Pro Field Report

Observation Details

Signs of Unstable Snow

The new snowfall over the past 3 days (~ 30 cm) has remained touchy on the O/N interface, likely running on NSF or SH and sitting on a large layer of well-developed facets (HS 77 cm). I would not be surprised if wind loaded terrain or steeper features stepped down to deeper layers in the upper elevations. I encountered large collapses skinning along Banner, and road cuts/slopes along Lowman road had avalanched naturally, likely yesterday post-storm. Half looked plow-triggered, half not, dependent on steepness of terrain. The soft slab problem will likely heal, though may remain a larger issue in wind-loaded upper elevation terrain or if any stiffening of the new slab occurs (wind, solar). ECTN7 @ 50cm up, though lack of propagation was not surprising given the soft nature of the slab (PST 12/100 SF). I found no visible SH in my Banner pit. Structure in the lower pack in this area is not faring worse, however the upper half (notably large facet layer ~ 50-30 cm) is not looking good.

Snow Stability

Bottom Line

The new snow still seems sensitive to trigger on the old/new interface, and will pose a hazard in any wind-loaded terrain, steeper terrain, or in lower elevation terrain-trap features. Likely culprits are SH or NSF (on slight crust dependent on aspect), but overall a larger layer of faceted old snow. I noted nearly 20 avalanches between Lowman and Stanley, with the new snow communicating well with itself and capable of propagating long distances (note long, well-connected crown lines wrapped around terrain features).