Regions
Banff Yoho Kootenay.
Human triggered avalanches are likely on the Oct .26 basal facets/depth hoar. Watch for wind loading Friday as this could trigger large natural avalanches.
Weather Forecast
Warmer temperatures for the next couple of days (still below freezing) and no significant snow in the forecast. SW winds may increase Thursday in the alpine which is something to look out for.
Snowpack Summary
Up to 70 cm of snow of recent snow with variable wind effect has put a dense load over the persistent weak layers. In thicker snow pack areas, the Dec. 10th weak layer of facets is now down 100-150cm with a stronger snowpack below. In thin snowpack areas, the Dec.10th layer is mixed in with the October 26 basal facets and crust.
Avalanche Summary
We keep getting reports of large avalanches happening in various locations. Today we had a report of numerous size 2 - 3.5 avalanches initiating naturally in the Cirque Peak and Jimmy Simpson area along Highway 93N. They were reported to step down to the basal facets, and a localized increase in wind was the likely trigger.
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.