Avalanche Forecast
Issued: Jan 18th, 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.
shorton,
Avalanche Canada
Avalanche conditions are improving, but lingering cornices, wind slabs, and deep persistent slabs warrant careful terrain selection.
Summary
Confidence
Weather Forecast
MONDAY NIGHT: Clear skies, light to moderate north wind, treeline temperatures around -1 C, freezing level around 1300 m.
TUESDAY: Increasing cloud and wind throughout the day as temperatures drop, sunny in the morning with light west wind and treeline temperature around -2 C then some light snowfall in the afternoon with strong southwest wind as treeline temperatures drop to -4 C.
WEDNESDAY: Mix of sun and cloud, light variable ridgetop wind, treeline temperatures around -5 C.
THURSDAY: Cloudy with some light flurries, light wind, treeline temperatures around -5 C.
Avalanche Summary
A few small wind slab and wet loose avalanches were reported on Sunday and Monday. Explosive control targeting cornices on Friday and Saturday produced size 2 results, some triggering deep slabs on the rocky slopes below.
There has been significant deep persistent slab activity this month. During a widespread avalanche cycle last week, several storm slabs stepped down to deeper weak layers resulting in very large (size 3-4) deep persistent slab avalanches (see these photos from Panorama Ridge). On Jan 9, 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. See this MIN for photos and more information. A similar avalanche was remotely triggered by skiers on a nearby westerly slope a few days before (see this MIN).
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 and on south-facing slopes.
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 has also been identified as the failure layer in sporadic avalanche releases.
Terrain and Travel
- Use ridges or ribs to avoid areas of wind loaded snow.
- 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.
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
Shifting wind has deposited snow into deeper slabs on leeward slopes. This problem can be managed by navigating around wind affected slopes, but keep in mind this is not the only problem in the snowpack right now.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 19th, 2021 4:00PM
