January 15th surface hoar layer is reactive and has a ready storm slab sitting on it waiting for a trigger.
Weather Forecast
Below freezing temperatures, limited precipitation, light to moderate Southerly winds and the possibility of the sun coming out are the forecast for the next couple of days. Solar triggered slides may occur on steep solar aspects with prolonged sun exposure
Snowpack Summary
45cm of storm snow overlies the January 15 surface hoar layer and on steep due south terrain a sun crust. Strong south through west winds have redistributed the storm snow onto alpine lee slopes and ridges. Wind effect has caused surface slabs and heavy skiing. The December 17 surface hoar layer is down 80-130cm sitting on a crust below 2100m.
Avalanche Summary
A widespread natural avalanche cycle occurred yesterday and into last night. Large avalanches up to size 3 were observed and reported yesterday afternoon both in the back country (Connaught Creek) and the highway corridor. Human triggered slides were reported on McGill two days ago. The January 15 layer is touchy and reactive.
Confidence
Due to the number and quality of field observations
Problems
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.
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.