Regions
Banff Yoho Kootenay.
The weak snow pack does not give us much confidence in steep terrain or large features especially at tree line and above where more of a surface slab exists. Stick to moderate angled, well supported terrain, and enjoy the recent snow fall!
Weather Forecast
Moderate alpine temperatures between -5 and -10'C with light winds out of the NW and a mix of sun and cloud are expected for the next several days.
Snowpack Summary
Wind slabs are present in many open areas above tree line. Below this the snow pack is quite weak and facetted in most places. The Dec 18 crust/facet interface is down 30-40cm at tree line and we are still getting lots of whumphing on this layer. The bottom half of the snow pack consists mostly of facets.
Avalanche Summary
Natural avalanche activity has tapered off but human triggering remains likely. A size 1.5 skier triggered avalanche occurred in the Wizard Chutes near tree line Jan 10th in the Sunshine area. Avalanche control at Lake Louise on Jan 9th resulted in a size 3 which initiated on the Dec 18th interface and then stepped down to facets near the ground.
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.