Assessing the sensitivity of Wasatch Mountain winter precipitation to future climate temperature

Since global climate simulations are unable to resolve narrow mountain ranges (such as the Wasatch of northern Utah), lower confidence is generally given to the specifics of the model precipitation estimates in such areas. The objective of this study is to isolate the potential impact of future temperature changes in the intermountain West upon winter precipitation. We assume that general circulation models are able to resolve year-to-year regional variations in mid-tropospheric fields such as temperature and wind, although biases between rawinsonde observations and the present climate simulations are evident locally. A proxy relationship between rawinsonde mid-tropospheric parameters and the fraction of precipitation falling in the Wasatch as snow versus rain is developed in a companion study. This downscaling approach is tested using present climate simulations and then applied to future greenhouse gas emission scenario simulations. The change in percentage of precipitation falling as rain rather than snow per degree Celsius increase in temperature is estimated.