Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Little Yoho, Sunshine, West Side 93N.
Winds are expected to increase on Monday. Stay alert for increases in localized wind slab development and snow transport, as well as potential for failures on the Oct crust/facet layer.
Recent snowfall has improved skiing conditions at higher elevations, though it's important to remain cautious of rocks and hidden hazards.
Confidence
Moderate
Avalanche Summary
Ski hills reported several size 1-2 avalanches triggered by explosives including loose dry slides and a few slabs on the Oct crust/facet layer near the ground. These slabs were on northerly aspects above 2400 m like other recent results.
One skier accidental on the Oct crust/facets was reported at Bow Summit.
A couple of natural size 2 cornice triggered slabs were observed in steep alpine terrain on Mt Brett and Monarch and both appeared to fail on the Oct crust/facet layer.
Snowpack Summary
10-20 cm of low-density storm snow with some wind effect developing, 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
Scattered flurries with minimal snow accumulation are expected to continue across the forecast region. Ridge-top winds will increase on Monday into the moderate range from the west. Temperatures will stay cool with treeline highs around -12 to -14°C.
This pattern is expected to last through Tuesday, with cooling temps and a little bit of snow on Wednesday.
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 been reactive in the past week with the most alarming results in the Sunshine area, and fewer reports in other regions. We are uncertain as to how widespread the problem but treat steep open alpine features with extra caution.
Aspects: North, North East, East, North West.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 1 - 2.5
Wind Slabs
Increasing wind from the west on Monday may start moving the recent surface snow around. If this occurs, watch for the development of new wind slabs in lee areas of the alpine, and sluffing in steep gullies, couloirs or confined ice climbs.
Aspects: North, North East, East, South East.
Elevations: Alpine.
Likelihood: Possible
Expected Size: 1 - 2