Snow accumulation patterns in the Sierra Nevada

This paper examines the spatial characteristics of snow accumulations in the Sierra Nevada. In particular, it addresses the question of whether snow courses located within individual basins, but at differing elevations, are more consistent in having above or below normal accumulations than are locations of similar topography but greater spatial separation. Nearly thirty years of data for Feb. 1 and April 1 were obtained for 28 snow courses. The data were standardized and subjected to principal complonents analysis to obtain preliminary results regarding the homogeneity of the snow accumulation across the Sierra. Most stations were highly correlated with each other and loaded strongly on the first component. However, several sites at lower elevations exhibited less uniformity with the other snow courses. This results from the influence of warm weather precipitation being in the form of rain instead of snow at the lower elevations. More detailed examination of accumulation patterns will also be presented.