Avalanche Forecast
Regions: Bonnington, Crawford, Grohman, Kokanee, Kootenay Boundary, Kootenay Pass, Moyie, Norns, Retallack, Rossland, Valhalla, Whatshan, Ymir.
Sticking to simple or non-avalanche terrain is recommended while the storm snow settles and stabilizes.
Avoid overhead hazard, especially during periods of sun.
Confidence
High
Avalanche Summary
A widespread region-wide avalanche cycle of natural, human and explosive-triggered avalanches occurred during the stormy weather over the last few days. Slabs were observed at all aspects and elevation zones, and reached up to size 3 (very large). While most were storm slabs, a significant number also failed on persistent weak layers.
Snowpack Summary
40 to 60 cm of recent snow has formed widespread storm slabs that are slowly settling and stabilizing. Southwesterly winds may have built especially reactive slabs on lee north through east facing slopes near ridgetops.There is potential for the new snow to overload deeper persistent layers in the upper to mid snowpack, causing storm slabs to step down. These layers include:
Facets/surface hoar/crust from early March buried 40-70 cm.
Facets/surface hoar/crust from mid-February buried 60-100 cm
Facets/surface hoar/crust from late January buried 100-160 cm.
The rest of the snowpack is well settled with no other layers of concern.
Weather Summary
Sunday Night
Cloudy with 1 to 8 cm of snow. 25 to 30 km/h south ridgetop wind. Treeline temperature -8 °C.
Monday
A mix of sun and cloud. 10 to 20 km/h variable ridgetop wind. Treeline temperature -5 °C.
Tuesday
Mostly sunny. 20 to 30 km/h northwest ridgetop wind. Treeline temperature -5 °C.
Wednesday
A mix of sun and cloud. 30 to 40 km/h south ridgetop wind. Treeline temperature -3 °C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be aware of the potential for human triggerable storm slabs at lower elevations, even on small features.
- Remote triggering is a concern; avoid terrain where triggering overhead slopes is possible.
- Avoid steep, sun-exposed slopes when the air temperature is warm or when solar radiation is strong.
- Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
Avalanche Problems
Storm Slabs
Up to 60 cm of recent snow has formed widespread storm slabs that need a few days to bond. The new snow will be especially reactive on wind-loaded slopes and on sunny slopes during periods of solar radiation.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely
Expected Size: 1 - 2.5
Persistent Slabs
Several persistent weak layers exist in the upper meter of the snowpack. Storm slabs or wet loose sluffs in motion may trigger these deeper layers creating larger than expected avalanches.
Aspects: North, North East, East, West, North West.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 2 - 3
Loose Wet
Wet loose avalanches will be likely on sun-exposed slopes. Avoid overhead hazard from steep sunny faces during the warmest parts of the day.
Aspects: South East, South, South West, West.
Elevations: All elevations.
Likelihood: Likely - Very Likely
Expected Size: 1 - 2