Avalanche Forecast
Issued: Dec 8th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
rgoddard,
Avalanche Canada
Updated 8 am: Overnight snowfall and wind are forming fresh storm slabs and adding load to a buried weak layer.
Keep your terrain choices conservative and assess conditions while you travel. Watch and feel for signs of instability such as whumpfing, cracking, and new avalanches.
Summary
Confidence
Moderate
Avalanche Summary
No new natural avalanches observed since the weekend. Avalanches triggered with explosives, that were focused on wind slabs, were reported by local operators. These were small size one avalanches.
This past Sunday, a MIN report from Tunnel Creek reported reactivity in a snowpack test on the Mid-November layer on a south aspect. They also observed a large natural avalanche on a west-facing slope at treeline.
With continued moderate to strong winds and slightly warmer temperatures, wind slabs may be reactive. Loose-dry avalanches (sluffing) of the surface snow from steep slopes and terrain features should also be expected.
Snowpack Summary
In less than a week, about 40 cm of low-density snow has fallen. Southwesterly winds have redistributed much of this snow, building fresh wind slabs. In sheltered terrain, slightly warmer temperatures may start to consolidate the recent snow into more of a slab.
The middle of the snowpack consists of weak sugary layers of facets and surface hoar. A widespread rain crust remains near the ground, at treeline, and below treeline.
At treeline, snowpack depths vary from 120-200 cm.
Weather Summary
Thursday Night
Mainly cloud, 5 cm accumulation, winds southwest 20 gusting to 45 km/h, temperature -6 C at 1500 m.
Friday
Cloudy with possible sunny periods, 2 cm accumulation, winds southwest 15 gusting to 35 km/h, temperature -4 C at 1500 m.
Saturday
Mainly cloudy, trace accumulation, winds south 10 km/h, temperature -5 C at 1500m.
Sunday
Cloudy with sunny periods, 3 cm accumulation, winds south 10 km/h, temperature -3 C at 1500 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
- Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
- If triggered, storm slabs in-motion may step down to deeper layers and result in very large avalanches.
- The likelihood of deep persistent slab avalanches will increase with each day of warm weather.
Problems
Storm Slabs
Westerly, switching to the southwest, winds combined with new snow build reactive wind slabs in the alpine and open areas at treeline.
Small avalanches in the upper snowpack could trigger deeper weak layers, creating a larger-than-expected avalanche.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Buried layers of surface hoar and facets have been reactive to human triggers in recent days. Reactivity has been observed in sheltered areas at treeline, where the surface hoar may be preserved, and in wind-loaded areas at upper elevations, where a cohesive slab has been formed above.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 9th, 2022 4:00PM
