The last few days' new snow sits on a variety of potential weak sliding layers. As the storm snow settles in the coming days, it will be critical to evaluate the bond between new and old snow layers.
Confidence
Moderate - Track of incoming weather systems is uncertain
Weather Forecast
Wednesday: Isolated flurries/ Moderate to strong southwest wind / Alpine temperature 0Thursday: Flurries, accumulation 10-15cm / Moderate southwest wind / Alpine temperature 1Friday: Cloudy with some sunny periods / Light north wind / Alpine temperature -3
Avalanche Summary
There are no new recent reports of avalanche activity, however I would suspect there to be continued potential for skier and rider triggering with the recent new snow, strong winds at upper elevations and a possible weak bond at the storm/old snow interface. There was natural avalanche cycle Sunday night into Monday morning with avalanche releases up to size 2. Reports indicated that avalanches to size 1.5 were being easily triggered with ski cuts.
Snowpack Summary
Up to 60cm new moist or wet new snow overlies the variable old snow surface from late last week, which includes well settled snow on southerly aspects, loose snow on shaded aspects, isolated pockets of surface hoar, and sun crusts on steep southerly aspects. With the potential for buried surface hoar means storm snow weaknesses from this latest storm will take longer than normal to stabilize. An old rain crust is reported to be down 150 cm in the North Shore mountains. This layer is still failing on snowpack tests, but is likely difficult to trigger in most places now.
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.