Avalanche Forecast
Regions: Bonnington, Crawford, Grohman, Kokanee, Kootenay Boundary, Kootenay Pass, Moyie, Norns, Retallack, Rossland, St. Mary, Valhalla, Whatshan, Ymir.
Rising temperatures are creating very dangerous avalanche conditions and terrible riding quality. No reason to go near avalanche terrain.
Confidence
Moderate
Avalanche Summary
Numerous storm slab avalanches size 1 to 2 have been reported daily over the last few days, including numerous human-triggered slabs in the top 30 cm and larger natural avalanches in alpine terrain.
A few very large natural and artificially triggered persistent slab avalanches size 3 to 4(!) were reported over the weekend. Large, destructive persistent slab avalanches will become increasingly likely as temperatures warm this week.
Snowpack Summary
30 to 50 cm of heavy, moist snow from Monday sits over a complex snowpack.
Several weak layers in the snowpack are currently concerns for triggering persistent slab avalanches:
Facets/surface hoar/crust from early March buried 50 to 80 cm deep,
Facets/surface hoar/crust from mid-February buried 70 to 100 cm deep, and
Facets/surface hoar/crust from late January buried 100 to 150+ cm deep.
This complex snowpack combined with dynamic weather makes travel in avalanche terrain dangerous.
Weather Summary
Monday night
2 to 8 cm of snow above 2000 m, light rain below. 20 to 40 km/h southwest ridgetop winds. Treeline temperature +2 °C. Freezing level 2000 m, rising to 2400 m.
Tuesday
Clearing skies in the afternoon. 20 to 30 km/h southwest ridgetop wind. Treeline temperature +4 °C. Freezing level rising to 2600 m.
Wednesday
Sunny. 20 to 30 km/h southeast ridgetop wind. Treeline temperature +10 °C. Freezing level 3200 m.
Thursday
Cloudy with rain turning to snow. 20 to 40 km/h northwest ridgetop wind. Treeline temperature 0 °C. Freezing level falling to 1800 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- A moist or wet snow surface, pinwheeling, and natural avalanches are all indicators of a weakening snowpack.
- Be aware of the potential for large avalanches due to buried weak layers.
- Avoid the runout zones of avalanche paths. Avalanches could run full path.
- Only the most simple non-avalanche terrain with no overhead hazard is appropriate at this time.
Avalanche Problems
Loose Wet
Wet storm snow is primed for loose wet avalanches as temperatures continue to rise.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Very Likely
Expected Size: 1 - 2
Storm Slabs
Heavy, wet storm slabs will likely be reactive as temperatures rise.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Very Likely
Expected Size: 1 - 2.5
Persistent Slabs
Several persistent weak layers exist in the upper metre of the snowpack. These layers will likely become increasingly active in the coming days as the snowpack warms and weakens.
Aspects: North, North East, East, West, North West.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 2 - 3