Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Sunshine, West Side 93N.
A significant storm on Monday/Tuesday will have added additional load to the snowpack (snow above 2000m and rain below). It will take some time for the snowpack to adjust to this load. Conservative terrain choices are in order.
Confidence
Moderate
Avalanche Summary
Road patrol to Kootenay Park showed numerous loose wet avalanches (below 1900m) up to size 2 running to middle of the runouts. Ski hills reported ski-cutting storm snow avalanches out of steeper terrain.
Snowpack Summary
Up to 20 cm of storm snow in the alpine (end of day Monday) overlies previous windslabs and suncrusts with rain saturated snow below 1800m. Storm slabs can be expected in the alpine and tree-line areas.
Several buried crusts can be found in the top 50-60 cm on solar aspects. The bottom of the snowpack remains facetted and weak.
Weather Summary
Monday Night: Freezing levels will reach valley bottoms. 5-10 cm of snow expected above tree-line.
Tuesday: Freezing Levels around 14-1600m. 10-15 cm of snow above 2000m. Winds will be 20-40km/h from W/SW.
Wednesday: Cloudy skies with light flurries that will be convective in nature. Freezing Levels 14-1600m.
Avalanche Problems
Storm Slabs
Up to 20 cm of new snow on Monday (and another 25 expected by end of day on Tues) will have created widespread storm slabs in alpine and tree-line areas. The storm snow will need several days to settle and bond.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Likely - Very Likely
Expected Size: 1 - 2.5
Deep Persistent Slabs
The November basal facets (as well as midpack facets on crusts) remain a concern for triggering. The new load (snow above 2000m and rain below) will be a big test for this layer. Caution is advised until the snowpack can adjust to the new load.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely
Expected Size: 2 - 3.5