It's a good day to make conservative choices.
Stick to low-angle below treeline slopes, with no overhead hazard from big avalanche terrain.
This weak layer has demonstrated extensive propagation across terrain features following the last big storm. With the incoming weather, it has the potential to trigger very large natural and human-initiated avalanches again.
New snow and strong west winds are expected to build reactive new storm slabs. The highest danger will be on steep, leeward slopes below ridgetops.
On Monday, north of Stewart, a vehicle triggered a size 1.5 slab on the persistent weak layer. It failed on a northwest slope in the alpine. A few wind slabs size 1 to 2 were also observed across the region.
We expect a widespread natural avalanche cycle to be ongoing, and to continue overnight and into Wednesday. The potential for human-triggered avalanches is expected to be almost certain during this stormy period.
15 to 30 cm of snow fell throughout the day Tuesday. An additional 10 to 20 cm accompanied by moderate to strong westerly ridgetop winds is forecast to fall overnight. This combination is expected to form fresh storm slabs and deep wind-deposits on leeward slopes.
We expect the accumulated storm slabs to be especially touchy wherethey are sitting on a layer of buried surface hoar, facets, or a thin crust, in some areas.
A persistent weak layer of surface hoar and facets overlying a crust. It is buried 60 to 120 cm deep in the southern parts of the region, and up to 200 cm deep in areas north of Stewart.
The snow surface may be moist, wet or crusty below 1100m.
Tuesday Night
Cloudy with 10 to 20 cm of snow near Terrace, 0 to 5 cm near Stewart. 40 km/h west ridgetop wind. Treeline temperature -2 °C. Freezing level ~ 1100m.
Wednesday
Cloudy, with 0 to 3 cm of snow. 35 to 45 km/h west ridgetop wind. Treeline temperature -2°C. Freezing level ~ 1100m.
Thursday
Cloudy with 15 to 25 cm of snow. 80 to 100 km/h south ridgetop wind. Treeline temperature -1 °C. Freezing level rising to ~1400 m near Terrace.
Friday
Cloudy with 2 to 10 cm of snow. 50 km/h southwest ridgetop wind. Treeline temperature -3 °C. Freezing level rising to ~1000 m.
More details can be found in the Mountain Weather Forecast.
