Despite the recent warm and wet conditions at lower elevations, snow has likely been accumulating at higher elevations, accompanied by strong westerly winds.
At higher elevations, where recent precipitation has fallen as snow, not rain, widespread wind slab formation has occurred.
A crust buried deep in the snowpack has proven reactive to large loads, particularly in steep, exposed terrain. A small wind slab avalanche triggered above may be enough of a load to step down to this deeper layer.
A few large (size 2 to 3) avalanches occurred on Tuesday. These avalanches were initiated by very large triggers, such as explosives or snowcats, and failed approximately 50 to 150 cm deep on the November crust described in the snowpack summary.
While natural avalanche activity is not expected on Thursday with cooling temperatures, rider-triggered avalanches may remain likely.
Recent warm, wet, and windy conditions will result in heavy, wet snow or a surface crust, depending on elevation and region, by Thursday morning. Pockets of dry, wind-affected snow exist in alpine terrain.
A mid-November crust sits 50 to 100 cm deep. Below it, the snowpack contains multiple crusts, and in some areas, a weak, sugary facet layer exists near the ground.
Treeline snowpack depths range from roughly 50 to 100 cm, thinning quickly at lower elevations. In many areas, especially below treeline, slopes lack enough snow to cover ground roughness and produce avalanches.
Wednesday Night
Cloudy. 25 to 35 mm of precipitation as snow or rain at treeline. 60 km/h southwest ridgetop wind. Treeline temperature 0 °C. Freezing level 1800 m.
Thursday
Cloudy. 3 cm of snow. 50 km/h west ridgetop wind. Treeline temperature -2 °C. Freezing level 1300 m.
Friday
Cloudy. 4 to 5 cm of snow. 40 km/h west ridgetop wind. Treeline temperature -5 °C.
Saturday
Mostly cloudy. 1 to 2 mm of precipitation as snow or rain at treeline. 50 km/h west ridgetop wind. Treeline temperature 0 °C. Freezing level 2000 m.
More details can be found in the Mountain Weather Forecast.
