Persistent Weak Layers around Polaris Point

Limited snow coverage existed below 7400 ft. in this area. Numerous logs, stumps, and rocks remained exposed. More creeks with more water than usual also existed on the approach, and creek crossings proved difficult. Above 7800 ft. snow coverage improved. On shaded aspects, the surface snow remained cold, soft, and unconsolidated except in areas where snow falling off of trees had left a more frozen firm snow surface. On sun exposed slopes the snow surface became wet and sticky by mid-day. 

Where continuous snow cover existed on the northerly aspects the recent snow is resting on top of a loose weak layer of near crust facets (the 12/15 NCF's) above the 12/15 rain crust. In some areas (see snowpit and video) on open northerly facing slopes sheltered from the wind, a layer of buried surface hoar existed in the snowpack between the 12/15 NCF's and the recent snow. In these areas, snowpit tests yielded unstable results. In other areas snowpit data and tests did not find this buried surface hoar layer and the 12/15 NCF's were less well developed. In these areas, no signs of instability existed. Snowpit tests performed on a NE facing slope at 8000 ft. @ 39.12918, -120.20596 resulted in ECTN's and either PST SF's or PST ENDs at more than half the column length. All of these results indicate that fractures are unlikely to travel along the 12/15 NCF's in that area. Overall a variable snowpack with variable weak layers existed in this area. 

Photos 1 and 2: The buried surface hoar layer above the 12/15 NCF's.

Video: ECTP on the persistent weak layers.