Natural avalanche activity has tapered off but human triggering of our persistent and deep persistent slab problems remains possible. Conservative terrain choices and group management recommended for the foreseeable future. Please see this MCR for a more detailed description of conditions down south.
Previous strong winds have formed a slab over the December 17th facet layer 25-50cm down. This problem is most significant in the alpine and exposed tree line features but also exists in some areas below tree line. If triggered, it is likely to step down and initiate a deep persistent slab on the basal facets near ground.
The bottom of the snow pack is inherently weak with well developed Facets and Depth Hoar. Avalanches initiating in the upper snowpack are likely to step down to this layer and gain significant mass.
One size 2 persistent slab was observed Monday across from the Stutfield viewpoint initiating in extreme terrain and scrubbing to ground. Explosive control at Marmot ski area continues to produce avalanches stepping to the basal facets in the alpine including a size 2.5 on Sunday. Last weeks explosive control along the Icefields Parkway produced several large persistent slab avalanches in wind loaded tree line slopes also stepping down to our basal weakness. Numerous natural avalanches up to size 2.5 in the alpine and a few thinner slabs below tree line were also observed on these same days.
20-30 cm of surface snow has developed into a persistent slab over the December 17th facets. Alpine and tree line slopes are heavily wind affected and variable with many exposed features scrubbed down to ground. The mid and lower snowpack is heavily faceted with depth hoar continuing to develop at the base. Snow height ranges from 50-120cm.
A surface ridge of high pressure will continue to dominate the forecast through the end of the week. Clear skies on Wednesday with light southwest winds. The ridge will weaken slightly on Thursday bringing increasing cloud; light precipitation is possible over the weekend. Temperatures will be seasonal with a slight warming trend into the weekend.
