A deeply buried weak layer continues to produce large avalanches, and a conservative mindset is recommended.
Watch for fresh wind slabs on Thursday.
New snow with strong wind on Wednesday and Thursday is expected to form new wind slabs in exposed terrain. Older wind slabs from Sunday and Monday may also still be reactive to human triggering.
A weak layer of facets and a crust down 80 to 140 cm has produced several very large avalanches over the past week. Remotely triggered avalanches and wide propagations remain possible.
On Tuesday and Wednesday, two natural cornice-triggered size 3 slab avalanches occurred in steep terrain. At least one of these failed on the early-Dec weak layer. An older natural size 3 slab avalanche was also observed above Bryant Lake (MIN report).
On Tuesday, the field team observed two older size 2 wind slabs from the highway and an old snowmobile triggered size 2 in the Fraser Chutes.
Last week, a remotely triggered size 3 persistent slab occurred (MIN report).
Around 10 cm of new snow on Wednesday adds to the 30-50 cm of settling storm snow from the last week which can be found in sheltered terrain. Exposed terrain has been heavily wind-affected.
A weak layer of facets and a crust from early December is buried 80 to 140 cm deep. This layer exists on all aspects up to around 1700 m. This layer has shown recent reactivity, and we expect it to remain sensitive to heavy triggers and human triggering in shallow snowpack areas.
Check out this recent ACMG Mountain Conditions Report for more on the persistent weak layer problem.
Wednesday Night
Cloudy with snowfall 5-15 cm. 30 to 50 km/h southwest ridgetop wind. Treeline temperature -5 °C.
Thursday
Mostly cloudy with flurries. 30 to 50 km/h west ridgetop wind. Treeline temperature -4 °C.
Friday
A mix of sun and cloud. 40 to 60 km/h west ridgetop wind. Treeline temperature -3 °C.
Saturday
Cloudy with sunny breaks. 40 to 60 km/h west ridgetop wind. Treeline temperature -3 °C.
More details can be found in the Mountain Weather Forecast.
