Moderate danger on Monday hinges on snowfall arriving late in the day. Look to Tuesday's forecast if snow is piling up around you.
Confidence
Moderate - Timing of incoming weather systems is uncertain on Monday
Weather Forecast
Monday: An incoming storm will deliver 15-25cm of new snow, intensifying in the evening. Winds will be strong from the southwest. Freezing level to 700 metres with alpine temperatures near -7.Tuesday: Continuing snow with 10-15cm accumulating. Winds moderate gusting to strong from the southwest. Freezing levels rising to 1000 metres with alpine temperatures of -6.Wednesday: Lingering flurries delivering 5-10cm of new snow. Winds moderate gusting to strong from the southwest. Freezing levels dropping to 800 metres with alpine temperatures of -9.
Avalanche Summary
Recent reports include a natural size 2 cornice release from an northwest aspect in the upper Soo area. Ski cuts and skier traffic continue to produce size 1 avalanches in isolated pockets of wind slab as well as size 1 loose dry avalanches in steep terrain. A MIN report from Saturday in the Pemberton Icefield area neatly demonstrates the potential for wide slab propagations on wind loaded features.
Snowpack Summary
Snowfall from Thursday and Friday deposited 5-20cm of new snow on the surface. Strong winds have continued to redistribute this snow in high elevation and wind exposed areas. Where it hasn't blown away, the new snow lies above a variety of hard surfaces that may include sastrugi, wind crust and hard wind slab. Strong to extreme winds formed these surfaces and caused significant wind redistribution of the underlying storm snow from earlier this week. This 30-50cm of storm snow overlies a variable snow surface from last week that includes either weak faceted snow or surface hoar in sheltered areas at treeline and below. The widespread mid-November crust is buried 1-2m deep in the snowpack. Recent snowpack and explosive tests have shown the crust to be unreactive, but it could remain a problem in shallow alpine start zones.
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.