Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1.5–2.5
Slabs overlying weak layers buried 2-3 feet deep remain possible to trigger on very steep slopes over 35° in the upper elevations. Signs of instability such as cracking, collapsing, or recent avalanches may not be present before triggering a large, dangerous avalanche. These avalanches are capable of propagating far across or upslope making escape difficult. Multiple tracks on a slope do not indicate stability with this problem type. Large triggers such as cornice falls and groups increase the odds of impacting buried weak layers. Steer clear of very steep, rocky, and wind affected slopes to avoid dealing with this avalanche problem today.
Yesterday, a large avalanche was triggered by a snowmobiler on Mount Leidy. This avalanche likely involved persistent weak layers and is evidence that riders still have the potential to impact these layers.
(2/27/2025)
Steep, rocky, and wind affected terrain above 10,000’ near Togwotee Pass. The boundary between wind scoured and wind loaded features are the most likely places to trigger a persistent slab avalanche.
Photo: Bridger-Teton Avalanche Center