Avalanche Forecast

Moderate - Intensity of incoming weather systems is uncertain

The ridge of high pressure will be displaced by a low pressure system late Monday. A mix of sun and cloud is expected Monday morning and cloudy conditions with light flurries are expected for the afternoon. Alpine wind should be light in the morning and increase to strong during the afternoon. Treeline temperatures are expected to be around -12C. Around 10 cm of snow is expected on Monday night with strong alpine wind from the southwest. Another 5-10 cm of snow is forecast for Tuesday with moderate to strong alpine wind from the southwest and treeline temperatures around -10C. A mix of sun and cloud is currently forecast for Wednesday.

On Saturday, a natural size 3 avalanche was reported in the east Selkirks on a southeast aspect at 3000 m elevation. On Friday and Saturday, a few natural size 2-2.5 wind slab avalanches were observed in Glacier National Park in steep terrain features on north and northwest aspects at 2500-2700 m elevation. On Friday, a skier triggered a size 1 storm slab avalanche on a northwest at 1800 m elevation in the east Selkirks. This was a 40 cm thick slab which failed on the mid-December interface. On Monday, it is possible that new wind slabs may develop in the afternoon as the wind increases. Old stubborn wind slabs may still be lingering from the strong wind that ended Friday morning and could be hiding under 10-20 cm of low density snow from Saturday. In the eastern Selkirks, the mid-December interface may be more reactive than the rest of the region where it is now considered dormant.

40-70 cm of snow has accumulated over the last week and overlies the mid-December interface which consists of a variety of old snow surfaces including wind affected snow, faceted (sugary) crystals, and/or surface hoar crystals. Recent tests suggest the the new snow is well bonded to the interface in most areas. However, where a spotty layer of surface hoar has been preserved, the interface is still reactive to snowpack tests. In wind affected terrain, the recent storm snow has been redistributed into reactive wind slabs. These wind slabs may now be buried under 10-20 cm of low density snow which fell without much wind on Saturday.The thick mid-November crust layer typically sits 1-2 m down in the snowpack. Recent test results on this layer suggest it is generally well bonded to the adjacent snow with the possible exception of shallow snowpack areas. This layer is considered dormant at this time but remains an isolated concern that we will likely be tracking through much of the season.