Professional Observation

Observation Details

Signs of Unstable Snow

Snow Stability

Bottom Line

Payette Powder Guides Andy Keck and Nate Giles, along with some excellent help from a Level 2 class, found the surface hoar layer buried on 12/20 to be the primary weak layer of concern on all aspects in the mid and upper elevation bands they observed. A combination of new snow and swirling winds over the past 48 hours has left this layer buried approximately 45cm down. The PPG staff found this layer to be widespread and touchy. They were able to intentionally trigger a D1.5 avalanche that failed on this layer and propagated across a confining terrain feature. What was most surprising was the apparent stout-ness of this surface hoar. The winds associated with this most recent storm were not able to knock down the surface hoar. We found this layer to have grains averaging 7mm. Applying lemons/yellow flags to this layer we were able to count 5 out of 6. The slab on top of this SH layer is still very soft (F to F+) in protected areas, however in areas of wind deposition it is more dense and as such, more likely to propagate. We agreed that this event in unusual for this area and will most likely take some special precautions in the upcoming weeks to confidently manage it.