River basin variations in Sierra Nevada snowpack accumulation trends

Mountainous areas, particularly in the western United States, provide a large fraction of the fresh water supply. This reserve, which supplies most of California's growing water needs, is vulnerable to changes in climate. Regional precipitation patterns, especially snow, which is a sensitive indicator of change, are predicted to vary according to future climate models. This study uses a statistical model which links snow water equivalent (SWE) measurements over a 6O-year time series to analyze the snow accumulation trends in the Sierra Nevada.We utilized snow course measurements with data difficulties including inconsistent monthly sampling, added and removed stations and possibly a few moved or otherwise altered snow courses. To determine the effects of a monthly and irregular sampling schedule we analyzed daily snow sensor data spanning 25 years. Furthermore, we employed a statistical test to check for possibly discontinuous snow course stations.We found that the overall maximum amount of seasonal SWE is not changing. However, below 2700 meters, snowmelt timing has recently been occurring earlier, whereas elevations above 2900 meters are melting later. The eastern draining river basins consist of steeper, drier slopes that have mostly increasing SWE trends. The Owens River basin, in the southeastern tip of the range, has gained the most SWE while the neighboring, westside Kern has received less snow.