Regions
Banff Yoho Kootenay.
It looks like a warm, windy, stormy day on Saturday. It is probably a good day to stay conservative with your terrain choices, and minimize exposure to overhead hazard. Recently any small changes in weather inputs have triggered large avalanches.
Weather Forecast
Between 5 and 10cm of snow is forecast for Saturday with strong west winds. Freezing levels will hover between 1600 and 2000m with valley highs in the East around 10'C. A cooling and clearing trend will start on Sunday.
Snowpack Summary
10-20 cm of recent snow sits over a firm 100 cm+ slab which rests precariously over the weak basal facets at all elevations. Tests show easy to moderate sudden collapse results in these facets. The surface snow is of a mix of soft snow in the shade, sun crust on sun exposed slopes in the alpine, and melt-freeze or isothermal snow below treeline,
Avalanche Summary
A few loose wet slides were reported on Friday from the local ski areas. These occurred below treeline on South and West aspects in steep terrain as the day warmed up.
Confidence
Freezing levels are uncertain on Saturday
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.