Northwest Coastal

Rain is switching to snow and new storm slabs are forming at higher elevations. Substantially greater accumulations are expected in the Bear Pass area. Consider avalanche danger to be HIGH in areas with over 30 cm of new snow.

Moderate - Forecast snowfall amounts are uncertain

Friday night: Cloudy with continuing wet flurries bringing 5-15 cm of new snow to high elevations and rain below about 1500 metres. Strong to extreme southwest winds.Saturday: Cloudy with flurries bringing around 5 cm of new snow, increasing in the evening. Rain below about 1100 metres. And possible new snow accumulations of up to 20 cm in the north of the region. Strong to extreme southwest winds. Alpine high temperatures around -1 with freezing levels around 1500 metres.Sunday: Sunny. New snow totals of around 15 cm, possibly up to 60 cm in the north of the region. Light northeast winds. Alpine high temperatures around -4 with freezing levels to 1000 metres.Monday: Sunny with increasing cloud. Light variable winds. Alpine high temperatures around +1 with an above freezing layer from 1000-2000 metres.

A large (size 2.5) wind slab was triggered remotely (from 20 metres away) just south of the Seven Sisters Provincial Park area on Wednesday. This occurred on a southeast aspect at 1700 metres and is believed to have failed on the roughly 50 cm-deep persistent weak layer described in our snowpack summary. This event highlights increasing slab properties of our storm snow in wind-affected areas as well as the potential for our persistent weak layer to exist in protected areas above 1500 metres.Looking forward, continuing snowfall will be layering new storm slabs on high elevation slopes and adding load to a now deeply buried weak layer. Saturday is another day to back off into simple terrain, stay clear of overhead hazards, and away from avalanche runout zones until the snowpack adjusts - especially in northern parts of the region.

5-10 cm of new snow (with more new snow on the way) has covered a new layer of surface hoar that may coexist with a crust on sun-exposed slopes. Below the surface, around 50 cm of recent low density snow covers a variable surface of wind-affected, faceted snow and possibly a weak layer of surface hoar in protected alpine areas, but more predominantly a rain crust/surface hoar combination below 1500 m. Reports from the Shames area suggest a strengthening bond between this recent snow and the supportive underlying crust now down 50-60 cm. Below the interface described above, the mid snowpack is strong, although exceptions may exist in the far north of the region where an older layer of storm snow may overlie a weak layer of surface hoar (feathery crystals). This layer was the failure plane in several large avalanches in the north of the region last week. It has not shown in reports elsewhere.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 generally low, but it could be triggered by humans in shallow snowpack areas, particularly in the north of the region.