Turnagain Pass

• Lynx Creek – Looks like a new glide avalanche released on the lower portion of Lynx creek sometime in the past 48 hours. It is hard to believe and hard to see because of the cloud sandwich in this photo, but we received multiple reports from reliable sources.

Photo taken from Cornbiscuit on 12.17.21

Today will bring another day of calm weather, with cloud cover being the limiting factor but the visibility should improve throughout the day. It has been over a week since our last significant snowfall and other than some wind loading events the forecast area has been largely quiet since then in terms of avalanche activity. While the faceted weak layers buried 3-5′ deep have been gaining some strength during that time it typically takes weeks or longer for this type of weak layer to stop being possible to trigger. The lack of recent avalanche activity could start to lure us into a false sense of security about the stability of our faceted weak layer, but it is important to remember that deep persistent slabs are defined by their lack of feedback before producing large and destructive avalanches.

Here are some of the common characteristics of a deep persistent slabs:

• Difficult to trigger – stubborn
• Capable of producing very large avalanches that could propagate across terrain features
• No signs of instability before a slope releases
• Can be triggered after many people have been on a slope
• Can be triggered remotely (from the side, top or below)
• The slab itself is more than 3′ deep and is composed of hard snow

These characteristics are what make deep persistent slabs so hard to evaluate and manage. The potential to trigger one of these avalanches has probably decreased over the last week but we are still seeing poor structure in our snowpack and signs of propagation in stability tests (videos from Magnum and Cornbiscuit). Triggering a deep slab is easier in areas with a thin snowpack, which is the case in the southern portion of the forecast area and even more so as you get closer to Summit Lake. Most of the avalanche activity we have seen on this layer is in the 1,500 to 3,000′ elevation band.

To minimize your exposure to this avalanche problem we recommend steering clear of large slopes with slope angles greater than 30° and being aware of steeper slopes above you. If you decide to step out into avalanche terrain it is wise to follow safe travel protocols, like having only one person at a time in avalanche terrain and always spotting your partners.

Our basic snowpack structure between 1500 – 3000′. Photo from Cornbiscuit on 12.15.21