Yesterday, we transitioned the persistent slab into a deep-persistent slab problem and this will likely remain for some time. Conservative terrain choices are recommended.
10-25 cm of snow has fallen over the past several days with moderate S-W winds. This has formed soft wind slabs in lee areas. These slabs are relatively soft and small but still possible to trigger. The major concern is that if triggered, these may step down to the weak basal facets and result in larger avalanches.
A 20-50 cm soft slab has formed over the very weak basal facets, with thin crusts at the interface in some locations. Human triggering is likely in steep terrain anywhere this slab is present, and whumpfing and cracking have been observed in many locations. Treat all steep terrain with caution. This problem will remain for the foreseeable future.
Temperatures are expected to be relatively warm over the next few days with the alpine reaching -7 and the valley's close to zero. No significant precipitation will occur. Alpine winds are going to die down to the light range on Monday.
Lake Louise ski patrol was able to trigger two size 2 avalanches with explosives today, both had fracture lines as deep as 50cm. Notably, a member of the Sunshine patrol triggered a size 2.5 (skier accidental, deep persistent slab) that was 60 meters wide and averaged 75cm deep. The bed surface was on the ground. The patroller was able to ski out to the side safely. Also, they produced many size 1 avalanches with ski cuts and explosives.
Recent snow and moderate SW winds have formed wind slabs at higher elevations. In most other areas, 20-50 cm of snow is forming a soft slab over a very weak base of facets, with occasional thin crusts at the interface. Average snowpack depths at treeline are between 60 and 90 cm.
