Continue to make conservative terrain choices while the storm snow settles and bonds to underlying layers
Careful route selection and avoiding overhead hazard is recommended
While the likelihood of triggering a persistent slab has dropped following the storm, the consequences remain very serious.
Storm slabs have shown wide propagation where they sit over weak surface hoar crystals. Potential remains for storm slabs to step-down down to deeper persistent weak layers.
Numerous large and very large storm slabs up to size 3, occurred across the region over the last few days of stormy weather. Notably, only a few cases failed on the persistent weak layer.
Skiers have also reported widespread whumpfing and shooting cracks.
Looking forward, we expect natural avalanche activity to taper off, but for human triggering to remain likely at upper elevations.
40 to 80 cm of recent storm snow has accumulated in the alpine, and is now settling rapidly with the mild temperatures. Some of this new snow fell as rain, with the rain/snow line around 900 -1200 m. A crust or wet snow may exist below those elevations.
The storm snow may be slow to bond because it sits on surface hoar, facets, or a thin crust.
Strong winds from various directions have been redistributing the new snow, building deeper and more reactive deposits on lee slopes.
A persistent weak layer of surface hoar and facets overlying a crust is buried 90 to 140 cm deep in the southern parts of the region, and up to 240 cm deep in areas north of Stewart. Avalanches failing on this layer will be very large and destructive.
Saturday Night
Cloudy with 0 to 3 cm of snow. 50 km/h west ridgetop wind. Treeline temperature -2 °C.
Sunday
Partly cloudy. 25 to 35 km/h west ridgetop wind. Treeline temperature -2 °C.
Monday
Cloudy with 5 to 15 cm of snow. 55 km/h southwest ridgetop wind. Treeline temperature -1 °C.
Tuesday
Cloudy with 20 to 40 cm of snow. 80 km/h southwest ridgetop wind. Treeline temperature 0 °C. Freezing level 1300 m.
More details can be found in the Mountain Weather Forecast.
