Avalanche Forecast
Regions: Glacier.
A weak layer is present at the ideal depth for large rider triggered avalanches.
The safest way to manage this problem is through conservative terrain choices.
Confidence
Moderate
Avalanche Summary
No new natural avalanches were observed along the highway corridor.
On Tuesday, a group triggered a size 2.5 on Ursus Minor. This avalanche was triggered in a wind loaded pocket near ridge top, in a generally shallow faceted snowpack. Wide, impressive propagation occurred on the Dec 1 surface hoar, facet layer.
Snowpack Summary
Storm snow buries a new surface hoar layer, which sits on top a thin sun crust in steep terrain.
A rain crust down 40cm is present up to 2100m.
A weak layer (Dec 1 surface hoar) buried 70-100cm deep continues to produce 'sudden' results in snowpack tests and human triggered avalanches. The surface hoar sits on a sun crust on solar aspects at upper elevations.
The base of the snowpack is facetted at upper elevations.
Weather Summary
Friday: Trace precip, moderate SW winds, High: -3 °C, Freezing level 1500m.
Saturday: Cloudy, sunny periods, High: -3 °C, Moderate SW winds, freezing level 1400m.
Sunday: Cloudy, sunny periods, High: -1°C, light SW winds, freezing level 1700m.
Terrain and Travel Advice
- Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
- Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
Avalanche Problems
Storm Slabs
Expect fresh storm slabs building Thursday into Friday. Watch for reactive slabs on lee features in the alpine and at treeline. This problem may be more likely to trigger in sheltered areas where surface hoar is present beneath the slab.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 2
Persistent Slabs
A weak layer of surface hoar is down 70-100 cm. This is a prime depth for rider triggering. To manage this problem, stick to conservative terrain. Below 2100m this layer is bridged by a supportive rain crust.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1.5 - 3