Use extra caution at treeline where triggering the current persistent weak layer is most likely.
Recent snow sits over a facet-crust weak layer combination that is possible to human trigger. This problem is particularly concerning in the north of the region. Recent observations demonstrate the potential for this problem to be triggered remotely and release sympathetic avalanches in adjacent terrain.
New wind and storm slabs will form throughout the day on Friday. Sensitivity to triggering will be greatest on wind loaded features on north and east aspects. Strong winds mean that wind slab could be found further down slope than expected.
Thursday night: light snowfall and moderate west winds. Low of -4 at 1500m.
Friday: stormy with up to 25cm of snow. Strong southwest winds with extreme gusts. Freezing levels rising to 1300m.
Saturday: some light flurries with light to moderate northwest winds. High of -2 at 1500m.
Sunday: clear skies and no new snow expected. Light to moderate southwest winds. Freezing level rising to 1400m.
On Tuesday in the north of the region one skier remote size one was reported. This avalanche was on a northeast aspect at 1700m and is believed to have failed on the surface hoar and facet layer down 30cm from late January.
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 a 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 late January 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).
New snow accompanied by strong southwest winds will form new storm and wind slabs at all elevations. Wind slabs will likely be found on north and east aspects.
15 to 40cm sits above a variety of surfaces including surface hoar, facets and a crust. This layer is most prominent at treeline and above. Especially in the Duffy area.
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.
