surface hoar layer has been reported down ~100cm in the alpine and treeline.
An early season crust can be found near the base of the snowpack. It has shown reactivity in the past week with large loads (explosives and cornice), creating large avalanches. We don't know how widespread this problem may be. With recent snow and wind we are definitely keeping an eye on it, and would be avoiding large features and areas with thin to thick snowpack transitions.
Snowpack depth at treeline ranges from 150-200 cm, with higher values in the western part of the region, tapering to the east.
Terrain and Travel
- Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
- Seek out sheltered terrain where new snow hasn't been wind-affected.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Problems
Wind Slabs
Westerly winds will continue to redistribute new snow forming wind slabs in the alpine and treeline. These wind slabs may overlie a weak layer of facets or a thin rain crust below 1300m. These weak layers will increase both the reactivity and propagation potential of wind slabs, particularly when a crust is present below.
Aspects: North, North East, East, South East, South.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
An early season crust near the base of the snowpack has shown reactivity in the past week with large explosives' and cornices. With recent snow and wind we are definitely keeping an eye on it, and would be avoiding large features and areas with thin to thick snowpack transitions.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 9th, 2021 4:00PM
