Avalanche Forecast
Regions: Banff Yoho Kootenay.
15-25 cm of recent light snow is not bonding well to the underlying snow. Choose lower angle terrain for riding and carefully select climbs to manage the new problems.
Weather Forecast
As the Arctic air slides into the region for a short visit, temperatures will noticeably drop in the afternoon as the winds shift to light from the North. The coldest day will be Wednesday where morning temps will be in the -25 range with sunny skies and then warm through the day and into Thursday.
Snowpack Summary
15-25 cm in the last 24 hrs has created fresh windslabs & surface instabilities that are bonding poorly to the underlying surface of surface hoar/crusts/facets. Expect easy triggering of these soft slabs. It's unlikely to wake up the deep facets, but they continue to lurk 60-100 cm deep and could be triggered by cornice failures should they occur.
Avalanche Summary
New wind slabs were ski & explosive triggered in the immediate lees by the ski hill snow safety teams. In Yoho, numerous storm slabs observed/triggered in steep terrain. Over the past week there have been a few avalanche to sizes 3 on the persistent weak layer. All were triggered by large loads (cornice).
Confidence
Avalanche Problems
Wind Slabs
New windslabs have formed in the immediate lees of features and are up to 40 cm deep. This is different from the windslabs described in previous days.
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
Aspects: North, North East, East, South East, South.
Elevations: Alpine.
Likelihood: Likely
Expected Size: 1 - 2
Storm Slabs
There is a touchy storm snow interface, down 15-35 cm, on surface hoar/crust/facets buried on Jan 30. Steep rolls with >20 cm of snow are most reactive, if they have not already slid.
- Convex features and steep unsupported slopes will be most prone to triggering.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood: Very Likely
Expected Size: 1 - 1.5
Persistent Slabs
This problem represents both the Dec. 2nd crust/ facet layer (treeline and below) and the late December facet layer. Lots of variation in the sensitivity ranging from reactive sudden collapse to no results depending on location, aspect and elevation.
- If triggered the wind slabs may step down to deeper layers resulting in large avalanches.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Unlikely - Possible
Expected Size: 2 - 3