The incoming storm is driving the avalanche danger. Reactive storm slabs will build throughout the day.
It's time to step back. Check out the new Forecaster Blog "Shifting your Mindset"
The new snow will have a poor bond to the underlying snow surfaces and human triggering is likely. Northeast aspects will likely see deeper slabs with wind loading.
Dry loose avalanches are likely from steep terrain features.
On Wednesday, a natural cornice fall (size 2.5) was reported. It was a couple of days old and scrubbed to the ground. It did not propagate the slope below.
With new snow and strong wind forecast, natural and human-triggered avalanches are likely on Friday.
Up to 20 cm of snow is expected to fall by Friday afternoon. The new snow will likley have a poor bond to the plethora of old snow surfaces. These consist of a melt-freeze crust on previously sun-exposed slopes, surface hoar and/or facets on shaded slopes, and wind-affected surfaces in exposed terrain at higher elevations.
A layer of facets and/or surface hoar buried in early December may be found down 50-100 cm, or as shallow as 30 cm around Invermere. Recently this layer has not been a significant problem but should be kept on your radar with additional load from new snow and wind.
The base of the snowpack consists of a thick crust and facets or depth hoar in many areas.
Thursday Night
Cloudy with snow 5 to 10 cm. 15 to 40 km/h southwest ridgetop wind. Treeline temperature -10 °C.
Friday
Cloudy with snow 5 to 8 cm. 15 gusting to 45 km/h southwest ridgetop wind. Treeline temperature -2 °C. Freezing level 1100 m.
Saturday
Cloudy with sunny periods and isolated flurries. 15 gusting to 40 km/h southwest ridgetop wind. Treeline temperature -10 °C.
Sunday
Cloudy with sunny periods and isolated flurries. 20 km/h southwest ridgetop wind. Treeline temperature -15 °C.
More details can be found in the Mountain Weather Forecast.
