Montana has seen less snow over the past fifty years

The Montana State Climate Office has documented an overall trend of less snowfall in Montana since 1950.[[Running, Steven W. “Annual Mean Temperature,°F 1951-2004.” See Slide 5]] Beyond that, what snow does accumulate during the winter is melting earlier.[[Mote, P.W., A.F. Hamlet, M.P. Clark and D.P. Lettenmaier: “Declining mountain snowpack in western North America,” (PDF) Bull. Amer. Met. Soc., 2005. 39-49.]] These phenomena are consistent with the fact that the west has been warming generally over recent decades, in a pattern that is what scientists expect from human-caused climate change.[[Barnett, T. P., D. W. Pierce, H. G. Hidalgo, C. Bonfils, B. D. Santer,T. Das, G. Bala, A. W. Wood, T. Nozawa, A. A. Mirin, D. R. Cayan, M. D. Dettinger 2008 “Human-Induced Changes in the Hydrology of the Western United States” (Abstract) Science, 329, pp. 1080-1083]]. This warming is projected to increase.

The combined effect of less snowfall and earlier snowmelt has a number of consequences, as in other Western states, including a reduction in late-summer stream flow,[[Stewart, I.T., D.R. Cayan and M.D. Dettinger, 2005:  “Changes toward earlier streamflow timing across western North America,” (PDF) J. Clim., 1136-1155.]] an increase in insect epidemics harmful to forests and an increase in the frequency and severity of wildfires.[[Littell, Jeremy, Donald McKenzie, David L. Peterson, and Anthony L. Westerling. “Climate and wildfire area burned in western U.S. ecoprovinces, 1916–2003” (Abstract) Ecological Applications, 19(4), 2009, pp. 1003–102]] All of these trends are likely to worsen with rising temperatures.