Turnagain Pass

The last reported natural activity was on Saturday when sunny skies and warm temperatures triggered wet loose avalanches that were pulling out small slabs in some cases. The last known human-triggered avalanches were 9 days ago, with multiple people getting caught and carried in avalanches failing on buried surface hoar.

We are slowly seeing evidence that the layer of buried surface hoar (now 2-3′ deep) that has been the culprit for many natural and human-triggered avalanches is gaining some strength. It has now been 9 days since the last human-triggered avalanche on this layer, and it is becoming harder and harder to find unstable test results or warning signs like shooting cracks or collapsing. Although it is still possible to trigger an avalanche on this layer, it is feeling less dangerous now than it was a week ago.

With a little more confidence in this weak layer, we are slowly starting to move back into steeper terrain. This needs to be done carefully, which means taking the time to assess the snowpack for the zone you are traveling in and choosing terrain wisely. At this point we are just dipping our toes in the water, not diving into the deep end. There is still some uncertainty with just how reactive the layer is, and you can minimize the consequences of triggering an avalanche by choosing smaller terrain with clean runout zones free of terrain traps like gullies, cliffs, trees, or rocks. For this type of problem, it is worth taking the time to dig a quick pit to test the layer as one final check before jumping on steeper slopes. If you get an unstable result, it’s a sign to stick to low-angle terrain. As always, only expose one person at a time, and keep an eye on your partners from safe spots out of avalanche runout zones. The lingering potential for triggering a massive avalanche on the Thanksgiving crust/facet layer deeper in the snowpack (see problem 2) should be one more reason to stay on smaller terrain for now. Remember, you can avoid this problem entirely by sticking to slopes less than 30 degrees.

Wind Slabs: It is likely some wind slabs formed with moderate easterly winds over the past 24 hours. These will remain reactive on isolated upper elevation slopes today. Be skeptical of steep slopes just below ridgelines, in steep gullies, or on convex rolls. Avoid steep terrain with stiff snow on the surface sitting on top of softer snow. There is a chance that a relatively small wind slab avalanche could step down to the buried surface hoar layer, triggering a larger avalanche.

CNFAIC intern Megan Guinn checking out our surface hoar layer on Max’s before we got into the steeper terrain near the top. 01.29.2023

Even though it is becoming less likely, we aren’t quite ready to ignore the weak layers of facets surrounding the Thanksgiving crust. This is now buried around 4-8′ deep on average. It has been over three weeks since the last human-triggered avalanche on this layer, and two weeks since a natural avalanche stepped down to the layer. This layer is most problematic in areas with a thinner snowpack at elevations above 2500′. Although it is unlikely a person will trigger an avalanche on a layer that deep, the consequences of getting caught in something that big would be severe. This is just one more reason to be careful in the way you approach moving into steeper terrain, starting with smaller features and letting the ‘big game’ terrain wait for now.

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