Welcome to the first forecast of the season! Wind slabs at higher elevation may be possible to trigger on Thursday. Those in the north of the region should also assess for a potential weak layer near the base of the snowpack.
Around 15 to 20 cm of snow from Tuesday's storm has likely been redistributed by strong southerly wind in exposed terrain. Expect to find deeper deposits in lee terrain features near ridges.
In the north of the region (e.g., Duffey Lake), there is potential to trigger a weak layer of sugary faceted grains around a hard melt-freeze crust near the base of the snowpack. The last skier-triggered avalanche on this layer was from the weekend. The most likely terrain features of concern are where the ground cover is smooth, such as on scree slopes, rock slabs, or glacial ice.
WEDNESDAY NIGHT: Cloudy with isolated flurries, accumulation trace to 3 cm, light northwest wind, alpine temperature -6 C.
THURSDAY: Cloudy with afternoon snowfall, accumulation 1 to 3 cm, light to moderate southwest wind, alpine temperature -5 C.
FRIDAY: Cloudy with snowfall, accumulation 5 cm, moderate to strong southwest wind, alpine temperature -3 C, freezing level 1400 m.
SATURDAY: Early-morning snowfall then clearing, accumulation 10 cm, moderate west wind, alpine temperature -5 C.
Large (size 2) storm slab avalanches were triggered naturally and by explosives on Wednesday near Duffey Lake. They occurred on northerly aspects in alpine terrain.
The most recent report of an avalanche on the early-November layer was from November 21 near Duffey Lake. Check out this MIN for a photo.
Our eyes and ears in the mountains are limited at this time of year and may continue this winter due to fewer professional observations. If you see anything while out in the field, please consider sharing it with us and fellow recreationists via the Mountain Information Network (MIN). Even just a photo of where you went is helpful. A big thank you to those that have already shared their observations thus far.
Expect to find a treeline snowpack depth of around 100 to 150 cm in the south of the region and 80 to 120 cm in the north of the region.
About 15 to 20 cm of snow from Tuesday's storm may have been redistributed by southwest wind, forming deeper and cohesive deposits in lee terrain features at higher elevations.
A melt-freeze crusts from mid-November is generally found 50 cm below the snow surface. Many reports suggest the upper snowpack is well-bonded to this crust. Spotty layers of weak surface hoar crystals may be found in the middle of the snowpack (50 to 100 cm deep), particularly in sheltered terrain features. No avalanches have been observed on these layers to date.
In the north of the region, another melt-freeze crust may be found near the base of the snowpack, which could have a weak layer of sugary faceted grains around it. Snowpack tests and a recent human-triggered avalanche suggest that this layer could be triggered by humans and form large avalanches.
