Regions
Banff Yoho Kootenay.
We are in a holding pattern and have little confidence in our snowpack at tree line and above. Continue to avoid steep or convex terrain especially if there are terrain traps below, and enjoy the good skiing on lower angled well supported slopes.
Weather Forecast
Cloudy overnight then clearing skies with cold temperatures and NE winds are forecast for Monday. A warming trend with continued clear skies is forecast for Tuesday and Wednesday.
Snowpack Summary
Recent winds have created small wind slabs in the alpine which sit over the Dec 18 layer of crust, facets and/or surface hoar depending on the location. A poor bond exists at this interface. At the base of the snowpack weak crusts and facets exist which are also a concern. Overall the snowpack is quite weak and does not inspire much confidence.
Avalanche Summary
A skier triggered size 1.5-2 avalanche was reported today in the Wizard Chutes near Healy Creek at approximately 1900m. It started as a small wind slab near tree line and then stepped down to the basal facets. Other small skier and explosive triggered wind slabs have been reported by the local ski areas in the last 48hrs.
Problems
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
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.