Regions
Banff Yoho Kootenay.
The snowpack is stabilizing after last week's storm, however isolated natural avalanche are still being reported. Despite improving trend, forecasters confidence is low. Caution is still warranted.
Weather Forecast
Boxing Day should be a mix of sun and cloud with occasional light flurries, but little in way of accumulation. Freezing levels will be at surface and winds will be light to moderate from the SW
Snowpack Summary
The snowpack has doubled since Dec 10, and is slowly stabilizing after last week's storm cycle. Deeper snowpack areas continue to show the Dec 10 SH layer down 60-80 cm with hard, but sudden column test results. In shallow snowpack areas, the basal facets are producing easy collapse test results and should not be trusted.
Avalanche Summary
There were several reports over the past 48 hours of natural avalanches (up to 1.5) from the Sunshine Back-country.
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.
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.