Snow amounts will continue to gradually accumulate over a variety of potential weak layers in the coming days.
Confidence
Moderate - Intensity of incoming weather systems is uncertain on Wednesday
Weather Forecast
TUESDAY: Mainly cloudy with periods of snow in the afternoon and overnight, accumulations 10-20cm / wind moderate east / alpine temperature -11 WEDNESDAY: Cloudy with sunny breaks and isolated flurries / wind light northeast / alpine temperatures -12 THURSDAY: Mainly cloudy with isolated flurries / wind light to moderate northwest / alpine temperature -8
Avalanche Summary
Recent reports indicate explosives controlled and natural storm snow avalanches to size 2.5 in the alpine and tree line .As snow accumulates and settles in the coming days expect to see an increase in avalanche activity.
Snowpack Summary
The 20-40 cm of new snow accumulating through the weekend now sits on a wide variety of old surfaces including large surface hoar (weak, feather-like crystals), hard crusts formed by sun or wind, and sugary facets. As the snow load builds and slab properties develop, it will be important to monitor how the new snow is bonding to the old surfaces. Most concerning would be areas that have surface hoar sitting on top of a hard crust. A crust which was formed by rain in late November is a major feature in the snowpack and is down approximately 60-80cm at tree line elevations. Snowpack tests suggest the snow above is currently bonding well to it. Snowpack depth decreases rapidly below tree line. Look out for early season hazards such as rocks, stumps, and open creeks.
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.
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.