Avalanche Forecast
Regions: Banff Yoho Kootenay.
A continued cautious approach to terrain is a good idea. We still have lots of uncertainty about how the snowpack will react in steep terrain due to the deep weak layers in the snowpack. Be patient!
Weather Forecast
Temperatures will start to gradually cool on Tuesday though valley bottoms may reach the freezing mark. Winds will drop into the light to moderate range out of the West and a few flurries are expected to start in the afternoon. Wednesday and Thursday continue to cool and will see flurries continue through the day.
Snowpack Summary
Warming temperatures and moderate to strong Southerly winds continue to build wind slabs in the alpine and at ridge tops at tree line. There is 40-60 cm above the Dec 31 layer of facets, surface hoar and sun crust which is slowly becoming less reactive. Concern remains for the weak layers of facets and depth hoar near the base of the snowpack.
Avalanche Summary
A few new natural avalanches observed on Monday up to size 2.5 from wind loading including one cornice failure on Crowfoot Peak. On Sunday a skier triggered a size 2.5, 200 m wide on Lipalian Mountain (near Lake Louise). The slab stepped down through multiple layers eventually releasing on the basal facets.
Confidence
Avalanche Problems
Wind Slabs
Cornice failures and wind slabs triggered by wind loading continue to be reported in the area. Minimize exposure to cornices and avoid steep wind loaded terrain until things settle out.
- If triggered the wind slabs may step down to deeper layers resulting in large avalanches.
- Use caution in lee areas. Recent wind loading has created wind slabs.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 2.5
Persistent Slabs
The late Dec layer of surface hoar, facets or sun crust is buried 40-60cm throughout the region and producing variable results depending on location and what crystal form is present. There is still high uncertainty as to how reactive this layer is.
- If triggered the persistent slab may step down to deeper layers resulting in large avalanches.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood: Possible - Likely
Expected Size: 1 - 2.5
Deep Persistent Slabs
We have seen a few recent avalanches on the deep persistent problem of basal facets and depth hoar, often beginning as wind slabs and then stepping down to the weak base. Conservative terrain choice is your best defence.
- Avoid shallow snowpack areas where triggering is more likely.
- Pay attention to overhead hazards like cornices which could trigger the deep persistent slab.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible - Likely
Expected Size: 2 - 3.5