Intense precipitation and flooding in the western US are often associated with atmospheric rivers that transport significant amounts of moisture from the tropics to the west coast. As part of the North American Regional Climate Change Assessment Program (NARCCAP), simulations have been performed using the Weather Research and Forecasting (WRF) model for North America at 50 km horizontal resolution. Three sets of simulations, one driven by large scale conditions from the NCEP/DOE global reanalysis, and two driven by the Community Climate System Model (CCSM) for 1970 - 2000 and 2040-2070 are being analyzed to elucidate the ability of the downscaled simulations in capturing the intense precipitation associated with atmospheric rivers that influence the west coast and potential changes in the future climate. Such analysis will be complemented by analysis of the large scale environments simulated by the CCSM that provides boundary conditions for downscaling of regional climate change.