Avalanche Forecast
Regions: Babine, East Stikine, Hudson Bay, Kispiox, Microwave-Sinclair, Northwest Inland, Telkwa.
The snowpack remains sensitive to light triggering. Expect as the strong winds and new snow continues, an already reactive wind slab will amplify in size.
Adopt terrain travel strategies that avoid steep areas on north-aspect terrain that will certainly harbor new and existing reactive wind slabs.
Confidence
Moderate
Avalanche Summary
On Saturday both vehicle and skier remotely triggered avalanches have been reported. These avalanches were large (size 1.5 to size 2.5) and found on north aspect terrain between 1500 and 1600 m. A naturally occurring avalanche was reported as very large (size 3) in the same vicinity of the remote trigger avalanches.
Friday, poor visibility obscured observations. Avalanches were heard from steep terrain with powders clouds observed pluming out of lower runouts. Near Hazelton, one large (size 2) was observed, this naturally occurring avalanche was on a north aspect at 1600 m and was suspected to be initiated by a cornice collapse.
The incoming storm is forecast to bring to the area, strong southerly wind and light snowfall. Expect continued formation of fresh wind slabs and building weak new cornice features. Avoid wind-loaded areas at upper elevations and keep in mind the potential for deeper instabilities to produce large and surprising avalanches.
Snowpack Summary
At upper elevations, southerly winds have scoured windward areas and redistributed past storm snow into wind slabs in lee areas. Wind slab depth has been reported up to 50 cm in depth.
Several persistent weak layers may be found in the top meter of the snowpack. Most prominently, a layer of surface hoar buried in early January is now 20-50 cm deep and is reactive to skier traffic. A weak layer of facets and/or surface hoar buried in late December is now down 70-110 cm.
In alpine terrain, triggering one of these layers is most likely on steep rocky slopes where they present as facets. In treeline terrain, the layers are most likely triggered on steep slopes in open trees where they present as preserved surface hoar.
In the north of the region, the lower snowpack remains weak and heavily faceted.
Weather Summary
Sunday night
Clouds and snowfall, 5 to 15 cm of accumulation. Alpine temperatures -10 °C. Ridgetop wind southwest 80 km/h gusting to 100 km/h. Freezing level 300 m.
Monday
Cloudy with snowfall, 1 to 3 cm of accumulation. Alpine temperatures reach a high of -4 °C. Ridge wind southwest 60 km/h gusting to 100 km/h. Freezing level 1200 m.
TuesdayCloudy no new precipitation, ridgetop wind northwest 60 km/h gusting to 100 km/h, alpine temperature 1°C. freezing level 1500 m.
WednesdayCloudy no new precipitation, ridgetop wind northwest 80 km/h, alpine temperature 1°C. freezing level 1500 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.
- Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
- Be aware of the potential for surprisingly large avalanches due to deeply buried weak layers.
Avalanche Problems
Wind Slabs
Continuing southerly winds and new snow will form fresh wind slabs in alpine and treeline lee aspect terrain. Watch for changing conditions with aspect and elevation and avoid wind-loaded areas.
New weak cornice growth is a concern, it's very likely that even a small cornice collapse will initiate the building wind slab below.
Aspects: North, North East, East, South East, West, North West.
Elevations: Alpine, Treeline.
Likelihood: Likely - Very Likely
Expected Size: 1 - 2.5
Persistent Slabs
Triggering persistent slab avalanches remains possible due to several weak layers in the top metre of the snowpack. Facet layers are the primary concern in alpine terrain, while preserved surface hoar layers are the concern in treeline terrain.
In the north of the region, the lower snowpack remains weak and heavily faceted. Large triggers such as cornice failure or smaller avalanches stepping down to this layer are possible.
Avalanches that start as wind slabs may step down to these deeper layers.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1.5 - 3