Regions
Banff Yoho Kootenay.
Lake Louise area has had more wind effect and more recent avalanche activity. Alpine hazard is rated CONSIDERABLE in this area.
Weather Forecast
A mix of sun and cloud for Wednesday. Temperatures will moderate somewhat with day time highs in the alpine reaching -14. Winds will be light to moderate from the north. Thursday may bring some isolated flurries along the divide.
Snowpack Summary
20-30 cm of last weeks storm snow sits over top of a very weak (Dec 19 layer) facet layer which in turn sits on the Nov 12 crust. Winds over the past week have created wind slabs in exposed areas. In many places these wind slabs sit on a weak snowpack comprised of facets and depth hoar.
Avalanche Summary
No new natural avalanches reported today, however a field trip in the Lake Louise area showed numerous avalanches up to size 2.5 from the past four days. These mostly initiated as windslabs and then stepped down into the weak facet layer below. Of note were four avalanches up to Class 2.5 in the Corral Slide Paths adjacent to Lake Louise Ski Resort
Confidence
Wind effect is extremely variable
Problems
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.
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.