Regions
Banff Yoho Kootenay.
Hazard is rated Low in the morning below tree-line. It may rise to Considerable in the afternoon with rising freezing levels and temperatures, especially if there is any sun affect.
Weather Forecast
Another good freeze tonight. Light flurries and showers begin tomorrow with freezing levels rising to 2100 m. They will remain there through Wednesday and Thursday night as the front passes through the region. In the alpine, expect 5-10 cm on Thursday and 5 cm Friday and rain below treeline. Local amounts may vary across the region.
Snowpack Summary
On shaded aspects or in the high alpine, up to 20 cm of low density snow sits over a firm 100 cm+ slab resting over weak basal facets at all elevations. Tests show sudden collapse results in these facets. A melts freeze crust is widespread below treeline & steep solar aspects at treeline & above. Windslabs are specific to immediate alpine lees.
Avalanche Summary
A little cooler today overall and no new avalanches were observed.
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.
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.