Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Very Likely
- Size
- 1.5–2.5
Avalanches in wind-loaded terrain will be very dangerous and will run naturally. They could break widely across terrain and be very large, even unsurvivable. If you venture into the mountains, be sure of your ability to avoid avalanche terrain, including any overhead, wind-loaded slopes and avalanche paths. Put a wide buffer of terrain between yourself and any wind-loaded slope steeper than 30 degrees. You could trigger avalanches from far away, and they could come down from above.
The most dangerous areas will be above 5,000ft where the wind is depositing snow and forming stiff slabs. Weak faceted snow and surface hoar are resting on a crust, about 1.5-2 feet below the surface. Strong westerly and swirling winds will continue to stress these weak layers as slabs form on lee aspects, even well-below ridgelines. At low elevations, these avalanches may act more like your average storm or wind slab, but you may be able to trigger them longer than normal.
(2/26/2026)
A couple of large, natural avalanches on a leeward slope. Note blowing snow and crowns well below the ridgeline. This likely ran on a weak layer above the 2/7 crust, ~2 feet below the surface. Cutthroat Lake. ESE, 7,000ft
Photo: NCH