Avalanche Forecast
Regions: Bonnington, Crawford, Grohman, Kokanee, Kootenay Boundary, Kootenay Pass, Moyie, Norns, Retallack, Rossland, St. Mary, Valhalla, Whatshan, Ymir.
Continued snowfall will keep storm slabs reactive and stress buried weak layers. Conservative terrain choices are crucial.
Confidence
Moderate
Avalanche Summary
Storm slabs have produced many size 1 to 2 avalanches in recent days, including numerous human-triggered slabs in the top 30 cm and larger natural avalanches in alpine terrain.
Two large persistent slab avalanches occurred on Thursday: a skier-triggered size 2 in the Monashees and a natural size 3 in the Selkirks.
Expect continued storm slab activity on Sunday. Persistent slab avalanches will become likely as temperatures warm this week.
Snowpack Summary
Storm slabs will grow on Sunday with 10 to 15 cm of new snow adding to the 15 to 25 cm snow from the previous few days.
Several weak layers in the snowpack are currenlty concerns for triggering persistent slab avalanches:
Facets/surface hoar/crust from early March buried 40 to 70 cm,
Facets/surface hoar/crust from mid-February buried 60 to 100 cm, and
Facets/surface hoar/crust from late January buried 100 to 150 cm.
This complex snowpack combined with dynamic weather makes travel in avalanche terrain dangerous.
Weather Summary
Saturday Night
Mostly cloudy with 0 to 1 cm of snow. 30 km/h southwest ridgetop wind. Treeline temperature -5 °C.
Sunday
Cloudy with increasing snowfall rate and 10 to 15 cm of snow. 40 km/h southwest ridgetop wind. Treeline temperature -5 °C.
Monday
Snow transitioning to rain with 30 to 50 mm in the Monashees and Selkirks and 10 to 20 mm in the Purcells. 60 km/h southwest ridgetop winds. Treeline temperature +2 °C. Freezing level rising to 2400 m.
Tuesday
Cloudy with 10 to 20 mm of rain and then clearing skies in the afternoon. 20 km/h southwest ridgetop wind. Treeline temperature +6 °C. Freezing level 2700 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Use conservative route selection. Choose simple, low angle terrain with no overhead hazard.
- Avoid freshly wind-loaded terrain features.
- Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
Avalanche Problems
Storm Slabs
Another 10 to 15 cm of new snow will add the existing storm storm slab problem. Wind-loaded slopes will be especially dangerous.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely - Very Likely
Expected Size: 1 - 2.5
Persistent Slabs
Several persistent weak layers exist in the upper metre of the snowpack. Small avalanches in motion may trigger these deeper layers creating large and destructive avalanches.
Aspects: North, North East, East, West, North West.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 2 - 3