Regions
Banff Yoho Kootenay.
Human triggering is going to be a problem this weekend. Avoid exposure to avalanche terrain.
Weather Forecast
Continued flurries, moderate winds, and moderately cool temperatures are unlikely to do much to reduce the deep instabilities in the area.
Snowpack Summary
50-60cm of storm snow over the past week has been surprisingly reactive. Winds will continue to move the new snow onto lee (east) slopes. The weak faceted base released in many avalanches over the past week as smaller avalanches stepped down, or a tipping point was reached in slab weight.
Avalanche Summary
Large avalanches have been running this week naturally, or with explosives along the highway. Some of the failures have been associated with less steep areas and these slides have been running surprisingly far. It is expected that the natural activity will be reduced but human triggered avalanches will continue to be touchy and likely.
Problems
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.
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.