Avalanche Forecast

The cooling and drying trend continues with overcast conditions throughout Thursday and some sunshine Friday/ Saturday. Alpine temperatures will remain cool at -5 and freezing levels will likely be near 500 m. Ridgetop winds will blow strong tomorrow from the East then switch to the northeast and decrease to light values for Friday and Saturday.

On Wednesday, human and explosive triggers saw up to size 1 running within the recent storm snow.

On Tuesday, a widespread natural avalanche cycle and to size 3 and reports of a size 4 in the Bear Pass area. These larger slab avalanches are said to be mostly storm instabilities with some active persistent slab avalanches. As conditions start to get cooler and dryer the natural avalanche activity will likely decrease, however; uncertainty sits with the persistent slab problem which should remain on your radar.

Have you been out riding in the mountains? We would love to hear about it and it doesn't need to be technical! Photos can be extremely helpful; please share your observations on the Mountain Information Network (MIN). Thanks!!

The recent storm brought over a metre of snow accompanied by strong southwest winds to alpine elevations. Treeline elevations saw quite the mix of snow and rain depending on where the freezing level sat (mostly around 1200 m during the storm). Below treeline the snowpack became saturated with rain. Cornices have likely grown large along ridgelines at upper elevations and pose threat to the slopes below. All and all, this storm provided new load and stress to the existing snowpack and a widespread avalanche cycle was the response. The current cooling and drying trend will likely start to lock-up and stabilize the snowpack. However; deeper instabilities may still exist at treeline and above elevations. The early December crust is now down 100 cm plus in the alpine and just below the surface at treeline. The early November crust is even deeper in the alpine and down 70-120 cm at treeline. Basal facets exist and have produced large full depth avalanches pre-storm and during the storm. The extent of this problematic snowpack structure in the region is not well-known, but it likely exists in colder, shallower snowpack areas. These interfaces have shown recent reactivity and the major questions are moving forward. How is the snowpack adjusting with the cooling and are these interfaces still reactive and critical layers? A bit more time and hopefully more data will tell.

Snowpack depths are highly variable across aspects and elevations as a product of wind scouring, above-freezing temperatures, and rain. Snow has melted fast at lower elevations, and snowpack depths have seen rapid settlement.

• Keep in mind that human triggering potential persists as natural avalanching tapers off.
• Storm slabs in motion may step down to deeper layers resulting in large avalanches.
• Recent wind has varied in direction so watch for wind slabs on all aspects.
• Be alert to conditions that change with elevation.