Avalanche Forecast
Issued: Dec 13th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs, Loose Dry and Storm Slabs.
CB,
Avalanche Canada
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.
Summary
Confidence
Avalanche Summary
Natural avalanches are possible later in the day Thursday with an incoming storm forecast.
On Wednesday, 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 Thursday will start to bury a new surface hoar layer, which sits on top a thin sun crust in steep terrain.
A rain crust down 30cm 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
A weak front sweeps across the province giving light snow and dropping freezing levels on Thursday.
Thursday: Snow 10cm with light SW winds, High: -5 °C, Freezing level 1600m.
Friday: Isolated flurries, High: -2 °C, light SW winds, freezing level 1700m.
Saturday: Cloudy with sunny periods, High: -3°C, light SW winds, freezing level 1500m.
Terrain and Travel Advice
- Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
- Watch for fresh storm slabs building throughout the day.
- Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.
- Early season avalanches at any elevation have the potential to be particularly dangerous due to obstacles that are exposed or just below the surface.
- Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
Problems
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, with a deeper snowpack and slopes that have seen significant skier traffic. Below 2100m this layer is bridged by a supportive rain crust.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Dry
Loose surface snow is easily triggered in steep terrain. Fresh storm snow will increase the size of these avalanches. Use caution, even small sluff can push you into dangerous terrain.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Storm Slabs
Expect fresh storm slabs building on Thursday. 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
Expected Size
Valid until: Dec 14th, 2023 4:00PM
