Possible problematic weak layer around Carson Pass.

We went to Elephant's Hump near Carson Pass today to have a look at a potential weak layer buried in the snowpack that may not support loading from the approaching storm. Similar to what we saw yesterday on Relay Pk (Mount Rose area), there is a potentially problematic weak layer of faceted snow at the interface of the Nov 7 and Nov 13 snowfall events, basically mid height in the currently 1 foot deep snowpack (see photo in Relay Pk observation.). We saw repeatable sudden collapse results in the compression test in two different below treeline snowpits (NNW aspect at 8,475' and NNE aspect at 8,825'). Both of these below treeline locations were open areas with decent wind protection from previous scouring by NE winds. ECT and PST did not show propagation, but this was expected due to the absence of a substantial overlying slab and snow load. We have concern for the possibility of persistent slab avalanches on this weak layer after it snows tonight/tomorrow.

This weak layer seemed fairly widespread on NW-N-NE aspects in the areas that are 1) above about 8,300', and 2) in near treeline to below treeline terrain where NE wind protection exists. Above treeline, this weak layer appears to have been scoured away by strong NE winds following the Nov 7 snowfall. Below 8,300', a warm snowpack appears to have bonded this layer.