Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Little Yoho, Sunshine, West Side 93N.
Warm temps should make travel more pleasant but we are still dealing with a thin early season snowpack. The generally weak faceted snowpack means that even small avalanches could run further than expected as they entrain facets in steep terrain. The deep persistent layer remains a concern on large alpine slopes.
Confidence
Moderate
Avalanche Summary
Several small wind slabs were reported on lee slopes in the alpine over the weekend.
In the past week a few natural and explosive-triggered avalanches up to size 2 have been reported on the Oct deep persistent layer on north aspects in the alpine.
Sunday a couple size 1-1.5 explosive triggered slides were reported at Sunshine on the Nov crust on south aspects in the alpine.
These avalanches have been entraining facets and sometimes running further than expected as a result.
Snowpack Summary
In general, we are still dealing with an early-season snowpack, measuring 50-90 cm at treeline. Previous strong winds have created a heavily wind-affected upper snowpack in the alpine. A Nov crust is present mid-pack on south aspects. The main layer of concern remains the October crust near the ground on north aspects, where facets and depth hoar are developing. Overall, the snowpack is losing its support and cohesion due to facet development.
Weather Summary
Monday will see a clearing trend with moderate to strong winds out of the west. The gradual warmup will persist into the start of the week, with daytime highs reaching -3°C in the alpine by Tuesday.
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
Moderate to strong west winds are forecast to persist through Tuesday. Wind slabs are expected on immediate lee slopes in the alpine. If these wind slabs fail they may also entrain the facets in the snowpack and run further than expected.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood: Possible
Expected Size: 1 - 1.5