This forecast assumes an intense storm overnight Saturday. If the storm fizzles, the danger ratings may be a tad too high.
Confidence
Fair - Intensity of incoming weather systems is uncertain on Saturday
Weather Forecast
Overnight Saturday, 20-40 cm snow is expected to fall above about 1000 m, with rain at lower elevations. This snow comes with strong SW winds. There's a possibility of a temperature spike during the storm, but weather models are not in agreement. By late Monday, precipitation and wind are expected to ease. Light snow is possible on Tuesday.
Avalanche Summary
Explosives and skiers triggered size 1-2 wind slabs on lee and cross-loaded terrain on Friday. I expect the size and likelihood of avalanches to increase overnight Saturday in response to snowfall and strong winds.
Snowpack Summary
Two recent pulses of snow accompanied by strong S-SW winds have built deep wind slabs above a hard crust and/or surface hoar. The buried crust is most pronounced between about 1500 m and 2200 m. The distribution of the surface hoar seems spotty across the region, but some operators found it to be widespread in their tenure before the snow began burying it. Where the surface hoar exists, whumpfing is already indicating the touchiness of this interface. Deeper snowpack weaknesses (curst/facet and/or surface hoar layers formed in November and December) have fallen off the radar, but they could be reawakened with a very heavy load (like a cornice fall or wind slab) in the wrong spot (like a thin snowpack area, or high elevation northerly aspects where there is no strong crust above).
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.
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.