Avalanche Forecast

Sunday night: Partly cloudy, light southwest winds with strong west winds over the divide, no precipitation, freezing level at valley bottom.

Monday: Mix of sun and cloud, moderate southwest winds with strong to extreme west winds over the divide, no precipitation, alpine high temperature reaching -2 C, freezing level rising to 1500 m by end of day and a weak inversion setting up overnight. 

Tuesday: Increasing cloud, a short-lived overnight inversion is forecast to break down by morning, moderate southwest winds with strong west winds over the divide becoming northwest, isolated light flurries with trace accumulations, alpine high temperature reaching 0 C, freezing level around 1600 m. 

Wednesday: Mostly cloudy, light southwest winds, 5-15 cm of snow, alpine high temperature reaching -1 C, freezing level near valley bottom.

At the beginning of last week's strong temperature inversion, small (up to size 1.5) loose wet avalanches were observed on steep solar slopes and in extreme rocky terrain.

There have been no reports of large avalanches in the past week. The most recent wind slab avalanche activity was reported at the end of November. 

Over the weekend, observers reported widespread surface hoar growth (feather-like frost crystals). Check out these great photos (here, here, and here) from our close neighbors in the Lizard/Flathead region. The formation and distribution of the surface hoar will be important to track ahead of the next snowfall. We appreciate the recent reports submitted to the Mountain Information Network. Keep them coming! 

After several days of clear skies and warm air in the alpine, temperatures are returning to their seasonal normal, and melt-freeze crusts have been left behind on solar aspects. Strong southwest winds previously scoured upwind slopes and ridges and deposited snow into stiff wind slabs on lee or cross-loaded features. These old wind slabs may sit above a widespread rain crust from early November, which can be found up to 2500m and buried down 30-100cm. Weak snow may be developing around this crust. However, given the stagnant weather pattern and decreasing trend in instability, this problematic snowpack structure is not currently listed as a problem. We can expect to see it transition to our problems page with the next snowfall. It will be a feature to monitor as the season progresses.

The snowpack is thin and variable in wind-scoured areas and tapers rapidly at lower elevations. Snowpack depths at sheltered upper treeline elevations are nearing 100 cm and beginning to exceed the threshold for avalanches. 

• Small avalanches can have serious consequences in extreme terrain. Carefully evaluate your line for wind slab hazard before you commit to it.