Avalanche Forecast
Issued: Jan 17th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Cornices, Deep Persistent Slabs and Wind Slabs.
ahanna,
Avalanche Canada
Give those big saggy cornices an extra wide berth. Many recent cornice falls have triggered deep slabs on the slopes below. Be mindful that sunshine can have a powerful effect on stability - and your desire to push into aggressive terrain.
Summary
Confidence
Weather Forecast
Sunday night: Clearing, light to moderate northerly ridgetop wind, freezing level 1100 m.
Monday: Sunny, light to moderate northerly ridgetop wind, freezing level 2000 m in the southwest, 1000 m further inland.
Tuesday: Sun and cloud with evening flurries developing, ridgetop wind building to strong southwest, freezing level 800 m.
Wednesday: Sun and cloud, light variable ridgetop wind, freezing level 600 m.
Avalanche Summary
Explosive control work targeting cornices on Friday and Saturday produced size 2 results, some triggering deep slabs in the rocky slopes below.
A widespread natural avalanche cycle up to size 3 occurred throughout the region during a storm last week. Several initiated as storm slab and stepped down to deeper weak layers resulting in very large (size 3-4) persistent slab avalanches.
Over a week ago now, a large (size 3) avalanche was remotely triggered by skiers on Cowboy Ridge near Whistler. The avalanche occurred on a north to northwest aspect at around 1900 m. The crown was up to 200 cm deep and was approximately 200 m wide. Check out this MIN for photos and more information. A similar avalanche was remotely triggered by skiers on a nearby westerly slope a few days before; check out this MIN for more info and photos.
Snowpack Summary
Ski quality in the extensively wind affected alpine has been widely referred to as chalky. Soft snow may be found in sheltered areas around treeline and may overlie a spotty layer of surface hoar. A widespread surface crust exists below 1900 m.
The snowpack is currently quite complex. A layer of sugary faceted grains above a hard melt-freeze crust from early December may be found down 100 to 200 cm. Just over a week ago, several large natural and human-triggered avalanches on this layer occurred, with the hot spots being around the Whistler backcountry.
Near the base of the snowpack, there may be faceted grains above a crust from early-November, which was identified as the failure layer in sporadic avalanche releases. At this depth, avalanches are large and destructive.
Terrain and Travel
- Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
- Avalanche hazard may have improved, but be mindful that deep instabilities are still present.
- In times of uncertainty conservative terrain choices are our best defense.
Problems
Cornices
Cornices have grown large, saggy and fragile. A few recent cornice falls have triggered avalanches on the slopes below. Many that haven't fallen are showing pull-away cracks.
Aspects: North, North East, East, North West.
Elevations: Alpine.
Likelihood
Expected Size
Deep Persistent Slabs
A couple of problematic layers may be found around 100 to 200 cm deep, including a weak layer of faceted grains above a melt-freeze crust. A few high-consequence avalanches have been triggered naturally and by riders recently near Whistler.
Read what a local guide has to say about these persistent weak layers here.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Previous wind has deposited recent snow into deeper slabs on leeward slopes at upper elevations. It remains a possibility for isolated wind slabs to react to human triggers.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 18th, 2021 4:00PM
