Deep Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1.5–3
There is a chance a human could trigger a large avalanche on a buried weak layer of snow 2 to 5’ deep above 2,500’. Summit Lake has weak snow buried over a large slab which are the ingredients for a deep slab avalanche. This problem is tricky because it may be less likely but the consequences are high.
Even though this problem will decrease over time, triggering a wind slab avalanche today could trigger one of these larger avalanches. Areas where the snowpack is thin is also an easier place to trigger a deep slab avalanche like near exposed rocks and close to ridges. A “whumpfing” sound or collapse indicates you could trigger an avalanche if the slope was steep enough. These clues may not exist until you trigger an avalanche on a slope. Because this problem is so tricky to assess, the safest option is to enjoy fresh snow on lower angle slopes.
Recent Avalanches: The storm produced some large avalanches in the Girdwood valley and Summit Lake. Poor visibility has made it difficult to see if these avalanches were in the storm snow or from weak layers deeper in the snowpack.
Dry Loose Avalanches: There is a good chance of triggering a dry loose avalanche on steep slopes. This problem could have higher consequences if carried into terrain traps and gullies where snow can pile up.
Cornice Falls: Cornices have likely grown in size during the storm. Try to avoid spending time under them as they can be a large trigger to slopes above you. If you find yourself on a ridge, give these some room as they can break under you.
