Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Little Yoho, Sunshine, West Side 93N.
With winds increasing and new snow on the way, the avalanche hazard is expected to rise by Wednesday.
Recent avalanche reports highlight that the deep persistent problem remains the primary concern; see the avalanche summary for more details.
Confidence
No Rating
Avalanche Summary
On Sunday, we received two separate reports (report 1 / report 2) of large, human-triggered avalanches in the Highway 93N backcountry. Both avalanches failed on the deep persistent avalanche problem. Although recent natural avalanche activity on this layer has been minimal, these reports indicate that it remains active and continues to be the primary concern in the snowpack.
Snowpack Summary
Recent winds have created small wind-slabs in alpine lees. The mid and lower pack is faceted and weak east of the divide, and more settled in western regions. Weak interfaces exist down 20-40 on a facets/suncrust layer, and near the ground on the deep persistent layer (Nov 9 and Oct 20 interfaces). Snowpack depths at tree-line is about 60 cm in eastern areas and 100 cm west of the divide.
Weather Summary
Tuesday: Isolated flurries in the morning, with 2-4 cm of snow accumulation expected throughout the day. Freezing levels will remain at the valley bottom. Ridge winds will increase gradually, reaching moderate to strong values.
Wednesday: Snow intensifying early in the morning, with 10 to 20 cm expected throughout the day. Winds will peak midday, with strong to extreme values from the southwest.
Terrain and Travel Advice
- Avoid thin areas like rocky outcrops where you're most likely to trigger avalanches on deep weak layers.
- Watch for newly formed and reactive wind slabs as you transition into wind-affected terrain.
Avalanche Problems
Deep Persistent Slabs
Two weak layers near the base of the snowpack (Oct 20 and Nov 9) are producing slab avalanches down about 60-100 cm. Any areas with a stiffer slab over the mid pack facets have the potential to step down to these layers. Areas of most concern are steep, thin, wind affected spots.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Unlikely - Possible
Expected Size: 1.5 - 2.5
Wind Slabs
Previous SW/W winds have created small wind slabs in lee features of the alpine. Pay attention to wind loading as you transition to alpine terrain.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood: Unlikely - Possible
Expected Size: 1 - 1.5