Avalanche Forecast
Regions: Dogtooth, East Purcell, Purcells.
Rising temperatures are creating very dangerous avalanche conditions. Large, destructive natural avalanches are likely. Avoid avalanche terrain.
Confidence
High
Avalanche Summary
Natural persistent slab avalanche activity has been observed throughout the region over the last week. On Monday, a few size 2 to 2.5s were observed between Golden and Invermere. Smaller storm slabs were also reported in the Dogtooth area.
Looking forward, we can expect to see more large persistent slab avalanches as temperatures spike on Wednesday.
Snowpack Summary
Surfaces are becoming moist on all aspects as the freezing level climbs. Below lies a complex snowpack with several weak layers which are currently concerns for triggering persistent slab avalanches:
An interface from early March, 30 to 50 cm deep, consists of a crust on sunny slopes and lower elevations, and surface hoar or facets in sheltered, shaded upper elevations.
Persistent weak layers from February and January, including crusts, facets, and surface hoar, are buried 50 to 100 cm deep and remain a concern.
The bottom of the snowpack is composed of large facets, which are showing signs of becoming reactive again, with some very large avalanches recently failing on this layer.
Weather Summary
Tuesday night
Partly cloudy. 20 to 30 km/h southwest ridgetop winds. Treeline temperature +3 °C. Freezing level 2500 m.
Wednesday
Mostly sunny. 10 to 20 km/h southeast ridgetop winds. Treeline temperature +5 °C. Freezing level rising to 3000 m.
Thursday
Mostly cloudy with scattered flurries. 20 to 30 km/h southwest ridgetop winds. Treeline temperature 0 °C. Freezing level falling to 2000 m.
Friday
Mostly cloudy with scattered flurries. 10 to 20 km/h southeast ridgetop winds. Treeline temperature -2 °C. Freezing level 1000 to 2000 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- The likelihood of deep persistent slab avalanches will increase with each day of warm weather.
- Cornice failures could trigger large and destructive avalanches.
- Avoid exposure to overhead avalanche terrain; avalanches may run surprisingly far.
- Only the most simple non-avalanche terrain with no overhead hazard is appropriate at this time.
Avalanche Problems
Persistent Slabs
Several buried weak layers exist throughout the snowpack. These layers will likely become increasingly active as the snowpack warms and weakens on Wednesday.
Aspects: North, North East, East, West, North West.
Elevations: All elevations.
Likelihood: Very Likely
Expected Size: 2 - 3
Deep Persistent Slabs
There is evidence that weak layers near the bottom of the snowpack are starting to wake up. Avalanches on these layers will be large, destructive and may run full path.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible - Likely
Expected Size: 2.5 - 4
Loose Wet
Loose wet avalanches will become increasingly likely with rising temperatures, especially at elevations where surface snow is seeing above-zero temperatures for the first time.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Very Likely
Expected Size: 1 - 2