Regions
Banff Yoho Kootenay.
Avalanche control is planned for Mt. Bourgeau and the Vermillion Crossing slide paths. If all the red on the bulletin isn't enough, here is another reason to not go into avalanche terrain tomorrow!
Weather Forecast
Warm temperatures and clear skies will dominate for the next few days as the surface high moves over us. Winds will be lighter, but still gusty. With freezing levels rising to 1800 m on Thursday and Friday and possibly over 2000 m on Saturday, the big factor to watch for is the warm temperatures, especially on solar aspects.
Snowpack Summary
Strong winds have created widespread windslabs on lee aspects (N-SE) and stripped all the snow off windward aspects. The new snow and wind loading has overloaded the basal weakness and is responsible for the widespread natural avalanche cycle we have been seeing. Although natural activity is tapering, conditions remain prime for human triggering
Avalanche Summary
Avalanche control today on Mt Dennis produced large avalanches up to size 3.5 in areas that had not been previously controlled this season. Additionally, numerous large natural avalanches observed in Kootenay Park and the Lake Louise Backcountry in the last 24h running to the end of historical runouts.
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.
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.