Avalanche Forecast
Regions: East Purcell, Purcells, West Purcell.
Avoid steep, rocky, wind-affected terrain where triggering buried weak layers is most likely. Small avalanches in motion or cornice failures may also trigger these deeper layers.
Confidence
Moderate
Avalanche Summary
On Tuesday, a natural size 2 persistent slab was observed in the alpine which failed on a weak layer from mid-February down 70 cm. Explosives triggered two very large deep persistent slab avalanches in the Western Purcells, two persistent slab avalanches near Invermere which stepped down to deeper layers, and two storm slabs in the alpine.
On Monday, a naturally triggered size 3 persistent slab was reported on an east-facing alpine bowl near Invermere.
Snowpack Summary
30 - 50 cm of recent storm snow overlies a crust on sunny slopes and lower elevations, and surface hoar or facets on sheltered and shady upper elevations. Southwesterly wind formed slabs on lee features at treeline and above.
Several persistent weak layers consisting of a crust, facets, and/or surface hoar from February and January remain a concern. They are down 50 to 100 cm in most areas.
The bottom of the snowpack is composed of large facets in most areas. There is evidence that this layer is becoming reactive again, and some very large avalanches have failed on this layer recently.
Weather Summary
Wednesday Night
Partly cloudy with a chance of flurries. 5 to 15 km/h southwest ridgetop winds. Treeline temperature -10 °C. Freezing level valley bottom.
Thursday
Mostly cloudy with a chance of flurries. 10 to 20 km/h southwest ridgetop winds. Treeline temperature -3 °C. Freezing level 1600 m.
Friday
Mostly cloudy with light snowfall 3-6 cm. 20 to 30 km/h southwest ridgetop winds. Treeline temperature -2 °C. Freezing level 1700 m.
Saturday
A mix of sun and cloud. 15 to 25 km/h northwest ridgetop winds. Treeline temperature -3 °C. Freezing level 1600 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid steep, rocky, and wind-affected areas where triggering slabs is more likely.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Be aware of the potential for large, destructive avalanches due to deeply buried weak layers.
Avalanche Problems
Persistent Slabs
Triggering buried weak layers is most likely in wind-affected terrain on northerly and easterly aspects. Small avalanches in motion may trigger these deeper layers creating very large and destructive avalanches.
Aspects: North, North East, East, West, North West.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1.5 - 3
Wind Slabs
30-50 cm of recent snow and southwest wind formed wind slabs on lee slopes at treeline and above
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 2
Deep Persistent Slabs
There is evidence that weak layers near the bottom of the snowpack are starting to wake up. Explosives and smaller avalanches in motion have both triggered this deep weak layer recently resulting in very large avalanches.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Unlikely - Possible
Expected Size: 2 - 3.5