Two storms have blanketed the Sierra Nevada in snow, pushing the snowpack to 106 percent above average, with the start of winter more than a week away. At the same time last year, the Sierra snowpack was 47 percent of average. A series of systems starting around Thanksgiving dropped several feet of fresh powder in some mountain areas. In the southern Sierra, Mammoth Mountain has recorded nearly 6 feet since October 1. The ski resort claims to have the deepest snowpack in the country right now.