Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural and human triggered avalanches likely.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Regions
Banff Yoho Kootenay.
Continued natural activity today with touchy slabs at all elevations reacting easily to skier and explosive triggers. Avoid avalanche terrain. Avalanche control is planned on Mt Dennis and Mt Whymper Sunday. No skiing or climbing in these areas.
Weather Forecast
Winds and snow are forecast to back off overnight Saturday as a ridge brings cooler temps near -16C at 2000m. Temps will climb to -10C as winds pick back up to moderate SW later on Sunday. On Monday, expect temperatures to climb a bit and winds to stay elevated in the moderate range as the next wave of precip arrives from the Coast.
Snowpack Summary
40 - 60 cm of snow since Dec 10 forming a storm slab over facets and surface hoar. New windslabs are common on lee (mostly east) aspects. The lower snowpack is weak and facetted with some avalanches running to ground.
Avalanche Summary
Skier triggered avalanches at Emerald Lake and Wawa Bowl near Sunshine today with another close call in West Bowl at Lake Louise yesterday. Numerous natural and skier or explosive triggered avalanches over the past few days up to size 2.5 have been reported. Avalanches may run further downslope than expected, so be cautious of overhead hazard.
Confidence
Intensity of incoming weather systems is uncertain on Monday
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.