Purcells

Poor - Track of incoming weather is uncertain on Wednesday

There is high uncertainty with the weather for Wednesday and into Thursday. Some forecast models are calling for light to moderate snowfall with associated winds, while others are calling for dry and mostly clear. It all has to do with the track of a frontal system that's primarily heading south of the region. If heavy loading from snow or wind does occur, then expect avalanche danger to increase.

Recent reports indicate loose natural and skier triggered sluffing to size 1.5 in steep terrain. In addition a report of a skier triggered avalanche size 2 on an east aspect in the alpine. Explosives testing in the southern portion of the region on Friday (size 3.5 on a north aspect at 2700m with 200cm fracture) indicates that avalanches are capable of stepping down to deep basal facets with heavy loads. Cornices have also been failing and could be a heavy trigger for wind and persistent slabs on the slope below.

20-45 cm of low density recent storm snow is being redistributed by westerly winds forming weak wind slabs and cornice tabs on lee aspects, but remains fluffy and cohesionless in most sheltered areas. This new snow is bonding poorly to a variety of surfaces (facets, surface hoar in sheltered areas, wind crust, soft slabs and hard slabs).The mid-December surface hoar/facet persistent weakness, now down around 50cm on the eastern side of the range and as deep as 150cm on the western side, is generally producing anywhere from easy (where it's shallow) to hard (where it's deeper) test results. But all tests consistently show a high propensity to propagate fractures. Basal facets remain a concern for human triggering in shallow snowpack alpine areas and for step down fractures in more consolidated snowpack areas.