Keep buried weak layers and potential for persistent slab avalanches in your mind. The likelihood of triggering them may be diminishing but if you're unlucky enough to do so, consequences are high. A complex snowpack like this is best managed with conservative terrain choices.
Friday night: Mostly cloudy, light southwest wind, freezing level valley bottom.
Saturday: A mix of sun and cloud, moderate south wind, alpine high -8, freezing level valley bottom.
Sunday: A mix of sun and cloud, strong south wind, alpine high -7, freezing level 900 m.
Monday: Flurries, trace, strong south wind, alpine high -6, freezing level 1200 m.
We have had a few recent reports of natural wind slab avalanches, size 2 out of steep alpine terrain on north to east aspects. Wind slabs likely remain triggerable, especially by humans.
Although the persistent slab problem is trending towards being less reactive, the possibility of triggering it remains, and these avalanches would likely be large.
Field observations in this region are limited. If you get out, please consider submitting your observations to the Mountain Information Network.
20-50 cm of recent fresh snow reportedly sits on a weak layer of surface hoar in many areas. It is suspected that this layer is most prevalent at treeline and below treeline. Recent strong winds have redistributed the storm snow and created wind slabs in lee terrain, especially at higher elevations.
A persistent weak layer is now down about 70-100 cm. The distribution of this layer is variable. In some areas, it's surface hoar and/or a crust. In other areas, this layer may be difficult to find, if it exists at all. This layer has been reported as very prevalent in areas near 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, where the snowpack transitions from thin to thick over a short distance.
Terrain and Travel
- Be especially cautious as you transition into wind affected terrain.
- Keep your guard up at lower elevations. Wind slab formation has been extensive.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
Recent strong winds have formed widespread wind slabs in lee terrain all the way down below treeline in some areas.
Aspects:North, North East, East, South East, West, North West.
There are two persistent weak layers of concern within the snowpack. The shallower one consists of surface hoar and is down around 20-60 cm. At this depth, it remains triggerable by humans.
The second layer is more variable but consists mainly of a crust and/or surface hoar down 70-100 cm. This layer has been found to be most prevalent at and below treeline in areas near Valemount.
Elevations:Treeline, Below Treeline.
Valid until: Jan 9th, 2021 4:00PM