Deep Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 2–3.5
Sometime around January 16, an approximately 1.5m thick (possibly thicker) hard slab avalanche occurred in the Silverton Avalanche Path on a northeasterly slope of Fremont. See photo, and get more information here. Additionally, a second avalanche from a similar time period was reported in Jay's Slide on the north northwest side of Fremont. Both of these avalanche likely failed in depth hoar near the ground, similar to the HS-N-R3-D3-O avalanche on Fremont, during the New Year’s storm cycle. So far this season, four known persistent slab avalanches have occurred on northeasterly slopes, with starting zones between ~11,400' and ~11,800'. These avalanches have been large and are a major concern for backcountry travelers. Although these are low probability events the consequences are high, with avalanches likely breaking wider, deeper, are running further than you may expect destroying trees that are 30-40 years old.
North, northeast, and northwest slopes near and above treeline should be considered highly suspect and avoided or travelled on with the utmost care and consideration. You are most likely to trigger these avalanches in areas with a shallower snowpack (< 1 meter) where the weight of a traveler can initiate propagation on the weak layer.
(1/18/2023) Estimated at HS-N-R2-D2-U. Likely failed at depth hoar near the ground, and likely occured on MLK day, January 16, 2023. Photo: Troy Marino
