Avalanche Forecast
Issued: Mar 12th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Wind Slabs.
ahanna,
Avalanche Canada
Watch for pockets of wind slab at upper elevations. Don't forget about a buried weak layer that remains triggerable.
Summary
Confidence
High -
Weather Forecast
Saturday night: Cloudy with snowfall, accumulation 2 to 5 cm, 20-30 km/h south wind, alpine temperature -5 C. Freezing level 900 m.
Sunday: Cloudy with snowfall, accumulation 2 to 5 cm, 20 km/h southwest wind, alpine temperature -3 C. Freezing level 1600 m.
Monday: Cloudy with snowfall, accumulation 5 to 15 cm, 40-60 km/h southwest wind, alpine temperature -3 C. Freezing level 1600 m.
Tuesday: Cloudy with snowfall, accumulation 5 to 15 cm, 40-60 km/h southwest wind, alpine temperature -3 C. Freezing level 1500m.
Avalanche Summary
No new avalanches reported on Thursday or Friday.
A rider triggered a persistent slab avalanche along the Duffey on Wednesday, occurring at 2000 m on a northeast aspect. Another suspected persistent slab avalanche was triggered by a rider on Tuesday in the north of the region. Both slabs were around 30 to 40 cm thick, resulting in small avalanches (size 1 to 1.5). It remains possible that humans could trigger this layer, where it exists.
Looking forward, wind slabs may begin to form on Friday and into the weekend, which may not bond well to underlying layers.
Snowpack Summary
Small amounts of new snow and southwest wind have likely formed small wind slabs in lee terrain features. The snow accumulates onto variable surfaces. On sun-exposed slopes and on all aspects at low elevations, the snow will build on a hard melt-freeze crust. Elsewhere, it will fall onto previously wind-affected snow at higher elevations and perhaps a thin layer of surface hoar or faceted snow in sheltered areas.
Around 30 to 60 cm deep, sugary faceted grains may be found around a melt-freeze crust that formed February in the north of the region (e.g., Duffey, Hurley). To date, the layer has been most prevalent on north to northeast aspects around 1900 to 2100 m. This layer should be treated as suspect anywhere it exists. Check out this forecaster blog for more info. Various crusts may be found in the south of the region (e.g., Coquihalla, Manning) but reports suggest they are bonding to the snowpack and are not an avalanche concern.
There are no deeper concerns at this time.
Terrain and Travel
- Be aware of the potential for large avalanches due to the presence of buried persistent weak layers.
- Although their spatial distribution is isolated, wind slabs are reactive.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
Problems
Persistent Slabs
Portions of the north of the region (e.g. Duffey, Hurley) have a a weak layer of faceted grains above a hard melt-freeze crust that is found 30 to 60 cm below the snow surface. A few avalanches over the past week have released on it, with more activity observed in the neighbouring Sea to Sky region. It has been most problematic on north to northeast aspects around 1900 m to 2100 m.
Aspects: North, North East, East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
New wind slabs have started to form as new snow accumulates with southwest wind. They may be small but reactive if they bond poorly to the old surface.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 13th, 2022 4:00PM
