Avalanche Forecast
Regions: Bonnington, Crawford, Grohman, Kokanee, Kootenay Boundary, Kootenay Pass, Moyie, Norns, Rossland, St. Mary, Valhalla, Ymir.
Triggering large avalanches is a serious concern as illustrated in this PHOTO BLOG.
Stick to low-angle slopes, avoid overhead hazards, and choose smaller objectives.
Confidence
Moderate
Avalanche Summary
Many very large (size 3.5) persistent slab avalanches occurred in the Selkirks on Monday to Wednesday. Most were natural and explosive-triggered, but there was also a notable size 3.5 avalanche remote-triggered from a ridgeline in the Bonningtons on Tuesday. A notable incident occurred in the south Purcells on Sunday.
Smaller storm slab avalanches also occurred over the past few days, but the persistent slab problem should dominate terrain choices.
Snowpack Summary
Surface conditions currently include settling powder, sun crusts, and lightly wind-affected snow in higher open areas.
A prominent crust is found 100 to 150 cm below the surface, with several potential weak layers above it including facets, surface hoar, and thin decomposing crusts. These layers continue to produce concerning avalanches across the region.
The snow below the crust is generally strong and bonded.
Weather Summary
Thursday Night
Mostly clear skies. 20 km/h southwest ridgetop wind. Treeline temperature -12 °C.
Friday
Mostly sunny with a few clouds. 30 km/h southwest ridgetop wind. Treeline temperature -3 °C.
Saturday
Mostly cloudy with up to 5 cm of snow in the Monashees and Selkirks and a mix of sun and cloud in the Purcells. 50 km/h southwest ridgetop wind. Treeline temperature -3 °C.
Sunday
Cloudy with 5 to 15 cm of snow. 40 km/h south ridgetop wind. Treeline temperature -5 °C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Use conservative route selection. Choose simple, low-angle, well-supported terrain with no overhead hazard.
- Avoid being on or under sun exposed slopes.
- Remote triggering is a concern, watch out for adjacent and overhead slopes.
Avalanche Problems
Persistent Slabs
Large avalanches on a 100 to 150 cm deep facet/crust layer are a serious concern. We have seen full-path avalanches, many remote-triggered. They are becoming less likely to trigger, but uncertainty and serious consequences remain.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 2.5 - 3.5