Avalanche Forecast
Cold snow exists on high northerly slopes but this is also where persistent weak layers are most likely to be triggered.
Use low-angle terrain and avoid overhead hazard to avoid this problem.
Confidence
Moderate
Avalanche Summary
Where a thick, supportive surface crust is found, we expect that triggering avalanches on buried weak layers is unlikely.
A natural avalanche cycle occurred last weekend, with very large slab avalanches (to size 4) failing on buried persistent weak layers. On Sunday, skiers remotely triggered a size 3 persistent slab near Shames (see photo). Reports of large avalanches to size 3 continued Tuesday through Thursday, likely triggered by warm temperatures or solar input.
Snowpack Summary
A melt-freeze crust has formed on most surfaces. Dry snow persists on northerly aspects at upper elevations.
Three persistent weak layers remain notable in the snowpack and have been responsible for recent large avalanches. Surface hoar that formed in mid-March can be found 50 to 100 cm below the snow surface. Below this, another layer of surface hoar that formed in early March can be found at a depth of 100 to 150 cm. Additionally, a layer of facets, surface hoar, and/or a crust from mid-February is buried 100 to 200 cm deep.
Weather Summary
Saturday Night
Partly cloudy. 30 km/h south ridgetop wind. Treeline temperature -9 °C.
Sunday
Partly cloudy. 30 km/h southeast ridgetop wind. Treeline temperature 0 °C. Freezing level rises to 1500 m.
Monday
Mostly sunny. 20 to 30 km/h south ridgetop wind. Treeline temperature 0 °C. Freezing level 1500 m.
Tuesday
Increasing cloud with a few flurries. 20 to 40 km/h southwest ridgetop wind. Treeline temperature -2 °C. Freezing level drops to 1000 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be aware of the potential for large avalanches due to buried weak layers.
- Make conservative terrain choices and avoid overhead hazard.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
- Back off slopes as the surface becomes moist or wet with rising temperatures.
Avalanche Problems
Persistent Slabs
Surface hoar and facets in the upper snowpack have recently produced large avalanches. These layers are mostly likely to be reactive at upper elevations where no surface crust has formed.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 2 - 3.5
Wind Slabs
Strong winds have redistributed any available loose snow. Check for windslabs in lee or cross-loaded features.
Aspects: North, North East, South, South West, West, North West.
Elevations: Alpine.
Likelihood: Possible
Expected Size: 1 - 2
Loose Wet
As temperatures rise, the surface snow may become moist and unstable on solar slopes, producing small loose wet avalanches.
Aspects: All aspects.
Elevations: Below Treeline.
Likelihood: Possible
Expected Size: 1 - 1.5