Avalanche Forecast
Issued: Dec 18th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs and Wind Slabs.
ghelgeson,
Avalanche Canada
The White Pass is heavily wind effected and conditions don't look that inviting. The 5 cm of snow that fell Friday is likely being formed into small wind slabs that sit on a mix of sastrugi and old wind slab. Remain mindful that a deep persistent slab is present.
Summary
Confidence
Weather Forecast
SATURDAY NIGHT: Light northeast wind, overnight low temperature around -22 C, no snow expected.
SUNDAY: A few clouds, daytime high temperature around -18, moderate north wind, no snow expected.
MONDAY: A few clouds, daytime high temperature around -16, moderate to strong northwest wind, no snow expected during the day, a few cm possible Monday night.
TUESDAY: Broken cloud cover, daytime high temperature around -12, strong north wind, a few cm of snow possible.
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 white pass is looking heavily wind effected as evidenced in this MIN. Recently winds have been out of the southwest and northwest, there may be small wind slabs in areas where there remains snow available for transport.
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.
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
There's been a few cm of snow this week, small wind slabs may have formed in areas where there remains snow available for transport.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Dec 19th, 2021 4:00PM
