Avalanche Forecast
Issued: Dec 4th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
zryan,
Avalanche Canada
Investigate the effect of recent strong winds on the snowpack. If triggered, wind slabs have the potential to entrain into the faceted lower snowpack, creating large avalanches.
Avoid steep, wind-loaded terrain and continually assess conditions as you travel.
Summary
Confidence
Low
Avalanche Summary
On Saturday, a few, small (size 1) skier-triggered wind slabs occurred at treeline and below treeline.
A weak layer of surface hoar continues to be a concern. Avalanches up to size 2 were last reported on this layer on November 29th, believed to fail on the surface hoar before 'stepping down' to weak and sugary facets near the base of the snowpack. Check out this MIN report for more details.
Looking forward, we expect human-triggered wind slab avalanches to remain possible at all elevation bands. These slabs have the potential to 'step down' to deeper layers, resulting in large avalanches.
We have very few eyes out there. If you do get out please consider reporting in the MIN.
Snowpack Summary
Strong southwest winds have redistributed recent snowfall into dense wind slabs in the alpine, treeline, and in exposed areas below treeline. In the alpine, many slopes may have been stripped back to early-season layers or rock. In sheltered terrain new wind-affected snow sits above more faceted (sugary, weak) snow which may not bond well. Cold temperatures have weakened and faceted the snowpack as a whole. A rain crust sits near the ground.
Total snowpack depths at treeline elevations are 50-80 cm.
Weather Summary
Sunday night
Cloudy with snowfall, trace to 3cm accumulation. Easterly wind 10-20 km/h at ridgetop. Treeline temperatures drop to -13 C.
Monday
Cloudy with snowfall, up to 5 cm of accumulation. Westerly wind 20-50 km/h at ridgetop. Treeline temperatures reach a high of -9 C.
TuesdayCloudy with snowfall, up to 5 cm of accumulation. Westerly wind 20-50 km/h at ridgetop. Treeline temperatures reach a high of -10 C.
WednesdayA mix of sun and cloud. Westerly wind 30-60 km/h at ridgetop. Treeline temperatures reach a high of -5 C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Keep your guard up at lower elevations. Wind slab formation has been extensive.
Problems
Wind Slabs
Strong southwest winds have formed dense wind slabs on north and easterly facing slopes. Avoid snow that feels drum like or hollow.
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, North West.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
A buried layer of surface hoar and facets have been reactive in nearby areas. This layer is widespread throughout the Rockies. It will be most reactive where the snow above these layers acts as a slab (as opposed to loose snow) such as wind loaded areas.
Observations on this layer are currently limited. In times of uncertainty such as this, our best defense is to keep terrain choices conservative and reduce your exposure to avalanche terrain where possible.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 5th, 2022 4:00PM
