Avalanche Forecast

Tuesday: Partly cloudy, light northwest winds, treeline low temperatures near -14 C.

Wednesday: Cloudy, isolated flurries with a trace of snow, moderate southwest winds increasing to strong and becoming west at upper elevations, treeline high temperatures near -11 C.

Thursday: Cloudy, isolated flurries with a trace of snow, moderate west winds, treeline high temperatures rising to -6 C in the late afternoon, freezing level rising to 600 m. 

Friday: Cloudy, 5-10 cm of snow, strong southwest winds with extreme gusts, treeline high temperatures near -4 C, freezing level rising to 1400 m. 

It may be possible to trigger large avalanches in specific terrain on Wednesday. Cornices could be reaching their breaking point and could act as triggers on slopes below.

On Tuesday, there was a report of a small (size 1) human-triggered avalanche that released in the recent snow on a convex feature at upper treeline elevations near Pemberton. 

In the neighbouring Sea to Sky region, we received report of a large (size 2.5) human-triggered avalanche near Rainbow Mountain that caught and carried a group of five skiers. The avalanche released on north aspect at 1900 m. It broke 40 cm deep on the facet-crust layer. The avalanche propagated across adjacent roll-over features and triggered a sympathetic slide on a small feature 200 m away.

On Sunday, observers in the north of the region reported large (size 2) natural avalanches releasing in the storm snow near Dark Side Lake (see this MIN and this MIN). In the south of the region, operators reported several small (size 1) dry loose avalanches releasing naturally in steep, rocky terrain. 

Over the weekend, the mountains picked up 15-30 cm that fell as snow above 1400 m along the Duffey and above 1700 m near the Coquihalla. Strong to extreme southwest winds during the storm have since become moderate from the northwest and have redistributed the recent snow into wind slabs across a range of aspects at upper elevations. Monitor for changing slab conditions as you move into wind-exposed terrain.

Recent snow rests on a problematic layer combination. Weak sugary facets formed during a prolonged dry period over a thick melt-freeze crust. In sheltered areas at upper elevations, surface hoar may also be found on the crust. This late January facet-crust layer has demonstrated continuing reactivity in the aftermath of the weekend storm, particularly in areas north in the region. In the south of the region, this layer combination may be present at upper elevations in features where the facets were preserved. Travellers have reported remote-triggered avalanche activity and widespread whumpfing on this layer (see this MIN report and this MIN report from Joffre Peak).

Deeper in the snowpack, it is possible to find a crust/facet layer from December that is buried down 100-150 cm. This layer is most prominent between 1700-2100 m and is currently classified as dormant; although large loads such as a cornice failure or avalanches in motion may still be able to trigger avalanches on this layer.

• Recent wind has varied in direction so watch for wind slabs on all aspects.
• Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
• Be aware of the potential for large avalanches due to the presence of buried weak layers.
• Remote triggering is a concern, avoid terrain where triggering slopes from below is possible
• Extra caution is needed around cornices under the current conditions.