The snowpack remains sensitive to 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.
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.
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.
Sunday: A remotely triggered avalanche was reported by skiers near the 4 lakes in the Babine mountains provincial park. This avalanche was a small (size 1.5) slab avalanche and was initiated while traveling from below. See the embedded MIN for pictures and details.
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.
Strong southerly wind and light snowfall are expected to continue the formation of fresh wind slabs and build 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.
At upper elevations, southerly winds continue to scour windward areas and redistributed past and current storm snow into wind slabs in lee areas. Wind slab depth has been reported as up to 50 cm in depth and is likely to be much bigger given this information Is greater than 48 hours old.
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-depth snowpack remains weak and heavily faceted.
Monday night
Cloudy with light snowfall, 1 to 3 cm of accumulation. Alpine temperatures reach a high of -4 °C. Ridge wind southwest 60 km/h. Freezing level 500 m.
Tuesday
Cloudy with light snowfall, 1 to 3 cm of accumulation. Alpine temperatures reach a high of -2 °C. Ridge wind southwest 60 km/h gusting to 80 km/h. The freezing level will rise to 700 m.
WednesdayCloudy with light snowfall, 1 to 3 cm of accumulation. Alpine temperatures reach a high of 0 °C. Ridge wind west 60 km/h gusting to 100 km/h. The freezing level will rise to 1500 m.
ThursdayCloudy with very light snowfall, and trace amounts of accumulation. Alpine temperatures reach a high of -2 °C. Ridge wind west 80 km/h. The freezing level will descend to 1000 m.
More details can be found in the Mountain Weather Forecast.
