Regions
Banff Yoho Kootenay.
The weak Oct.26 basal depth hoar and facets are not going to magically go away. Its going to be a long waiting game for good conditions in bigger terrain and we are not there yet. Good ski quality exists in sheltered areas.
Weather Forecast
Inverted temperatures will persist for the next couple days with 3000m temperatures in the -5 to -2C range and valley bottom temperatures much cooler (-10 to -15C). Winds will be light to moderate from the SW Sunday.
Snowpack Summary
Snowfall since Jan2 has been redistributed by southwest winds yielding extensive wind effect in the alpine. In thick snowpack areas, the Dec 10th weak layer of facets is now down 100-150cm with a stronger snowpack below. In thin snowpack areas, there is little separation between Dec 10 and the weak depth hoar/ facets sitting 40 cm above the ground.
Avalanche Summary
Natural activity noted on Fatigue Mountain and Mount Ball up to size 3 today, both deep persistent slides scrubbing to ground. We have had observations like this every day for a week. Explosive control today at ski hills in previously controlled terrain produced minimal results,and reports were that the wind slabs were less reactive than yesterday.
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.