Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Little Yoho, Sunshine, West Side 93N.
Elevated winds and a weak faceted snowpack may increase loose dry avalanche activity in steep terrain.
The deep persistent layer remains a major concern on large alpine slopes
Confidence
Moderate
Avalanche Summary
On Saturday, we received several reports of reactive wind slabs forming on immediate lee slopes in the alpine. These small avalanches have been entraining the heavily faceted snowpack in steep terrain.
Over the past week, we've observed several avalanches, both natural and explosive-triggered, reaching up to size 2 on the deep persistent layer. The common factor among these avalanches has been their occurrence on north aspects in the alpine.
Snowpack Summary
In general, we are still dealing with an early-season snowpack, measuring 50-90 cm at treeline. Strong to extreme winds have created a heavily wind-affected upper snowpack in the alpine. The main layer of concern remains the October crust near the ground, where facets and depth hoar are developing. Overall, the snowpack is losing its support and cohesion due to facet development.
Weather Summary
A gradual warmup will persist into the start of the week, with daytime highs reaching -3°C in the alpine by Tuesday. Flurries Sunday will only amount to a trace of snow accumulation. Strong alpine winds are expected to continue Sunday.
Terrain and Travel Advice
- Be aware of the possibility for full depth avalanches due to deeply buried weak layers.
- Avoid freshly wind-loaded terrain features.
Avalanche Problems
Deep Persistent Slabs
The crust/facet layer from October 23, located just above the ground, is capped by a 50-80 cm slab. This layer has caused avalanches over the past week. The extent of the problem remains uncertain, but we advise exercising extra caution on steep, open alpine features.
Aspects: North, North East, East, West, North West.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1.5 - 2.5
Wind Slabs
Strong winds are forecasted to persist through Tuesday, with new slab development expected on immediate lee slopes in the alpine.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood: Possible
Expected Size: 1 - 1.5
Loose Dry
With elevated winds through to Monday and a heavily faceted upper snowpack, we can expect some wind generated loose dry avalanche activity in steep alpine terrain.
Aspects: All aspects.
Elevations: Alpine.
Likelihood: Possible
Expected Size: 1 - 1.5