Sea To Sky

A buried weak layer is capable of producing large human-triggered avalanches. Stick to small supported terrain features and be cautious when slopes are getting hit by direct sunlight.

Moderate - Intensity of incoming weather systems is uncertain on Thursday

WEDNESDAY: Sunny in the morning with increasing clouds in the afternoon, light southwest wind, freezing level rising to around 1400 m.THURSDAY: Flurries increasing throughout the day with 5-10 cm of snow by the afternoon, moderate southwest wind, freezing level rising to around 1200 m.FRIDAY: Another 5-10 cm of snow with freezing level rising to around 1200 m.

No notable avalanches were reported on Monday, but reports from the weekend highlight a touchy persistent slab problem in this region.Numerous reports of whumpfing around upper treeline elevations were reported, as well as a few large avalanches. An MCR report from the Blackcomb backcountry on Sunday describes a size 3 avalanche that was remotely triggered on a west aspect around 1900 m and presumably failed on the buried surface hoar layer (see photo and details here). A size 2 slab avalanche failed in a north-facing chute at a similar elevation and triggered additional smaller avalanches on nearby slopes. Closer to Squamish, a natural size 2 avalanche failed on a south aspect at 1750 m (see photo and details here). These avalanches highlight a persistent slab problem that exists on all aspects around treeline elevations. This type of problem tends to take a while to heal, and avalanches could remain reactive to human triggers throughout the week.

A thin sun crust has formed on solar aspects and the surface is wind affected in most exposed terrain. Last week's storms buried a weak layer composed of soft facets, surface hoar, and/or crust that is roughly 50-100 cm below the surface. This layer has produced whumpfing, sudden results in snowpack tests, and some remotely triggered avalanches. Lots of the activity has been on buried surface hoar on north aspects at upper treeline elevations. The snowpack is well settled and strong beneath this interface. Variable winds in the past month have produced cornices on many ridgelines. They will become touchier as they grow in size, as temperatures rise, and when they are subject to the strong late-winter sun on clear days.