Avalanche conditions will deteriorate over the next two days as temperatures rise. There is potential for large, destructive natural avalanches on buried weak layers to run far.
Recent snow and wind have formed wind slabs in leeward terrain features at upper elevations. If triggered, these avalanches can step down to buried weak layers, resulting in large, destructive avalanches.
Several buried weak layers exist throughout the snowpack. These layers will likely become increasingly active in the coming days as the snowpack warms and weakens.
There is evidence that weak layers near the bottom of the snowpack are starting to wake up. Avalanches on these layers will be large, destructive and may run full path.
On Friday and Saturday, natural wind slab avalanches up to size 2 were reported near Invermere, including one which stepped down to a persistent weak layer. Last week, numerous persistent slab avalanches were reported in the central Purcells, including remote triggers from 60 m away.
Looking forward, we can expect to see more large persistent slab avalanches over the next couple of days as temperatures spike.
Recent snow may be wind affected at upper elevations while moist surfaces exist below 2000 m. Below, lies a complex snowpack.
An interface from early March, 30 to 50 cm deep, consists of a crust on sunny slopes and lower elevations, and surface hoar or facets in sheltered, shaded upper elevations.
Persistent weak layers from February and January, including crusts, facets, and surface hoar, are buried 50 to 100 cm deep and remain a concern.
The bottom of the snowpack is composed of large facets, which are becoming reactive again, with some very large avalanches recently failing on this layer.
Monday night
Cloudy with a trace of snow. 10 to 20 km/h west ridgetop winds. Treeline temperature 0 °C. Freezing level 2000 m.
Tuesday
Cloudy with light rain. 10 to 20 km/h southwest ridgetop winds. Treeline temperature +4 °C. Freezing level rising to 2500 m.
Wednesday
Sunny. 10 to 20 km/h southeast ridgetop winds. Treeline temperature +6 °C. Freezing level rising to 3000 m.
Thursday
Cloudy with 3 to 8 cm of snow. 20 to 30 km/h southwest ridgetop winds. Treeline temperature 0 °C. Freezing level falling to 2000 m.
More details can be found in the Mountain Weather Forecast.
