Observation: Public

Observation Details

Signs of Unstable Snow

Observations

Traveled on a range of aspects below treeline, and NE-SE aspects near treeline. Overcast day with some low clouds in the valleys. Very light winds with recently formed ~1F stiff slabs near ridgelines and sporadically lower on the slopes of an east facing burn area. Soft riming near ridgeline.

Found minimal direct signs of instability, though we were able to get some small isolated wind slabs to fracture.
More importantly, we consistently found the poor structure of weak snow over a crust. In some hand pits a thin layer of surface hoar was apparent a few inches above the December 9th crust as well. In general we found 15-25cm of recent snow over this crust above 5,000ft, with up to 30cm in a few areas from wind drifting.

The higher we went, the weaker and more pronounced the layer of weak snow over the crust was. Above 5,400ft the grains were more angular and slightly larger facets (1-1.5mm).
Snowpack tests results showed sudden failures at this interface. They also hinted that we didn't have enough of a slab yet for this layer to be a problem, but it is the main layer of concern moving forward. Below ~4,500ft the recent snow seemed well bonded. Here the snowpack is shallow, previously soaked through by rain and refrozen, so there are no layers of concern.

-Matt P and Josh H