Avalanche Forecast

High -

Tuesday night: Clear. Light northwest wind. Freezing level valley bottom.

Wednesday: Sunny. Light north wind. Freezing level 1000 m.

Thursday: Sunny. West wind increasing to moderate. Freezing level 1200 m.

Friday: Mix of sun and cloud. Moderate west wind, strong at ridgetop. Freezing level 1300 m.

Natural size 2 persistent slab avalanche on the February rain crust was observed Monday and Tuesday. Explosive and skier control work on Sunday produced size 1.5-2 storm slabs, and size 1 loose dry. Solar triggered loose dry avalanches to size 1.5 were also observed in steep south facing terrain.

Reports have been trickling in of deep persistent avalanches on deep weaknesses near the bottom of the snowpack. The most recent is described in this MIN report from February 11. There was also a bigger avalanche reported in this MIN on February 9th (check out the photos, they're humbling). The very large avalanche ran on a north facing feature at 2400 m and was triggered by a snowmobile. 10 or so climbs had been made without incident in the same area in the days leading up to this avalanche. Activity on these layers often accompany abrupt changes in weather.

Previous winds have redistributed recent snow into wind slabs in the alpine and exposed areas at treeline. 

A thick rain crust from early February sits 20-70 cm below the surface up to 2100 m. Recent reports indicate that faceting may be occurring at the interface of this crust and overlying snow in some areas, creating a weak layer between a slab and a slick bed surface. At least one avalanche was reported to have slid on this layer on Monday.

A well consolidated mid-pack overlies generally weak basal facets that may be possible to trigger in isolated shallow rocky start zones or with large loads. There is some uncertainty about whether the forecast sunny period will provide a strong enough input to resurrect this avalanche problem. 

• Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet
• A moist or wet snow surface, pinwheeling and natural avalanches are all indicators of a weakening snowpack.
• Caution around slopes that are exposed to cornices overhead.
• Be careful as you transition into wind affected terrain.
• Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.