Avalanche Forecast
Regions: Purcells.
Recent snow created widespread storm slabs which are likely to remain surprisingly touchy where they sit on surface hoar. Extra caution is recommended where the snow is wind affected, where it sits on a (sun) crust, or shady polar slopes especially near treeline.
Confidence
High - We have a good understanding of the snowpack structure and confidence in the weather forecast Uncertainty is due to extremely variable snowpack conditions reported through the region.
Weather Forecast
MONDAY NIGHT: Clear periods with light flurries possible. Temperatures -10 to -15 C. Light wind.
TUESDAY: Mix of sun and cloud with trace to a few cm of snow. Temperatures -5 to -10 C. Light southwest or west wind.
WEDNESDAY: Mix of sun and cloud with trace to a few cm of snow. Temperatures -5 to -10 C. Light to moderate gusty west wind. Freezing level rising to around 1500 m in the afternoon.
THURSDAY: Similar to Wednesday with light to moderate west wind.Â
Avalanche Summary
Storm snow was touchy over the weekend with small (10 to 30 cm deep) natural and human triggered soft Storm Slab and Loose Dry avalanches.
A few sporadic large avalanches were reported over the past 10 days. Most recently, a large (size 3) deep persistent slab avalanche was remotely triggered last Sunday just outside the forecast region near Mt. Seven. Photos in the Mountain Information Network report show this avalanche was initiated by a skier causing a whumpf on a ridge that released a small wind slab on an east-facing alpine slope which then stepped down to the facets at the bottom of the snowpack.Â
Snowpack Summary
Around 20 to 30 cm of recent snow covers a widespread layer of surface hoar (size 5-15 mm.) at all elevations. On southeast through southwest facing slopes this surface hoar likely grew on a thin sun crust which is almost a perfectly nasty combination. The middle of the snowpack is strong; however, the base of the snowpack contains basal facets which are responsible for occasional and hard-to-predict large Deep Persistent Slab avalanches in shallow rocky start zones.Â
Terrain and Travel
- Be alert to conditions that change with elevation and wind exposure.
- Shooting cracks, whumphs and recent avalanches are strong indicators of an unstable snowpack.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Avalanche Problems
Storm Slabs
10 to 30 cm of recent snow is sitting on top of a widespread layer of surface hoar at all elevations. On solar aspects the surface hoar is sitting on a crust, a particularly nasty combination.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely
Expected Size: 1 - 2
Deep Persistent Slabs
Weak snow at the bottom of the snowpack continues to pose a deep persistent slab avalanche problem. The most recent activity has been focused around the Golden area, but wind scoured, rocky, shallow terrain (often with a "salt & pepper look) throughout the region can be suspect. Avoid big alpine slopes that are threatened by cornices overhead.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Unlikely
Expected Size: 2 - 3.5