Regions
Banff Yoho Kootenay.
No recent natural avalanches, but a report of a large rockfall in the popular Puzzle Peak area gives skiers something new to think about! Strong winds and incoming light precip will slowly raise the danger over the next few days
Weather Forecast
A warm wet storm is approaching the coast, but we won't get much in the Rockies. Winds have already picked up to strong to extreme from the south, but will ease as it starts to snow on Tuesday. Expect light snow on Tuesday (2-10 cms) and mild temps. Wednesday should see another 2-5 cms with moderate SW winds
Snowpack Summary
Moderate to strong south winds are creating windslabs in the alpine. These sit over sun crust on steep south slopes or surface hoar on sheltered N aspects. The Oct 26 crust is found ~10-30 cm above the ground with large facets growing both above and below it. The snowpack averages 40-85 cm at 2200m across the region and is weakening as it facets
Avalanche Summary
The October 26 crust and facet layer is still occasionally reactive. One explosive controlled size 2 failing on the Oct 26 crust was reported in the alpine at Lake Louise on Sunday. Ski cutting produced a thin new snow slab on a steep alpine S aspect at Sunshine Village on Sunday. No new natural avalanche activity observed on Monday
Confidence
Intensity of incoming weather systems is uncertain on Wednesday
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.