Northwest Coastal

Avalanche danger will increase as a major storm brings heavy wind and snowfall to the region starting Thursday.

Thursday: 10 cm / strong winds from the southwest / freezing level at 500m and rising. Friday: 20-40 cm / strong to extreme winds from the southwest / freezing level up to 1200m. Saturday: 15-25 cm / strong winds from the southwest / freezing levels dropping to 300 m.

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On Tuesday, wind slabs were reported in the Stewart area with natural size 2 avalanches in steep north-facing alpine terrain as well as several size 1.5-2 wind slabs triggered by explosives on north to northwest facing alpine slopes. Last week, several natural and skier triggered avalanches up to size 2 were reported on buried surface hoar in the Shames area. The incoming storm will build bigger wind slabs and possibly reawaken the surface hoar layer, as it's forecast to bring heavy precipitation, strong winds, and rising freezing levels.

The start of a major storm will bring 10 cm of new snow by Thursday afternoon. Wind speeds are expected to steadily increase throughout the day, forming touchy wind slabs in the alpine and on exposed features at treeline. The new snow will fall on 30-50 cm of rapidly settling storm snow from earlier this week. Reports from the Shames area suggest a buried surface hoar layer exists 50-80 cm below the surface and sits above a firm supportive crust. The layer was reactive to light loads on south-facing alpine slopes last week, but recent reports suggest it is gaining strength. Treeline snow depths are around 150 cm in the Terrace and Stewart areas, but substantially less further north. Snow in these thinner areas, such as Ningunsaw, may be facetting and developing weak basal layers.