A Special Public Avalanche Warning continues for this region. Conservative route selection and cautious decision-making is required.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
Synopsis: A ridge of high pressure should maintain dry conditions for the next couple days. Expect a mix of sun and cloud with the freezing level at valley bottom. Ridge winds are generally light. A weak system on Tuesday could bring more cloud, light snow, and rising freezing levels.
Avalanche Summary
On Friday, a large natural avalanche cycle to size 3.5 was reported by one operator near Valemount. Another observer just NW of Blue River reported an impressive natural avalanche cycle at and below treeline with numerous slabs up to 60 cm deep. The story may have been the same for other parts of the region.
Snowpack Summary
Heavy new snow and strong winds have created storm slabs in many places and wind slabs on features lee to the south. This will also add load and stress to the already volatile persistent slab. There are a couple of highly reactive layers of surface hoar buried in the upper snowpack, which have been responsible for recent avalanches. The mid and lower snowpack are generally strong, with any weak layers considered dormant for now. Snowpack depths are variable and shallow snowpack areas may have weak facetted crystals near the ground.
Problems
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
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.