Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Regions
Banff Yoho Kootenay.
High freezing levels combined with a weak mid-pack this means there is a lot of uncertainty in our snow pack over the weekend. Choose conservative route options until things improve.
Weather Forecast
Rising freezing levels (up to 2100m) with moderate West winds and small amounts of precipitation are forecast for Saturday and Sunday.
Snowpack Summary
15-20cm of snow over the past week at treeline. New sun crusts forming on solar aspects and moist snow at lower elevations. SW winds forming small wind slabs near ridge crests and in high alpine areas. In the main ranges a firm upper snow pack covers a weak mid-pack of facets and depth hoar which sits on a denser layer of facets near the ground.
Avalanche Summary
Some solar triggered sluffing out of steep rocky terrain and small cornice failures were observed in the Banff region on Friday. Several natural and skier triggered slabs on the weak mid pack facets have also occurred in the past several days in both Kananaskis Country and the Banff region showing the potential for avalanches on this weak layer.
Confidence
Freezing levels are uncertain on Saturday
Problems
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.