The snowpack structure this season is much more complex than we have seen in a long time. Conditions aren’t what we typically see in the Sierra. Since the last major storm of Thursday thru Saturday, wind slabs and storm slabs have settled, but deeply buried weak sugary facet layers remain reactive. There is a narrow band where this concern exists, but it is a big enough concern with the potential for large and destructive human triggered avalanches that we have kept the danger rating CONSIDERABLE until more time has passed to allow the upper snowpack to settle more, and the likelihood of triggering to decrease. With warmer temperatures, these deep weak layers will gradually strengthen, but they will remain a lurking concern for some time. You won’t find this a concern in lower elevation slopes which weren’t covered in snow prior to this recent storm. Upper elevation exposed areas could be less likely as well either due to much deeper snow deposits, or significant bridging from thick hard wind-slabs. The middle elevations which have been covered with enough snow all season to cover up bushes and other potential anchors are the most concerning in terms of the greatest potential for a large deep slab avalanche occurring. Mammoth and June areas seem to be the most concerning where this problem is more widespread, as opposed to further south toward Bishop and north toward VA lakes where snow lines were previously much higher and the band of sheltered snow coverage much more narrow.
Besides avalanche concern, lower elevation slopes which were previously very thin or bare before this last storm have lots of barely covered obstacle.