Regions
Banff Yoho Kootenay.
A weak snowpack structure inspires very little confidence. Carefully consider your route and manage your group to minimize the potential for triggering.
Weather Forecast
Following warm temperatures and crust formation to treeline on solar aspects Friday, a cold front that will pass overnight will bring cooling, clouds, and up to 5cm of snow. While daytime freezing levels may approach 2000m Saturday, continued cooling, cloud and a bit of snow can be expected into Sunday as a second cold front reaches the divide.
Snowpack Summary
Treeline height of snowpack average values range from 100 to 170cm. The Feb 11 layer is of crust and isolated surface hoar is down 30 to 50cm. The Jan 6 layer of Facet Crystals is the dominant snowpack feature and is down about 50cm. This layer is producing whumpfing, cracking and has been responsible for much of the recent avalanche activity.
Avalanche Summary
Limited amounts of wet loose snow avalanches were observed today in sheltered alpine bowls as well as treeline and below on solar aspects. On Wednesday a large slab was triggered by a cornice up high on the Wapta. On Tuesday a small sluff ran over the French Reality Ice Climb in Kootenay and triggered a 100 cm deep slab on the slope below.
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.