Avalanche Forecast

High -

Thursday night: Cloudy with increasing flurries bringing 5-10 cm of new snow. Light southwest winds, increasing to strong in the alpine.Friday: Cloudy with continuing flurries bringing 10-20 cm of new snow. Snowfall continuing overnight. Light southwest winds, increasing to strong in the alpine. Alpine high temperatures around -3.Saturday: Mainly cloudy with easing flurries bringing a trace of new snow and new snow totals to 20-40 cm. Light flurries continuing overnight. Moderate southwest winds easing over the day. Alpine high temperatures around -6.Sunday: Cloudy with flurries bringing 5-10 cm of new snow and new snow totals to 25-50 cm. Light southeast winds. Alpine high temperatures around -10 and dropping over the day.

On Tuesday we received two reports of small wind slabs that were intentionally triggered by skiers on steep east and northeast facing slopes in the alpine. There was also a report of a size 2 cornice failure above a southeast facing slope. In the neighboring Glacier National Park region a size 3 avalanche was skier triggered on a steep southeast facing slope in the alpine. More details and photos here.For the most part, avalanche activity really slowed down Monday. That being said, a size 2 natural wind slab was reported from a NE facing feature at 2600 m. A small (size 1) avalanche was reported from a steep northeast facing slope below treeline at 1300 m, which failed on the surface hoar. Activity on this interface has decreased in the last 72 hours, but this MIN post and this one do a great job of illustrating the nature of this problem which is most prevalent between 1200 and 1800 m. This MIN is a bit older, but it also offers a great visual of this mid and low elevation problem. This interface will likely wake up as storm snow begins to stack up over the weekend.

New snow has begun to accumulate on the previous surface, which consists of a mix of sastrugi, stubborn old wind slabs, facets, crust and surface hoar. The new snow is unlikely to bond well to these surfaces over the near term.Last weekend's warm and windy weather left a crust up to 3 cm thick on steep south and some west facing aspects and redistributed quite a bit of snow into wind slabs in lee features at treeline and above. These older wind slabs are now probably only suspect in extreme terrain. The warmth also allowed 25 to 60 cm of older snow to continue to consolidate above the mid-January persistent weak layer (PWL). This PWL is made up of large surface hoar that is most prevalent at and below treeline, with enhanced reactivity noted between 1400 and 1800 m. On steep solar aspects this interface presents as a crust, there may be locations where the surface hoar actually sits on the crust. Potential exists for this layer to become increasingly reactive as new snow adds load to the snowpack. Slab releases or loose snow avalanches formed of new snow may also act as a trigger for this layer.The middle and lower portions of the snowpack are generally well-settled and strong.