Northwest Coastal

Light snowfall and more strong winds are keeping our wind slab problem on life support. A concerning pattern of persistent slab activity has emerged in the north of the region, where you should consider the danger to be one step higher than posted.

High -

Thursday night: Increasing cloud. Light southeast winds becoming strong southwest or south in early morning.Friday: Cloudy with flurries bringing about 5 cm of new snow, decreasing overnight. Strong to extreme southeast winds. Alpine high temperatures around -3.Saturday: Cloudy with continuing flurries bringing about 5 cm of new snow, increasing overnight. Moderate to strong southeast winds. Alpine high temperatures around -3.Sunday: Cloudy with decreasing flurries bringing about 5 cm of new snow and new snow totals to around 25 cm. Moderate southwest winds.. Alpine high temperatures around -5.

No avalanches were observed in most of the region on Wednesday and Thursday, but in the far north near Ningunsaw, two large (size 2 and size 3) remotely (from a distance) triggered persistent slabs were observed failing over a 20-50 cm-deep layer of surface hoar over sun crust. This has brought persistent slab problems to the centre of our attention for backcountry travelers in the north.Storm slab avalanches up to size 3 continued to be reported into Sunday after the warm and wet storm that hit the region at the end of the week. Storm slabs are now likely stabilized, but strong winds have been keeping wind slab problems alive in the alpine. Continuing wind and light new snowfall has wind slabs still firmly on the radar for Friday.An avalanche incident was reported in the Shames backcountry area last Thursday. The incident involved two skier triggered avalanches occurring in succession with two people involved and partially buried. The details can be found on the Mountain Information Network. (here)

A warm and wet storm brought up to 100 mm precipitation between Wednesday and Sunday last week, with rain falling as high as 1500 m. Forecast outflow winds, although mainly expected at lower elevations, may be blowing the new snow into new wind slab deposits at higher elevations. The snow is crusty at lower elevations, with little snow available to be transported by the wind.In some sheltered areas that were unaffected by rain, the new snow is sitting on a weak layer of surface hoar (feathery crystals). This layer has been identified as the failure plane in several recent large avalanches in the north of the region.For most of the region, a weak layer of facets (sugary snow) buried in early December exists down 180-250 cm. The likelihood of triggering this layer is decreasing, but it could be triggered by humans in shallow snowpack areas, particularly in the north of the region. The potential may also exist for storm slab avalanches to step down to this layer, resulting in large avalanches. A combined crust/facet layer may also be found at the base of the snowpack in alpine areas. It is suspected to have been involved in several large 'step down' avalanches during the storm.