Regions
Banff Yoho Kootenay.
The avalanche hazard will rise overnight and into Saturday with additional snow and wind. Northern areas will receive the greatest amounts. Stick to more conservative lines and avoid steep overhead terrain until the new snow has a chance to bond.
Weather Forecast
Snow through Saturday with forecast amounts from 10-25 cm at treeline. Northern areas will see the highest amounts. Winds remain in the moderate range with strong gusts out of the SE to SW depending on how the cold front behaves. Temperatures remain in the -5 to -15 range before plummeting Saturday night. Flurries and very cold temps on Sunday.
Snowpack Summary
15-25 cm of new snow with moderate SW-SE winds is building slabs in lee areas of the alpine. The mid-pack is quite dense above the Dec 10 interface down 70-140 cm. In shallower snowpack areas weak facets exist below the Dec 10 interface, with moderate-hard test results in the facets. In deeper snowpack this basal weaknesses is less pronounced
Avalanche Summary
Local ski hills reported ski cutting small loose dry and wind slabs up to size 1.5 on Friday in steep lee areas. No reports or avalanche observations from the back-country, but we expect an increase in avalanche activity over the next 36 hrs.
Confidence
Timing, track, or intensity of incoming weather system is uncertain on Saturday
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.