Avalanche Forecast
Issued: Dec 16th, 2021 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.
ghelgeson,
Avalanche Canada
Strong Southwest wind is expected Thursday night, but we don't think there is much snow available to be formed into fresh slabs. That being said, there might be some fresh wind slabs on north facing terrain Friday.
Summary
Confidence
Low -
Weather Forecast
The wind shifts direction, but it's still cold.
THURSDAY NIGHT: Overnight low temperature around -25, strong southwest wind, trace of snow possible.
FRIDAY: Broken cloud cover, daytime high temperature around -15, moderate southwest wind, trace of snow possible.
SATURDAY: Scattered cloud cover, daytime high temperature around -20, light variable wind, no snow expected.
SUNDAY: Scattered cloud cover, daytime high temperature around -20, light to moderate north/northeast wind, no snow expected.
Avalanche Summary
No recent avalanche observations have been reported.
Several avalanches to size 1.5 were observed on south facing aspects Monday, the result of last weekend's strong north wind event.
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.Â
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.Â
Snowpack Summary
Northerly winds have gotten into almost all the terrain of the White Pass, even down into the trees at lower elevations which has resulted in quite a bit of wind slab development on south facing features. Big thanks to the party who submitted this MIN on Sunday! Lots of shooting cracks were observed as they were out in the Fraser Chutes Sunday. It is getting pretty hard to find snow that is not wind effected.
The middle snowpack is supportive to travel but snow depth still varies greatly with aspect and elevation.Â
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 or if a cornice fall or surface avalanche impacts a slope. If triggered, this basal layer 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
- Watch for areas of hard wind slab on alpine features.
- Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
- Be aware of the potential for large avalanches due to the presence of a deep persistent slab.
Problems
Wind Slabs
The wind is expected to be strong southwest Thursday night, but there isn't much snow available for transport. That being said, there might be some fresh wind slabs on north facing terrain Friday. Previous to this, winds were light all week. Wind slabs formed last weekend are likely growing quite stubborn as they age in the frigid air.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
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
Valid until: Dec 17th, 2021 4:00PM
