Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Little Yoho, Sunshine, West Side 93N.
The snowpack remains untrustworthy and highly unstable, with human-triggered avalanches likely. After a week of widespread natural avalanches, the potential for more natural activity lingers. This is a time for strict terrain discipline.
Confidence
High
Avalanche Summary
Avalanche accident Friday, outside of Lake Louise Ski Area Boundary. A size 2.5 avalanche was triggered and failed on the deep persistent layer at the ground. Today, Lake Louise patrol reported a size 1.5 deep persistent slab below treeline. Sunshine patrol reported triggering a reloaded alpine feature with explosives, size 2.5.
Snowpack Summary
A few cm of new snow overnight by Sun morning. Since Mar 8, 40 to 70 cm of settled storm snow has accumulated, with the deepest amounts found in the Bow Summit area, along the Wapta, and Little Yoho. As time goes on, the storm snow will settle into slabs.
A persistent weak layer (Feb 22/Jan 30 facets) is buried 50-100 cm. In shallower eastern areas, the mid/lower snowpack is very weak with facets and depth hoar, while deeper western areas are more consolidated. Takakkaw Profile.
Weather Summary
Slightly cooler than seasonal temperatures, with valley lows just below zero and ridge-top temperatures as cold as -15°C. Expect convective flurries and intermittent snow showers on Monday, with minimal accumulation. Winds will be moderate from the west.
Terrain and Travel Advice
- Make conservative terrain choices and avoid overhead hazard.
- Remote triggering is a big concern, be aware of the potential for wide propagations and large, destructive avalanches at all elevations.
Avalanche Problems
Persistent Slabs
In many areas, the storm snow has overloaded the persistent layers in the mid and lower snowpack. Natural activity has continued through the week. Human remote-triggering has been observed several times and will likely continue.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely - Very Likely
Expected Size: 2 - 3.5
Storm Slabs
Since March 8, 30-90 cm of storm snow and strong southerly winds have created storm and wind slabs at all elevations. More snow fell in the northern forecast area (Bow Summit). Settlement of the surface snow means a stiffer slab is forming, potentially allowing wider propagations.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely
Expected Size: 1.5 - 2.5