Dangerous avalanche conditions exist where reactive wind slabs remain possible to human-trigger.
Evaluate terrain features on an individual basis before committing to them.
Recent snow and extreme winds built stubborn wind slabs in lee features at treeline and in the alpine. Wind slabs may be poorly bonded to the underlying crust. Human-triggering wind slabs remains possible.
A weak layer of facets or surface hoar above a thick crust persists in the snowpack. If triggered wind slab avalanches may step down to this layer to create a larger, more destructive avalanche.
On Monday, explosives control in the area produced several wind slab avalanches, up to size 1.5, in lee alpine features.
On a Saturday, a size 2, skier accidental wind slab avalanche was reported on a southeast-facing alpine slope on the Spearhead Traverse. The group was boot-packing up the slope when they triggered the 20 cm deep slab
5 to 15 cm of storm snow and previous extreme southerly winds have built stubborn wind slabs in exposed lee features at higher elevations. Recent snow overlies a variety of surfaces, including a crust on south facing slopes and low elevations, and faceted snow and/or small surface hoar in sheltered terrain.
20 to 60 cm down is a layer of facets and areas of isolated surface hoar above a thick crust. This layer has produced concerning results in recent snowpack tests and is most concerning at treeline and above.
Monday Night
Mainly clear skies. 25 to 40 km/h northwest ridgetop wind. Treeline temperature -13 °C. Freezing levels remain at valley bottom.
Tuesday
Increasing clouds. 25 to 40 km/h northwest ridgetop wind. Treeline temperature -11 °C. Freezing levels remain at valley bottom.
Wednesday
Cloudy with 20 to 40 cm of snow. 40 to 60 km/h southwest ridgetop wind. Treeline temperature rises to -3 °C. Freezing level rises to 1300 m throughout the day.
Thursday
Mainly cloudy with 1 to 5 cm of snow. 10 to 25 km/h southwest ridgetop wind. Treeline temperature rises to -3 °C. Freezing level hovers around 800 m.
More details can be found in the Mountain Weather Forecast.
