Evaluating this persistent slab issue has led to many conversations amongst the forecaster staff. The very shallow nature of the snowpack has in many ways been beneficial from an avalanche standpoint. Sparse coverage broken by exposed areas of bare ground has limited the areas with enough contiguous snow cover to produce a sizable avalanche. In addition, the coverage is so thin in many areas that the current “slab” is broken by small trees, rocks, and bushes that are effectively working as anchors to the snowpack. However, this fine balance is likely to change with the addition of a significant new load. Recent observations have shown the very poor structure remains and in fact may be degrading as the weak sugary snow persists and the overriding slab has settled and gained strength. Stability tests in the Mammoth area and in Virginia lakes have confirmed this trend, and recent avalanche activity reported in the Virginia lakes area highlights the potential for the scales to tip with the addition of a new load.
Make no mistake we do not have a typical sierra snowpack at the moment. Instead, we have a snowpack much more similer to something you would expect to find in Colorado or Utah. As we continue to do our snow dance and hope for some significant snowfall in the near future, it will be important for us all to remain vigilant. A new load of snow may just tip the scales and kick off a cycle of instability.