Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Sunshine, West Side 93N.
A major avalanche cycle occurred in the forecast region Tuesday afternoon with slides up to size 3.5. Conditions will be ripe for human triggering on Wednesday.
Confidence
Moderate
Avalanche Summary
A cycle up to size 3.5 peaked Tuesday afternoon. Most major avalanche paths ran full path in the Banff area. Included are Cascade Waterfall, Urshole Gully, Professors, and Bourgeau Left. Lake Louise patrol also reported a widespread cycle in the immediate backcountry with deep slabs observed in Purple Bowl and Redoubt Bowl size 2.5.
Snowpack Summary
Up to 40cm of storm snow in the alpine (end of day Tuesday) overlies previous windslabs and suncrusts with rain-saturated snow below 1800m. Storm slabs can still 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
Diminishing wind into the light range is expected on Wednesday. There is a possibility of localized convective flurries, with amounts potentially up to 10cm. Valley temps should be slightly above zero, with alpine temps holding steady around -10.
Avalanche Problems
Storm Slabs
Up to 40cm of storm snow has fallen and has created widespread storm slabs in alpine and tree-line areas. The storm snow will need several days to settle and bond. In the alpine, wind will have contributed to making the storm slabs even thicker.
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