Avalanche Forecast
Regions: Bonnington, Crawford, Grohman, Kokanee, Kootenay Boundary, Kootenay Pass, Moyie, Norns, Rossland, St. Mary, Valhalla, Ymir.
Recent storm snow continues to need time to stabilize. Carefully assess steep slopes at treeline and below, where a reactive surface hoar layer is more likely.
Confidence
Moderate
Avalanche Summary
A widespread avalanche cycle took place on Wednesday, with numerous skier and explosive-triggered avalanches reported across various elevations and aspects, up to size 2. These slab avalanches primarily failed in the upper 40 cm of recent storm snow.
A few avalanches appeared to fail on surface hoar crystals beneath the new snow, roughly 40 cm deep. This could indicate the presence of a persistent weak layer that may continue to be a concern moving forward.
Snowpack Summary
As much as 30 cm of recent snow has been redistributed by primarily southwest winds into deeper deposits in lee terrain features at higher elevations.
Below the new snow, a sun crust exists on south-facing terrain, buried in early December. While, a buried surface hoar layer exists in sheltered, shaded terrain. The surface hoar distribution and reactivity remain a significant source of uncertainty currently.
The lower snowpack is strong and bonded. Treeline snow depths range from 100 to 180 cm.
Weather Summary
Thursday Night
Cloudy with 2 to 6 cm of snow. 30 to 40 km/h southwest ridgetop wind. Treeline temperature -3 °C.
Friday
Mostly cloudy. 30 to 40 km/h southwest ridgetop wind. Treeline temperature -1 °C.
Saturday
Mix of sun and cloud with 0 to 2 cm of snow. 20 to 40 km/h south ridgetop wind. Treeline temperature +1 °C. Freezing level 2200 m.
Sunday
Mix of sun and cloud with up to 5 cm of snow overnight by Sunday morning. 20 to 40 km/h south ridgetop wind. Treeline temperature -4 °C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
- Stay off recently wind loaded slopes until they have had a chance to stabilize.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
Avalanche Problems
Storm Slabs
Storm and wind slabs continue to be a concern following the recent storm. A weak surface hoar layer or thin crust beneath the slabs may increase reactivity where it is present, causing instability to persist longer than expected.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible - Likely
Expected Size: 1 - 2