Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Sunshine, West Side 93N.
Start and finish early to take advantage of better travel and a lower likelihood of upper snowpack avalanches while the surface snow remains frozen. Also, keep the deep persistent slab in mind as this remains a concern and can be triggered regardless of surface snow conditions.
Confidence
Moderate
Avalanche Summary
Some small loose wet avalanches have been observed in the past few days on steep solar aspects or at low elevations with daytime warming. A size 3 skier-triggered avalanche failing on the basal facets occurred in a closed area within the Lake Louise ski resort on Saturday.
Snowpack Summary
1-4 cm new snow. Solar aspects are getting moist in the afternoon, creating new crusts daily, and multiple buried crusts are present. On northerly aspects, temperature crusts are present up to 2200 m, with 10-20 cm of preserved surface snow above this elevation and some wind transport at ridge crests. The base of the snowpack remains weak due to the presence of facets and depth hoar.
Weather Summary
Some clearing tonight, followed by building clouds and flurries or rain below 2100 m on Wednesday. Winds will increase to WSW strong. Afternoon freezing levels will climb further to 23-2500 m. Freezing levels will fall to the valley bottom at night.
Thursday, skies clear, winds diminish, and solar input becomes more of a factor.
Towards the weekend, temperatures climb with strong solar input and little to no overnight recovery.
Terrain and Travel Advice
- A moist or wet snow surface, pinwheeling and natural avalanches are all indicators of a weakening snowpack.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
Avalanche Problems
Deep Persistent Slabs
The weak basal facets and mid-pack facets/crusts will remain a concern for the foreseeable future. Daytime heating may also increase the likelihood of triggering this weakness. Stick to well supported lower angle terrain to avoid this problem.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 2 - 3
Storm Slabs
Watch for new snow instabilites especially in places where convective weather cells have deposited more snow. Areas with new snow over a crust, recently wind loaded slopes, or places where the surface snow is becoming moist are the main concerns.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 2
Loose Wet
With rising daytime freezing levels, expect moist snow at lower elevations with the potential for wet loose avalanches to occur. Any sunny breaks will also contribute to this problem on steep solar aspects up into the alpine.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible - Likely
Expected Size: 1 - 1.5