Alpine and Treeline danger has been updated to HIGH in response to higher than anticipated snow amounts. It's a good time to avoid exposure to avalanche terrain.
Confidence
Low - Intensity of incoming weather systems is uncertain
Weather Forecast
Tuesday:15-20 cm wet new snow. Winds strong southerly in the morning, diminishing to light westerly by the afternoon. Freezing level around 1200 m, lowering later in the day.Wednesday: Rain and snow starting around noon, with 20+ mm possible by the end of the day. Freezing level around 1200 m. Winds strong southwesterly.Thursday: Continued snow in the morning, tapering off in the afternoon. Freezing level dropping to around 900 m. Winds strong southwesterly.
Avalanche Summary
During Tuesday's storm, avalanche activity will be dependent on how much of the expected precipitation falls as snow (as opposed to rain). If we get 20 cm of wet snow, I'd expect avalanche activity to be confined to steep slopes behind ridges where it is wind effected. If amounts are higher and the snow is colder, more widespread activity is possible.
Snowpack Summary
Recent heavy rainfall saturated the snowpack at all elevations and washed away much of the snow at lower elevations. Expect to find a crust buried under a skiff of new snow, which fell right at the end of the storm as temperatures fell. Travel in many places is rugged, with many open creeks and early season hazards. There's currently about 5 cm snow at 900 m and around 100 cm at 1200 m.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.