Regions
Banff Yoho Kootenay.
Although natural activity has diminished and the danger levels have dropped to moderate, human triggered avalanches remain possible with this generally weak and variable snowpack.
Weather Forecast
The west winds that picked up this morning promise to bring a band of moist weather from the coast. Expect overcast skies with the potential for light precipitation and possibly strong winds with warmer temperatures Sunday. After this weather passes expect at return to clear skies and colder temperatures Monday.
Snowpack Summary
10 to 20cm of snow from last week overlies a generally weak and facetted mid-pack and base - particularly in the Lake Louise area and on the east side of Hwy 93 north. Closer to the divide, deeper snowpacks are stronger and more supportive. Surface hoar up to 10mm was buried by a trace in some areas this morning and West winds began in the alpine.
Avalanche Summary
Yesterday: Only 1 size 3 was triggered from the top of Mt. Whymper sliding on a layer near ground with avalanche control efforts. Also, 1 recent natural was observed on a North aspect where a cornice failure triggered a size 2 slab. Despite this minimal avalanche activity, there is still little confidence in the overall weak snowpack structure.
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.