Regions
Banff Yoho Kootenay.
Deep lingering instabilities continue in the area. Despite the strong post-storm feel to the upper snowpack, the threat of large, catastrophic avalanches limits travelers to safer, non-avalanche terrain. Please continue to play safe.
Weather Forecast
Light snow is expected Friday with more wind and cold temperatures. This is unlikely to significantly change the avalanche danger rating in the short term.
Snowpack Summary
Windslabs are common in open areas with loading on easterly aspects. Commonly, a deep slab overlies midpack weaknesses of surface hoar, crusts, and facets. The depth of these slabs varies from 75 cm to 150 cm. These layers have been producing very large avalanches over the past week.
Avalanche Summary
Several new avalanches were noted today on the Icefields Parkway associated with recent winds.
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.
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.