Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Little Yoho, Sunshine, West Side 93N.
“Mt. Whymper avalanche closure zone is CLOSED on Tuesday, February, 27th. Recent loading from 35-55 cm of new snow and strong winds, and avalanche activity has the hazard elevated.
Natural avalanche activity should taper on Tuesday, but conditions will remain RIPE for human triggering.
Confidence
Moderate
Avalanche Summary
There have been plenty of reports over the past 24 hours of natural and skier and climber-triggered avalanches to size 3. This includes a partial burial of 2 people on Mt. Whymper's North side, Corral Creek 3, and today around the corner from Corral 3. Several avalanches are failing on the Feb 3 crust down 50-60 cm and some step down to weaker layers.
Snowpack Summary
35-55 cm of storm snow since Feb 21. The new snow and strong SW winds have formed widespread slabs at treeline and above, and storm slabs below treeline. 30-70 cm+ overlies the Feb 3 crust and facets, which is 0.5-15cm thick and exists up to 2500m (higher on solar aspects). In shallower snowpack areas, weak facet layers can be found in the mid and lower snowpack.
Weather Summary
Tuesday- trace amounts are forecasted with light winds increasing to moderate SW late in the day as another system moves into the region Tuesday night. Temperatures rise to -18C.
Wednesday - 5-10 cm with strong SW wind, highs of -6C
Thursday - generally 5-10 cm forecasted, but could be 15-20 cm in some locations with strong SW wind. Temperatures rise to around -7C at treeline
For more information, see AvCan's Mt Wx.
Terrain and Travel Advice
- Avoid lee and cross-loaded terrain.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Avalanche Problems
Storm Slabs
Touchy storm slabs exist in alpine and treeline terrain, and possibly below treeline. These slabs generally overlie faceted snow and/or a crust, and are primed for triggering. Numerous natural & ski-cut avalanches have occurred in the last 24 hours on this interface, some have stepped to ground.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Very Likely
Expected Size: 1 - 3
Deep Persistent Slabs
Recent avalanches or cornice failures have stepped down to the weak mid-pack or basal facet layers. It's problematic in thin snowpacks, rocky, and steep locations. and less problematic in thicker snowpacks with a dense mid-pack. Generally, recent loading has made this layer more sensitive.
Aspects: All aspects.
Elevations: Alpine.
Likelihood: Possible
Expected Size: 1.5 - 3
Loose Dry
Although the winds have tapered, with 35-55 cm of recent snow, if the sun pops out or if there is an occasional gust of wind on Tuesday, it may trigger some loose dry activity.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 1.5