Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 2–2.5
Recent Avalanches: It's been 9 days since the last significant natural avalanche cycle in the Turnagain Pass. While most of this occurred on Seattle Ridge, we also saw multiple human-triggered avalanches on Sunburst and the Tincan trees. New glide avalanches continue to be observed daily in Girdwood, Turnagain Pass, Summit Lake, and Seward.
The multiple weak layers of buried surface hoar in the upper 3' of the snowpack remain the main concern for now. These layers are slowly gaining strength, but it is really hard to say just how reactive they remain. Although they are trending in the right direction, we're still concerned that somebody will trigger a large avalanche on one of these weak layers. Here are a few things to keep in mind as you travel:
- These layers give unreliable feedback, often lacking any warning signs even when conditions are dangerous.
- These layers are slow to heal, and often catch people by surpise days or weeks after they are buried.
- As of now, the most likely place to run into trouble will be at upper elevations where there is no crust on the surface. In other words, exactly where the best surface conditions exist.
You can minimize your exposure to a problem like this by choosing simple terrain with lower slope angles and no consequential features like gullies, cliffs, or trees in the runout zone. We're heading in the right direction with the stability trend, but this is still a problem that should be treated with caution.
Wind Slabs: The slight increase in winds yesterday afternoon have likely built small but reactive wind slabs at the highest elevations in Turnagain Pass. These will be around a foot deep or deeper, and they will still be reactive today. Be on the lookout for this problem in steep terrain just below ridgelines, convex rolls, and in steep gullies. If you notice a transition from softer snow to punchy, stiffer snow on the surface as you travel, you have likely found a wind-loaded slope. There is a chance that even a smaller wind slab triggered at the surface could step down to trigger a bigger avalanche failing deeper in the snowpack, described in Problem 1 above.
(11/29/2025)
This picture is a week old, but we're still worried about the potential to trigger an avalanche on one of several layers of buried surface hoar. The layer marked in this pit was most likely the culprit for the last major avalanche cycle at Turnagain Pass.
Photo: Daniel Krueger
