Regions
Banff Yoho Kootenay.
Watch for increasing overhead hazard as the new snow arrives with strong winds and warming temperatures. Minimize your exposure to cornices or large start zones, and expect sluffing out of steep terrain.
Weather Forecast
Snow has started to fall in the Western areas of the region. The next several days will have moderate precipitation, strong to extreme West winds, and warming temperatures with freezing levels hovering around the 2000m level in most of the forecast region, with higher freezing levels in the East.
Snowpack Summary
The snowpack remains fundamentally weak. Snowpack tests continue to produce moderate to hard sudden results on the Dec. 18th interface/basal weakness which has become one and the same in most areas with less than 1m of snow. New snow, warming temperatures and strong W winds will create more of a surface slab over the next few days.
Avalanche Summary
No natural avalanches observed in the last 48 hrs. We are still experiencing whumphs in some open areas below tree line in the Little Yoho region indicating human triggering of deeper weak layers is still possible in the right terrain.
Confidence
Intensity of incoming weather systems is uncertain
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.
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.