Avalanche Forecast
Regions: Northwest Coastal.
Avalanche danger will increase over the day as snow accumulates and slabs build.
Confidence
High - We are confident the likelihood of avalanche will increase with the arrival of the forecast weather.
Weather Forecast
TUESDAY NIGHT: Cloudy with snowfall, accumulation 1 to 3 cm, 30 km/h southwest wind, alpine temperature -6 C.
WEDNESDAY: Cloudy with snowfall, accumulation 10 to 15 cm, 50 km/h southwest wind, alpine temperature -4 C.
THURSDAY: Cloudy with snowfall, accumulation 30 to 40 cm, 60 km/h southwest wind, alpine temperature -2 C, freezing level 1200 m.
FRIDAY: Cloudy with intermittent snowfall, accumulation 2 to 5 cm, 40 km/h west wind, alpine temperature -3 C, freezing level 800 m.
Avalanche Summary
Many storm and wind slab avalanches were triggered naturally, by explosives, and by riders on Sunday and Monday. They were generally in alpine and treeline terrain above 1200 m and they varied from 20 to 100 cm deep, forming small to large (size 1 to 3) avalanches. The avalanches released on the weak layers described in the snowpack summary in the north of the region.
Avalanche activity is anticipated to increase during Wednesday's storm, particularly into the evening as the snow rapidly accumulates.
Snowpack Summary
Wednesday's storm should drop around 10 to 15 cm of snow by sunset, with strong southwest wind. New wind slabs are expected to form during the storm, as well as storm slabs as the storm strengthens Wednesday night. This snow will overly previously touchy wind slabs in terrain exposed to the wind. Below around 1300 m in the south of the region, the snow will fall onto a hard melt-freeze crust.
Two weak layers may be found. A layer of surface hoar that formed mid-January may be found around 50 cm deep, particularly around Bear Pass and in the north of the region. A layer of sugary facetted grains may be found about 50 to 100 cm deep, which formed during the cold spell in late December to early January. To date, these layers appear to be most problematic in the northern half of the region.
The remainder of the snowpack is mostly strong in the south of the region. In the north of the region, the base of the snowpack consists of faceted grains around a melt-freeze crust, which is currently dormant.
Terrain and Travel
- Wind slabs are most reactive during their formation.
- Avoid freshly wind loaded terrain features.
- Be careful as you transition into wind affected terrain.
- When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.
Avalanche Problems
Wind Slabs
New snow and strong wind are expected to form new wind slabs in lee terrain features in wind-exposed terrain. These will sit on potentially reactive wind slabs formed during last weekend's storm. Snow may slide easily below treeline, where it will fall onto a hard crust.
Aspects: North, North East, East, South East, South, North West.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 1 - 2.5