Happy New Year! The deep weak layer has potential to be human-triggered on large, steep, convex unsupported terrain. A special avalanche warning has been issued which includes our region. Once the warning expires, it is critical to consider that the deep weak layer will linger for sometime. Don't let it surprise you especially after nothing has happened for a while.
Surface snow and strong winds have formed a slab over the December 17th facet layer 25-50cm down. This is most significant at tree line and in the alpine in exposed locations and exists in some areas below tree line. If triggered, it can 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.
There was no field patrol on Saturday or Sunday. Wednesday and Thursday's explosive control on some low targets along the Icefields Parkway produced several large slab avalanches in wind loaded tree line slopes. They triggered as the persistent slab and stepped down to the ground. In addition, below tree line slopes produced small slab avalanches. Numerous natural avalanches up to size 2.5 were also observed in the alpine along the Icefields Parkway 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. Facets and depth hoar make a weak base in most areas. Snow height ranges from 50-120cm.
Monday will have clouds, sun, light winds, and -3 °C. Tuesday will be very similar to Monday. Wednesday will be clouds, sunny periods, and cooler temperatures at -11 °C. Thursday will warm up to -6 °C with light winds and clouds.
