Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1–2
The incoming storm will increase the chance of triggering an avalanche on a layer of surface hoar buried around a foot deep or deeper. The storm may delivers around 4” of new snow accompanied with strong southeast winds. Wind loaded slopes where wind slabs are forming above this weak layer will be the easiest places to trigger a persistent slab avalanche.
On Saturday a skier triggered collapses/whumps on Colorado Mtn. This is a bullseye clue telling us the snowpack is unstable. However, there may not be clues present. In Turnagain Pass snow tests have been unreliable meaning they give stable results on the same slopes we are seeing avalanches. They have also been remotely triggered meaning that people have triggered avalanches above or adjacent to them from low angle slopes. This may become a problem in Summit Lake especially on slopes where wind slabs are forming.
Blowing snow and traveling on stiffer snow are clues you are traveling on a wind slab. Whumpfing sounds and shooting cracks underneath indicate a wind slab and/or weak layer is being triggered by your weight. We recommend choosing more conservative objectices and looking out for areas below ridgelines, in big bowls, convex rollovers, and in loaded gullies where it will be easier to trigger a persistent slab avalanche.
Cornices will be growing all day which could increase the chance of them falling and triggering an avalanche above you.
Glide Avalanches: Glide cracks will likely be hard to see today. They are still releasing as glide avalanches so try to avoid traveling under these. If you do encounter one, spend as little time underneath them as possible.
(3/17/2025)
The approaching storm is expected to bring strong southeast winds a few inches of snow. This will increase the chance of triggering a avalanche on a layer of surface hoar buried around 1' deep.
Photo: Daniel Krueger