Avalanche Forecast
Regions: Bonnington, Crawford, Grohman, Kokanee, Kootenay Boundary, Kootenay Pass, Moyie, Norns, Retallack, Rossland, St. Mary, Valhalla, Whatshan, Ymir.
Storm snow remains triggerable at higher elevations. Uncertainty around a buried weak layer is best managed through conservative terrain choices.
Confidence
Moderate
Avalanche Summary
Many storm slab and loose wet avalanches released during the intense rainy conditions earlier this week. Natural avalanche activity likely tapered on Friday.
We're uncertain on whether avalanches could still release on the surface hoar layer described in the Snowpack Summary, so travelling cautiously until there is evidence it is bonding is a good strategy.
Snowpack Summary
20-50 cm of snow sits on a melt-freeze crust. Below, the moist snowpack is slowly refreezing from the top down.
A weak layer of surface hoar buried 50 cm deep has been observed to have miraculously survived the rain. With plenty of uncertainty, we think that it may have been largely cleaned out by avalanches during the storm, but lingers in isolated features. As the overlying crust becomes thicker and more supportive, the bridging effect will reduce the likelihood of triggering this layer, where it exists. In the meantime, we recommend treating this layer as suspect while we await more observations.
Snowpack depths are generally 60-110 cm at treeline, tapering quickly with elevation.
Weather Summary
Saturday night
5-15 cm of new snow. Moderate to strong southerly wind. Freezing level valley bottom.
Sunday
2-5 cm of new snow. Moderate southwest wind. Treeline high temperature around -2. Freezing level 900 m.
Monday
Mix of sun and cloud. Light northwest wind. Treeline high temperature around -2. Freezing level 900 m.
Tuesday
Mix of sun and cloud. Light to moderate southwest wind. Treeline high temperature around -3. Freezing level 600 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Closely monitor how the new snow is bonding to the old surface.
- Be aware of the potential for larger than expected storm slabs due to the presence of buried surface hoar.
- Uncertainty is best managed through conservative terrain choices at this time.
- Early season avalanches at any elevation have the potential to be particularly dangerous due to obstacles that are exposed or just below the surface.
Avalanche Problems
Storm Slabs
Storm slabs may remain triggerable by riders, especially where:
it sits over wet snow rather than a crust, over a layer of surface hoar
wind has redistributed the recent snow into leeward terrain features on north and east aspects
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 1 - 2