Avalanche Forecast
Issued: Dec 17th, 2021 1:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs and Wind Slabs.
JSmith,
Avalanche Canada
A weak layer near the bottom of the snowpack remains a concern and may be possible to trigger in isolated locations.
Avoid likely trigger spots such as steep, rocky slopes, with a shallow or thin to thick snowpack.
Summary
Confidence
Weather Forecast
FRIDAY NIGHT: Overnight low temperature around -21, light northwest wind, partly cloudy skies.
SATURDAY: Mix of sun and cloud, daytime high temperature around -18, light northwest wind, no snow expected.
SUNDAY: Mix of sun and cloud, daytime high temperature around -17, moderate north wind, no snow expected.
MONDAY: Sunny, daytime high temperature around -17, strong northwest wind, no snow expected.
Avalanche Summary
No recent avalanche observations have been reported.
On December 1, a size 2.5 avalanche was remotely triggered by a recreational group on Log Cabin. This avalanche likely failed on the weak, sugary snow at the bottom of the snowpack.
Triggering the deep layer (see the December 1 avalanche described above) is most likely to occur in shallow areas or where the snowpack variable in depth with a mix of shallow and deep zones.
Snowpack Summary
The winds have shifted back to the southwest early Friday morning and may form small wind slabs in areas where there remains snow available for transport.
Older wind slabs formed by recent northerly winds may linger in open terrain, but are becoming less likely to trigger with sustained cold temperatures.
The middle snowpack is supportive to travel but snow depth still varies greatly with aspect and elevation.
A layer of weak, sugary snow at the base of the snowpack has been observed in most areas. This layer was reactive earlier in December, and it might still be possible to trigger this deeply buried layer in shallow snowpack areas. A cornice fall or surface avalanche impacting a slope could also trigger it. If triggered, this weak layer at the bottom of the snowpack could produce large avalanches.
This sugary layer will likely become weaker in the coming days with cold temperatures potentially making it increasingly sensitive to triggering.
Terrain and Travel
- Be aware of the potential for large avalanches due to the presence of a deep persistent slab.
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
- This avalanche problem is difficult to trigger but if so, consequences are serious.
- Watch for areas of hard wind slab on alpine features.
Problems
Deep Persistent Slabs
This layer is becoming more deeply buried and somewhat harder to trigger. But it would likely result in a large avalanche if you tickle it from the wrong spot. Most likely trigger points are areas where the snowpack is shallow or variable so avoid fat to thin transitions and stick to places where the snowpack is deep. Remote triggering is possible and a cornice fall or surface avalanche could set off a deeper slide so be aware of your overhead exposure.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
The winds have shifted back to the southwest early Friday morning and may form small wind slabs in areas where there remains snow available for transport.
Older wind slabs formed by recent northerly winds may linger in open terrain, but are becoming less likely to trigger with sustained cold temperatures.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Dec 18th, 2021 1:00PM
