Avalanche Forecast
Issued: Nov 26th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
ahanna,
Avalanche Canada
Watch for fresh, reactive wind slabs at upper elevations and be aware of the potential for larger avalanches due to a crust that was buried in early November.
Summary
Confidence
Weather Forecast
Thursday night: Up to 5 cm new snow, strong southwest wind, freezing level 1200-1500 m.
Friday: 5-10 cm new snow, strong southwest wind, freezing level 1600 m.
Saturday: 5-15 cm new snow overnight then clearing, moderate west wind, freezing level 500 m.
Sunday: Sun and cloud, light southerly wind, freezing level 900 m.
Avalanche Summary
In the south, size 1-1.5 loose dry avalanches were observed in recent storm snow running on a melt-freeze crust in steep south-facing terrain on Wednesday.
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.
Snowpack Summary
New snow is falling amid strong to extreme southwesterly wind, likely producing wind slabs in lee terrain features at higher elevations.
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.
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 avalanche activity suggest that this layer could be triggered by humans and produce large avalanches.
Terrain and Travel
- 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.
- Be cautious of buried obstacles especially below treeline.
- Uncertainty is best managed through conservative terrain choices at this time.
Problems
Wind Slabs
New snow is falling amid strong to extreme southwesterly wind, likely producing wind slabs in lee terrain features at higher elevations.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
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.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Nov 27th, 2020 4:00PM
