Regions
Banff Yoho Kootenay.
More snow forecast for Monday night, and we are soon to approach a tipping point in the avalanche hazard. All the small amounts of snow are adding up. Expect avalanche activity on Tuesday and Wednesday, and be wary of sudden changes.
Weather Forecast
A system embedded in a NW flow will cross the region starting Monday evening and tapering by Tuesday evening. Expect 10-15 cm of snow and rising temperatures with freezing levels reaching 1400 m in some locations on Tuesday. Winds will be light at treeline, but strong at the 3000 m level. Look for clearing starting on Wednesday.
Snowpack Summary
10-15 cm of snow is forecast to fall overnight on Monday, along with rising temperatures. This will form an easily triggered storm slab in windloaded areas at treeline and above. The lower snowpack is comprised of depth hoar and facets, and will soon to reach a tipping point where the new snow load and warming will begin to trigger the deep layers.
Avalanche Summary
No new avalanches have been observed or reported today.
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.