Lingering deep persistent weaknesses remain a concern in isolated areas. Check out the new blog video from our field team at http://www.avalanche.ca/blog for the latest update on local conditions.
Weather Forecast
A weak storm should limp into the South Rockies Sunday night bringing 1 - 3cm. The region could pick up a few cm Monday night but it looks high and dry for Wednesday and Thursday. Models are starting to converge around the idea of yet another shot of warm air otherwise known as Pineapple Express on Friday. Ugh.
Avalanche Summary
No new avalanches have been reported. On Wednesday a size 2 avalanche was accidentally triggered on an east aspect in the alpine by a sledder near Racehorse Pass (Crowsnest) on the December persistent weak layer.
Snowpack Summary
Recent sunny weather and high freezing levels have decimated the lower elevation snowpack. As a result the threshold for avalanches in most of the region has risen to approximately 1600m, potentially higher on solar aspects. 4-8cm of new snow has covered up a melt freeze crust and/or surface hoar, or a combo of both. The melt freeze crust exists up to approximately 1900m and up to all elevations on solar aspects. Time will tell, but I suspect this new layer will likely cause problems down the line and is a good one to keep in mind as it becomes buried deeper over time. The mid-December crust/facet/surface hoar layer is down 40-85cm and is suspected to be reactive in isolated areas, especially where a slab of stiffer snow has consolidated above it. This layer has proven easier to trigger from shallow and rocky areas in the alpine and treeline.
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.