Avalanche Forecast

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.

• Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
• If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
• Use small low consequence slopes to test the bond of the new snow.
• Be alert to conditions that change with elevation.
• Be cautious of buried obstacles especially below treeline.