The American West is seeing less snow and more rain

The American West is warming, especially in winter and spring — which means that more rain is falling, and less snow. In fact, the fraction of annual precipitation falling as rain rather than snow increased at 74% of weather stations in the mountains of the western US between 1949 and 2004.[[Knowles, N., M.D. Dettinger and D.R. Cayan, 2006: “Trends in snowfall versus rainfall for the western United States,” (PDF) 1949-2004. J. Climate, 19, 4545-4559. PDF]] More recent studies show similar findings.[[Hamlet, A. F., P. W. Mote, M. P. Clark, D. P. Lettenmaier, J. “Effects of Temperature and Precipitation Variability on Snowpack Trends in the Western United States” (Abstract) Clim. 18, 4545 (2005).]]

This trend means decreasing snowpack and earlier snowmelt, which translates to a wide range of consequences, from problems with agricultural water supply to increased wildfires to dangers for trout habitat, to name a few.