Regions
Banff Yoho Kootenay.
Natural activity has tapered, but any slope that hasn't avalanched is primed for human triggering. More avalanche control using explosives today triggered avalanches with every bomb and up to size 3.5!
Weather Forecast
Tuesday looks to be cold, partly cloudy and dry and then we will see warmer temperatures and some light precipitation starting Wednesday and into Thursday. Only 5- 15 cm is expected by end of day Thursday. Winds will be moderate SW increasing to strong on Thursday.
Snowpack Summary
Up to 70 cm of recent snow with variable wind effect has put a dense load over the persistent weak layers. In thicker snow pack areas, the Dec. 10th weak layer of facets is now down 100-150cm with a stronger snowpack below. In thin snowpack areas, the Dec.10th layer is mixed in with the basal facets and October crust.
Avalanche Summary
The natural avalanche cycle has tapered off, but conditions are still primed for human triggering. Avalanche control using explosives today on the Icefields Parkway and Mt Dennis in Yoho produced results up to size 3.5 with every shot producing a large avalanche. Some avalanches were triggered with just the force of the bag hitting the slope.
Confidence
Due to the number and quality of field observations
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.
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.