Confidence
Fair - Track of incoming weather is uncertain on Wednesday
Weather Forecast
A strong northwesterly flow will direct most of the precipitation associated with the incoming storm on Wednesday south of the border, meaning this region will either stay dry or have light snowfall of up to 5 cm. Winds will be light from the west during the day on Wednesday, picking up to moderate to strong overnight. Treeline temperatures will be cold--around -15C. On Thursday, the region should stay mostly dry and cold, although freezing levels may start to rise by the end of the day. On Friday, a punchy frontal system hits the region, bringing heavy snowfall and strong southwesterly winds. Freezing levels could rise to around 1500 m.
Avalanche Summary
On Saturday, numerous avalanches were triggered by skiers and explosives. A few small, skier-triggered avalanches were reported on Sunday and on Monday. They all failed in, or at the base of, the storm snow.
Snowpack Summary
Around 10 cm new snow was added Monday night to bring storm snow totals (since Friday) to between 15 and 40 cm. Southwesterly winds have now had a chance to blow this low density, cold snow around and as a result, fresh wind slabs are prevalent on lee slopes in exposed areas. Below the storm snow lies a rain crust at lower elevations (up to around 1800 m) and old wind slabs/sastrugi in exposed areas at higher elevations. I would be suspicious about the interface between the old layers and the new storm snow. Reports indicate there is not a lot of surface hoar around (likely blown away). However, the cold temperatures likely mean facets will be preserved. Acting in conjunction with a rain crust or a hard wind slab layer, this could set up some touchy slab avalanche conditions in the upper snowpack. Concern for lower snowpack layers has diminished and remains only in shallow snowpack areas. Facets associated with a crust from mid-December and/or sugary facets at the base of the snowpack may still be a concern in shallow areas. Fragile cornices are still looming.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.
Loose Dry
Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.