Avalanche Forecast
Issued: Dec 27th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Wind Slabs.
JSmith,
Avalanche Canada
A buried weak layer down 40-70 cm. continues to be a concern and has the potential to create large avalanches. This problem can be avoided through conservative terrain choices.
Summary
Confidence
Low - Uncertainty is due to the limited number of field observations. Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.
Weather Forecast
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SUNDAY NIGHT: Cloudy / Light, west ridgetop wind / alpine low temperature -13 / Freezing level valley bottom.
MONDAY: Mostly cloudy with sunny periods / Light, west ridgetop wind / alpine high temperature -9 / Freezing level valley bottom.
TUESDAY: Mix of sun and cloud / Light, northwest ridgetop wind / alpine high temperature -11 / Freezing level valley bottom.
WEDNESDAY: Cloudy with isolated flurries; 0-3 cm. / Moderate, west ridgetop wind / alpine high temperature -9 / Freezing level valley bottom.
Avalanche Summary
On Monday there was a report of a human triggered avalanche that was suspected to have run on buried surface hoar. The MIN report can be view here.
Data in this region is very sparse. Please submit your observations to the Mountain Information Network.Â
Snowpack Summary
10-15 cm of new snow with light winds over the last couple days.
Winds blowing from a variety of directions last week formed wind slabs in lee features at treeline and above.
An active weak layer is now down 40 to 70 cm. The distribution of this layer is variable. In some areas it's surface hoar and/or a crust; in others this layer may be difficult to find if it exists at all. Recent human triggered avalanches have been reported on this layer and have been most numerous in the areas between Blue River and Valemount.
There is a prominent crust near the base of the snowpack. This crust likely has weak facets above and/or below it. There have been no recent avalanches reported on this layer, but would be most likely to trigger in steep, shallow, rocky terrain, with a thin to thick snowpack.
Terrain and Travel
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
- Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- Be careful as you transition into wind affected terrain.
Problems
Persistent Slabs
A slab rests on a persistent weak layer which has the capacity to propagate avalanches across terrain features. Although the likelihood of triggering a persistent slab avalanche is reducing, the potential for triggering a high consequence avalanche should still be top of mind in your decision making process.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Lingering wind slabs may remain reactive to human triggers on a variety of aspects.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 28th, 2020 4:00PM
