Regions
Banff Yoho Kootenay.
Wait a little bit longer for the storm snow to settle. Human triggering still likely. Make conservative terrain choices.
Weather Forecast
A short pulse of precip came through Bow Summit today that deposited about 5cm of snow. It is expected to clear tonight and into tomorrow. Temperatures will remain seasonal. The wind has been over forecasted of late, but expect moderate velocity from the SW.
Snowpack Summary
Up to 70 cm of storm 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 80-120cm 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. Wide propagations were observed near Serac Creek in Kootenay National Park today. They likely ran in the height of the storm (Friday). They were reported as approx 40cm deep and size 2.
Confidence
Intensity of incoming weather systems is uncertain on Wednesday
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.