Regions
Banff Yoho Kootenay.
We carefully move the avalanche danger ratings to Low at all elevations today. We have taken our time with this, and remind people that the snowpack is not strong. Slight changes in weather will reawaken those facets.
Weather Forecast
The arctic high continues to establish itself over BC and Alberta, with temperatures for Monday expected to drop to -26; highs of -20. No snow in the forecast for the week ahead, and light winds from the north.
Snowpack Summary
The snowpack has gained strength over the past few weeks, and the facetted base layer has gone dormant for now (it will wake up again!). Snowpack tests are now producing hard results 20 cm above the ground. The current clear spell has left 10 cm of loose snow sitting on top of a bombproof windslab above treeline, and a thick crust on S & W aspects.
Avalanche Summary
No new avalanches have been observed or reported.
Confidence
The weather pattern is stable
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.