Regions
Banff Yoho Kootenay.
Avalanche control is planned for Wednesday, please avoid skiing and climbing on Mt. Field, Mt. Stephen, Mt. Bosworth, Mt. Whymper and the Simpson paths (previously known as the Vermillion paths).
Weather Forecast
NW flow aloft continues, and this moist air is colliding with cold arctic air somewhere over the Rockies. The majority of the precipitation from this storm is now over with only trace amounts expected overnight and tomorrow, but strong upper level winds and warming temperatures are expected for Wednesday.
Snowpack Summary
13 cm of snow in the last 24 hours brings the total storm snow since Jan 2 up to 30 cm. This storm snow remains mostly unconsolidated and has not yet formed into a cohesive slab except above 2500 m. Widespread cracking and whumphing observed today, and as soon as the surface snow forms a slab it will be easy to trigger.
Avalanche Summary
Several avalanches observed in the Field area, including one that ran over the ice climb Pilsner Pillar and another one from the Mt. Stephen cliffs that put 2.5 meters of debris on the railroad. Very limited observations from field teams and the ski areas today due to poor visibility.
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.