Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Little Yoho, Sunshine, West Side 93N.
It's all about the wind right now, or lack of it. The past week has been almost calm, and the surface snow is deep and fluffy. This will change when the wind begins to blow: windslabs will form and the danger will rise. Watch closely for this tipping point, but until then enjoy the good conditions and avoid steep NE-NW facing alpine slopes.
Confidence
Moderate
Avalanche Summary
Besides some minor sluffing in the new snow, only one size 1.5-deep persistent slab avalanche, triggered by an explosive, was reported at the LL ski area on Monday. On Saturday (>48 hrs ago), a skier went for a ride in a deep persistent slab avalanche at Bow Summit: size 2, ~50m wide x ~150m long, failed on the Oct crust (ground). This was previously reported as a size 1 but has been upgraded.
Snowpack Summary
10-20 cm of low-density storm snow sits over an early-season snowpack ranging from 50-90 cm deep at treeline. Two weak layers exist: a Nov 9 crust layer 25-40 cm above the ground, and an Oct crust just above the ground with facets and depth hoar developing around the Oct crust. We have limited observations of how widespread this Oct layer is, but it seems to be most prominent at treeline and above on northerly aspects.
Weather Summary
The cool and calm weather should continue for another day, as we are under the influence of a NW flow that brings cold temps, light flurries and mostly light winds. The lack of wind has been the dominant feature of the weather over the past week and we keep expecting it to change, but it hasn't yet. Tuesday will range from -5 to -15 with treeline winds light from the NW an no new snow.
Terrain and Travel Advice
- Be aware of the possibility for full depth avalanches due to deeply buried weak layers.
- Pay attention to the wind; once it starts to blow, sensitive wind slabs are likely to form.
- Be careful with sluffing in steep terrain, especially above cliffs and terrain traps.
Avalanche Problems
Deep Persistent Slabs
The Oct 23 crust/facet layer just above the ground, has a 50-80 cm slab above it that has been reactive all week, always on NW through NE aspects in 30-45 degree alpine terrain. We are uncertain as to how widespread the problem but treat steep open alpine features with extra caution.
Aspects: North, North East, East, West, North West.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 1 - 2.5