Regional climate models derive benefits over global climate models from a more accurate representation of regional climate forcings, achieved through higher resolution orography, land-water contrasts and land surface characteristics. Regional forcings can produce statistically significant climate signals, particularly for processes forced directly by topography including orographic precipitation and monsoon circulations. Such high resolution climate scenarios are important for resource management and impact assessment.

The Weather Research and Forecasting (WRF) model was designed specifically for high resolution applications, and provides an ideal tool for assessing the value of high resolution (1 - 10km grid-spacing) regional climate modeling. Simulations of the climate of western North America are performed using different model grid spacings. Model evaluation focuses on the statistics of cold-season precipitation, temperature and snowpack over the Pacific Northwest and warm-season temperature and convective precipitation over the Southwest associated with the North American Monsoon. The impact of physics parameterization sensitivity to model grid-spacing may overwhelm any benefits of high resolution simulation and is explored through sensitivity studies.