Avalanche Forecast
Regions: South Coast Inland.
Watch for pockets of fresh wind slab forming at upper elevations. Don't forget about a buried weak layer that remains triggerable.
Confidence
Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.
Weather Forecast
Sunday night: Snowfall 3-8 cm, 30-50 km/h southwest wind, alpine temperature -4 C. Freezing level 1500 m.
Monday: Snowfall 5-10 cm, 30-40 km/h southwest wind, alpine temperature -2 C. Freezing level 1700 m.
Tuesday: Snowfall 5-10 cm, 20-40 km/h southwest wind, alpine temperature -3 C. Freezing level 1500m.
Wednesday: Overnight snowfall around 5 cm then cloudy, 10-20 km/h southwest wind, treeline temperature -6 C. Freezing level 1400 m.
Avalanche Summary
No new avalanche observations since Wednesday when a rider triggered a persistent slab avalanche along the Duffey 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.
Snowpack Summary
Small amounts of new snow and southwest wind are likely forming wind slabs in lee terrain features. The new snow accumulates onto variable surfaces including a hard melt-freeze crust on solar aspects and low elevations, 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). The layer has been most prevalent on north to northeast aspects around 1900 to 2100 m. 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
- Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.
- Be aware of the potential for large avalanches due to the presence of buried persistent weak layers.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
Avalanche 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 slid on it last week, 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: Unlikely - Possible
Expected Size: 1 - 2.5
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: Possible - Likely
Expected Size: 1 - 1.5