Avalanche Forecast
Issued: Dec 14th, 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
Wind slabs are likely getting more difficult to trigger, but we'd still suggest avoiding steep south facing terrain where wind slabs are probably thick and hard. If you are getting out, please submit to the Mountain Information Network and let us know what you're seeing.
Summary
Confidence
Weather Forecast
Still cold for the foreseeable future.
TUESDAY NIGHT: Overnight low temperature around -28, light variable wind, no snow expected.
WEDNESDAY: Scattered cloud cover, daytime high temperature around -24, wind begins to pick up midday mainly out of the northwest, could be strong to extreme Wednesday night at upper elevations, no significant snowfall expected during the day or night.
THURSDAY: Clear skies, daytime high temperature around -28, strong northwest wind at upper elevations, no snow expected during the day, a few cm possible Thursday night.
FRIDAY: Scattered cloud cover, daytime high temperature around -18, moderate southwest wind at upper elevations, a few cm of snow possible.
Avalanche Summary
Several avalanches to size 1.5 were observed on south facing aspects Monday, the result of last weekend's strong north wind event.
Explosive control earlier in the month produced many large avalanches that failed on the weak sugary crystals at the bottom of the snowpack. These avalanches ran full path.
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
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.
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
Wind slabs on south facing aspects are the most likely to remain sensitive to human triggering Wednesday, but they are likely getting harder to trigger as time and frigid temperatures sap them of their energy.
Aspects: East, South East, South, South West.
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. Decreasing temperatures will initially make it harder to trigger this problem but if the cold persists, the failure layer will become weaker and we may eventually see sensitivity creeping up again in the coming days
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 15th, 2021 4:00PM
