Regions
Banff Yoho Kootenay.
Friday marks a change in conditions with an incoming storm. Pay attention to new snowfall amounts and what the wind is doing.
Weather Forecast
Snow beginning on Friday with various models forecasting between 10 and 20 cm along the divide by the end of the day. More snow on Saturday (up to 30 cm) and then very cold arctic air settles in for Sunday. Winds forecast to be mod to strong from the SW on Friday.
Snowpack Summary
Extensive wind effect in alpine from last weeks strong winds. The mid-pack is increasingly settled (up to P) down to the Dec 10 interface (down 60-130 cm). In shallower snowpack areas weak facets exist below the Dec 10 interface, and stability tests show moderate-hard results within the facets.
Avalanche Summary
No new avalanche activity
Confidence
Intensity of incoming weather systems is uncertain on Friday
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.
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.