Regions
Banff Yoho Kootenay.
Touchy windslabs continuing to build. Another 25 cm with gusty SW winds expected before storm ends mid-day Friday. For climbing, it's a good time to stay clear of avalanche terrain and skiers should avoid open windloaded slopes and overhead hazard.
Weather Forecast
Another 25 cm is forecasted for the region tonight and ending mid-day Friday. Winds will be SW light - moderate SW with gusts to 60 km/hr. On the heels of the snow ending, the temperatures will plummet to -30 for Saturday & Sunday with highs of -20C. Monday temperatures start to warm slightly.
Snowpack Summary
There is approximately 30 cm of storm snow (more at higher elevations closer to the divide). The new snow is not bonding well to the underlying weak faceted midpack that blankets the region. At the base is the early November rain crust, which also poses a step down concern.
Avalanche Summary
Avalanches to size 2 were observed today in lee terrain in the alpine. Avalanches were failing at the storm snow interface and some stepped down to the Nov 6 rain crust (40-50 deep).
Confidence
Intensity of incoming weather systems is uncertain
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.