Confidence
Fair - Timing, track, or intensity of incoming weather is uncertain on Monday
Weather Forecast
Overnight Saturday: Another 5-10cm should bring storm snow amounts to 20-30cm.Sunday: Flurries. Cold temperatures, with the freezing level near valley floor. Northerly winds.Monday/Tuesday: Two main influences will battle for control of the region's weather: cold arctic air and a low pressure centre near Vancouver Island with an associated westerly flow. Expect some flurries, cold temperatures and the chance of strong outflow (northerly or easterly) winds if the arctic air dominates.
Avalanche Summary
No new avalanches have been reported, but I'd expect some sluffing of the dry new snow in steep terrain and possibly wind slab avalanches near ridge top to be occurring today.
Snowpack Summary
20-40cm of dry new snow has landed on a hard supportive crust in the Coquihalla area and dry facets in the Duffey Lake area. Initial reports from the Coquihalla area on Saturday indicated that the snow is bonding well to the crust. At ridgetop, south-westerly winds are likely to be creating wind slabs which may fail on the dry storm snow and/or the icy crust. Deeper in the snowpack, two persistent weak layers remain a concern only in thin snowpack areas (perhaps wind-scoured zones or relatively dry eastern ranges) and particularly in steep rocky terrain or sheltered, low-snowpack terrain. The two layers are surface hoar and/or facets associated with a crust from mid-December and/or sugary facets at the base of the snowpack.
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.