Wind slabs are likely reactive to human-triggering.
Sun can quickly change snow conditions. Avoid steep slopes if the snow is moist, and stay well clear of cornices.
New snow and moderate northwest wind are building wind slabs at upper elevations. Wind slabs are likely to be more reactive where they are building of old hard surfaces like crusts and wind-pressed snow.
Persistent weak layers of crust/facets or surface hoar are buried in the upper 250 cm of the snowpack. Distribution seems spotty and signs of instability may not be evident. The best defence is choosing smaller, low-consequence terrain.
Even brief periods of sun will be enough to trigger wet loose avalanches in steep terrain features. The impact might be dampened by moderate wind and cool temperatures.
On Tuesday, a human remotely triggered a wind slab (size 1). This was on a southeast slope at treeline around 1600 m. It ran on a buried suncrust. Numerous reports from Monday's avalanche cycle continue to see slab avalanches up to size 2.5.
On Monday, a widespread natural avalanche cycle of storm slab and wind slabs were reported across the region. Sizes were generally size 2 to 2.5. Numerous wet loose avalanches were also reported up to size 2.
Recent storm snow is being redistributed by moderate northwest winds, forming wind slabs in lee terrain features at upper elevations.
Below this, there are several old surfaces depending on aspect and elevation: A sun crust on solar aspects. Faceted snow and/or buried surface hoar in sheltered northerly aspects and firm wind-pressed snow.
Several persistent weak layers are buried up to 250 cm deep. While triggering these layers is becoming unlikely, they present a low-probability, high-consequence problem.
Wednesday Night
Clear skies. 20 km/h northwest ridgetop wind. Treeline temperature -2 °C.
Thursday
Sunny. 20 km/h northwest ridgetop wind. Treeline temperature -1 °C.
Friday
Mix of sun and clouds. 10 km/h south ridgetop wind. Treeline temperature 2 °C. Freezing level 1200 m.
Saturday
Sunny. 10 km/h south ridgetop wind. Treeline temperature 4 °C. Freezing level 1500 m.
More details can be found in the Mountain Weather Forecast.
