Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1.5–2
It’s been several days since any significant new snow and the last piece of “bullseye” information (audible whumpfs). The likelihood of triggering a persistent slab is decreasing, but the probability doesn’t matter if it happens to you.
It’s nearly impossible to say which slopes are safe and which ones are not. The only way to completely manage this problem is by avoiding steep open slopes on shaded aspects.
If you’re more willing to roll the dice, there are a few things to keep in mind. Avalanches will be more likely with at least a foot or more of recent snow and where settlement or wind stiffened the slab. This is more common in the western portions of the zone. You may be more likely to find the wrong spot in complex terrain full of rollovers and greater snowpack variability.
(2/3/2025)
Example: A skier triggered persistent slab avalanche near White Pass. This slide released over a 100ft wide and 2-3ft deep. WNW, 5600ft SS-ASu-D2-R2-O
Photo: Dallas Glass