Weather
This cool image, from UCB, shows that with some minor exceptions the bulk of the central Sierra’s snowpack is made up of three major storm periods.
The snowpack has little stored cold content against continued clear weather, meaning that its relatively small mass wouldn’t take much of a temperature rise to begin melting.
This other image, courtesy of the Department of Water Services, shows that the current snowpack for the same area is 30% of average, and the state of California as a whole has a snowpack 24% of average.
