Avalanche Forecast
Issued: Dec 7th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs.
ahanna,
Avalanche Canada
New snow and wind will form fresh slabs at upper elevations. A couple of near-surface crusts offer slick sliding surfaces for avalanches. As the storm slab problem gets trickier, the easiest solution is to choose more conservative terrain.
Summary
Confidence
Weather Forecast
Tuesday night: New snow 10-20 cm. Strong southwest wind. Freezing level 1000 m.
Wednesday: Flurries up to 5 cm. Moderate westerly wind. Treeline high temperatures around -8. Freezing level 500 m.
Thursday: Flurries up to 5 cm. Light southwest wind. Treeline high temperatures around -9. Freezing level 500 m.
Friday: New snow 5-10 cm. Moderate southwest wind. Treeline high temperatures around -6. Freezing level 800 m.
Avalanche Summary
On Monday, small loose dry and soft slab avalanches were observed naturally up to size 1 and up to size 1.5 with skier and explosive loads.
On Sunday, a skier accidentally triggered a size 1 wind slab near a convex northeast aspect in the Whistler sidecountry. A few small solar triggered point releases were also observed on steep south aspects.
On Saturday, some loose dry sluffing and thin soft slab reactivity were observed in steep terrain and near ridge crests. The slide in this excellent MIN from Garibaldi Park appears to have initiated out of extreme terrain, breaking up quickly and entraining low density surface snow.
Snowpack Summary
10-20 cm of overnight snow fell amid strong wind, likely loading deeper deposits into lee features at upper elevations. The new snow may sit over a thin lens crust that formed when 10-15 cm of recent snow warmed up on Tuesday. This recent snow may be sitting over a weak layer of surface hoar crystals near or on a thick crust.
Faceting has been observed on the underside of this thick, shallowly buried rain crust. We will continue to monitor this layer as it becomes buried deeper. Deeper buried crusts near the base of the snowpack appear to be dormant for now.
Average snow depths at treeline are now likely closer to 150-200 cm, with 450+ cm above 1900 metres. Snowpack depths taper dramatically to below threshold very near the treeline/below treeline boundary.
Terrain and Travel
- Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
- Be aware of the potential for larger than expected storm slabs due to the presence of buried surface hoar.
- Be alert to conditions that change with elevation and wind exposure.
Problems
Storm Slabs
New snow and wind are forming fresh slabs. Where previous days' snow sits over a weak layer, slab avalanches could be larger than expected.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 8th, 2021 4:00PM
