Avalanche Forecast
Regions: Bonnington, Grohman, Kootenay Boundary, Kootenay Pass, Moyie, Norns, Rossland, St. Mary, Ymir.
Conditions are more complicated than what meets the eye. Fresh wind slabs formed at upper elevations. Riders may be drawn to more sheltered areas around treeline to avoid these wind slabs, but should consider that this is where the persistent slab problem has been most problematic to date. Keep your terrain choices conservative and don't let good riding lure you into more hazardous terrain.
Confidence
Moderate
Avalanche Summary
No significant avalanches were reported in the past couple days. Over the weekend Small skier and remotely triggered avalanches were reported. These avalanches were generally at treeline and failed on the mid November surface hoar layer.
Snowpack Summary
New snow and Southwest winds will likely have formed wind slab throughout the day on Thursday. Recent snow has buried a layer of surface Hoar in sheltered terrain and a sun crust on south facing slopes.
A concerning layer of surface hoar from mid November is buried down 40 to 60cm. This layer could become more reactive as slab properties above it increase with new snow and wind.
Snowpack depths average 80-160 cm in the alpine. Below treeline elevations are now above the threshold for avalanches in many areas.
Weather Summary
Thursday Night
5 to 10cm of new snow expected. Moderate southwest winds with a low of -7 at 1500m.
Friday
Mostly cloudy with a trace of new snow expected. moderate southwest winds with a high of -5 at 1500m.
Saturday
Cloudy with up to 10cm of new snow. Moderate southerly winds in the morning becoming light in the afternoon. High of -5 at 1500m.
Sunday
Flurries in the morning bringing 5cm of new snow and then clearing in the afternoon. High of -2 at 1500m. Light winds.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Remote triggering is a concern, watch out for adjacent and overhead slopes.
- Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
Avalanche Problems
Persistent Slabs
A surface hoar layer from mid November is buried down 40 to 60cm in the region. With the new snow and southwest winds on Thursday it is likely that this layer is approaching a tipping point where it will become more sensitive to rider triggering . Use extra caution at treeline where this layer is more prominent.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1.5 - 2.5
Wind Slabs
New wind slabs likely formed throughout the day on Thursday. Carefully assess for wind slab as you move through terrain and remember that wind slabs could trigger the mid November layer resulting in a larger and more destructive avalanche.
Aspects: North, North East, East, South East, South, West, North West.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 2