Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Unlikely
- Size
- 1–3
On Saturday, I found propagation on a facet layer that is buried 22”-31” deep, depending on elevation. Our team has been tracking this layer throughout the season, and these snow grains have been gaining strength. However, snowpack tests reveal this layer still has the potential to cause avalanches.
In addition, forecasters have been finding surface hoar down 18” that was buried on 2/14. This layer has also shown test results that can be consistent with avalanches. Although we have not seen any recent avalanches on these layers, if you were to trigger a persistent slab, it will be very destructive.
Sometimes we do not get many clues of instability (such as cracking or whumpfing) from persistent slabs. However, persistent slabs can be unpredictable and catch riders off guard. It seems unlikley to trigger these weak layers, but due to the weak snow grains and the large slab sitting on top, I plan to give these layers more time to heal before traveling in consequential avalanche terrain in the Paulina area.
(2/28/2026)
Extended column test: ECTP#26 down 22". NW aspect, 7,020ft.
Photo: Elliott Reed