Northwest Coastal

An ongoing storm continues to drive high avalanche danger in the northwest.

Moderate - Forecast snowfall amounts are uncertain on Tuesday

Tuesday: Snow with rain at lower elevations. Accumulations of up to 30cm by late evening. Winds strong to extreme from the south. Freezing level around 1800 metres with alpine temperatures of +1.Wednesday: Periods of wet snow mixed with rain. Accumulations of around 15 cm. Winds moderate to strong from the south. Freezing level to 1500 metres with alpine temperatures around +1.Thursday: Mainly cloudy with isolated flurries and a trace of new snow. Winds light to moderate from the southeast. Freezing level to 1100 metres with alpine temperatures around 0.

A snowmobiler triggered a Size 2 storm slab in the Bear Pass area on Sunday, resulting in a partial burial. The entire depth of storm snow was involved in the avalanche, resulting in a 120 cm crown depth and 100 metre width. The incident calls attention to increased snow depths in wind loaded areas, as well as the touchy nature of our storm slab problem and the potential for wide propagations. Additional reports from Sunday revealed extensive and productive explosives control north of Stewart, with numerous storm slabs running Size 1.5-2 with crown depths of 20-50 cm. One Size 3 result was recorded.For Tuesday, expect our storm slab problem to remain very touchy as ongoing snowfall, high freezing levels, and strong winds promote rapid slab formation and easy triggering. Also keep in mind that a basal weakness continues to drive a low probability/high consequence problem for shallow snowpack areas, especially in the north of the region.

Anywhere from 40-80 cm of new snow now lies on the surface, the product of a storm impacting the northwest coastal region over the past few days. Precipitation has been falling as wet snow or rain at lower elevations. The new snow has buried widespread wind affected surfaces recently reported in exposed terrain, including scoured surfaces, sastrugi, and hard wind slabs. Faceting of surface snow was also taking place in the days before the storm as well as sun crust formation on steep solar aspects. In areas sheltered from the wind, the new snow may also bury 5-10 mm surface hoar. Below around 1100 m elevation, a rain crust can be found at or just below the new snow interface. Deeper in the snowpack, the mid-January surface hoar/facet layer is now down roughly 80-120 cm. Recent observations suggest the layer has generally stabilized but isolated weaknesses may still exist, mainly where buried surface hoar is still intact. Below this layer, the snowpack is generally strong and well settled. The exceptions are areas around Bear Pass and Ningunsaw where basal facets remain an ongoing concern, especially in shallow snowpack areas.