Wind Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Unlikely
- Size
- 1–1.5
On Thursday at Ball Butte, I was pleasantly surprised to encounter more new snow than the Mt Bachelor snow stake led on to. In the afternoon, open meadows at around 7000' elevation were showing ~6 cm of recent storm snow overlying a pre-storm surface crust. As I climbed higher and poked around, I observed lee slopes immediately below ridges consistently having 15–20 cm of wind loaded snow. These snow depths varied with elevation and terrain features; on one E facing slope at 8050', just below a ridge there was 30cm of recent wind blown snow (worth noting that this was in a heavily loaded area where the height of snow was over 3 meters). All that being said, these wind drifts were generally isolated to the upper section of the slope just below ridgelines, so within a few turns down-slope, conditions became more of a "dust on crust" situation. Also worth noting that in these loaded pockets, I did not observe any red flags such as shooting cracks, and it appeared that the new snow likely fell relatively warm and wet, which will often create a strong bond to an underlying crust.
On lee slopes at our uppermost above-treeline elevations, I would expect these isolated wind drifts to be more in the category of "stubborn" rather than "unreactive". These upper elevations will also likely have larger pockets of deep wind drifts. All of this still puts the likelihood of triggering an avalanche at "unlikely", but that's not to say impossible. If you were to trigger a slide anywhere on Friday, it would be on steep slopes in these locations. Pay attention to warning signs such as shooting cracks if you venture into this terrain, and monitor snow depths and snow structure as you travel. Strong over weak snow represents the presence of a slab, and poor snow structure. Heed these warning signs should you encounter them.