Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.
Regions
Banff Yoho Kootenay.
Watch for areas where a cohesive slab may exist over the weak, faceted crystals associated with the October 26 crust near the base of the snowpack.
Weather Forecast
The flow switched back to the west today with light to moderate W or SW winds at the high stations. Temps will remain near -5C at 2000m Sunday but start to climb reaching 0C by Tuesday as a low pressure system approaches from the coast. Precip is possible Sunday and Monday but will intensify for Tuesday as the low reaches the region.
Snowpack Summary
5cm to 10cm of new snow now buries surface hoar, crust on steep south slopes and previous wind effect. With 40 to 85cm at 2200m across the region, the entire snowpack is weakening as it facets. The October 26 crust generally is found 10 to 30 cm above the ground. As this crust breaks down, large facets are growing both above and below it.
Avalanche Summary
Skiers at Harvey Pass near Sunshine Village yesterday remote triggered a slab at about 2500m on a NE aspect while the avalanche control team at Lake Louise triggered a slab on Whitehorn on a similar aspect and elevation. Both of these slabs failed on the October 26 deep persistent layer approx 50 cm deep and were size 1.5- 2.
Confidence
Due to the number of field observations
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.