Watch for ongoing wind slab formation throughout the day.
A weak layer from early December may become more reactive with the incoming snowfall and wind, and persistent slabs are possible.
Watch for new wind slab development in exposed terrain on Wednesday.
Wind slabs have the potential to step down to a weak layer from early December resulting in larger than expected avalanches.
A weak layer from early December appears to be most reactive in the deeper snowpack areas including the Dogtooth and western Purcells. This layer may become increasingly reactive on Wednesday with loading from new snow and wind.
In the Invermere area, weak faceted snow at the base of the snowpack remains a concern. Avalanches have occurred on steep, smooth north-facing slopes where the snowpack is shallow and weak.
On Tuesday, a ski cut triggered a size 1 persistent slab avalanche at 2300 m in a deeper snowpack area near the Purcell Wilderness Conservancy. This failed on the early December surface hoar down 40 cm.
On Monday, a natural size 2 avalanche was reported on an east aspect at 2300 m near Bugaboo Provincial Park. In the Dogtooth, explosives triggered a size 1 avalanche on a north aspect in the alpine which is expected to have failed on the early December weak layer.
New snowfall will continue to add to the 5-15 cm of snowfall which has accumulated since Sunday. Wind will continue to redistribute this snow in exposed terrain.
A weak layer from early December may include surface hoar and/or small facets on shaded slopes, and a sun crust on south slopes. In the Dogtooth and western Purcells, this layer is down around 40 cm and has been reactive recently. In the shallower snowpack areas around Invermere, the layer is only down 10-20 cm.
Around Invermere, the base of the snowpack consists of weak, faceted snow over a crust from late October. This layer likely exists throughout the region but has recently only been reactive in shallow snowpack areas around the Invermere.
Tuesday Night
Cloudy with 4-8 cm of snow. 20-40 km/h southwest ridgetop wind. Treeline temperature -8 °C.
Wednesday
Cloudy with 8-12 cm of snow in the morning, and possible sunny breaks in the afternoon. 20-50 km/h southwest ridgetop wind. Treeline temperature -4 °C.
Thursday
Mostly sunny. 10-20 km/h southwest ridgetop wind. Treeline temperature -5 °C.
Friday
A mix of sun and cloud. 10-20 km/h southwest ridgetop wind. Treeline temperature -2 °C.
More details can be found in the Mountain Weather Forecast.
