Purcells

Monitor the storm carefully. If overnight amounts exceed 20 cm and there is wind, bump the danger rating up to high.

Moderate - Forecast snowfall amounts are uncertain

MONDAY NIGHT: Around 5 cm new snow expected. Strong southwesterly winds.TUESDAY: 5-15 cm additional new snow with freezing level around 1400 m. Strong southwesterly winds.WEDNESDAY: 2-4 cm new snow. Freezing level around 1300 m. Moderate westerly winds.THURSDAY: Around 5 cm new snow, increasing through the day. Freezing level around 1000 m. Moderate southeasterly winds.

Extensive recent avalanche activity has occurred in the Purcells since December 12, although natural avalanche activity started to subside on Sunday and Monday. Human-triggered avalanches remain a concern and on Sunday, a small sluff triggered by a skier stepped down and released on a deeply buried weak layer (likely basal facets). Another very notable avalanche occurred on Saturday when a size 2.5 avalanche was remotely triggered from 50-100 m away on a northwest aspect at 2250 m. A report of this avalanche can be found on the Mountain Information Network. (here)

60-120 cm of snow sits on a weak layer of facets (sugary snow), surface hoar (feathery crystals), and a sun crust (on south facing slopes). Strong winds have promoted widespread slab formation.Another layer of surface hoar and sun crust is now buried 80-150 cm. The potential may exist for smaller avalanches to step down to this deeper layer, resulting in very large avalanches. The most likely areas for this layer to be a problem is where the surface hoar sits on the sun crust, which is most likely on steep south facing terrain at treeline.At the base of the snowpack is a crust that formed in late October. This layer is likely only a problem on large, steep alpine features with a shallow snowpack. It would likely take a large trigger, such as a cornice fall, to produce an avalanche on this layer.