Precipitation and snow budget over the southwestern United States during the 1994–1995 winter were simulated using an interactively coupled mesoscale atmosphericland surface model. Temporal and spatial distributions of simulated precipitation agreed closely with available observations. It is found that precipitation in California is closely correlated with the moisture influx from the Pacific Ocean. The observed and simulated precipitation indicates that over 70% of the total precipitation in the area during this period was associated with less than 30% of the total winter storms passing this region. Amounts of the simulated season total precipitation generally increased with elevation, with maximum precipitation, mostly in the form of snow, occurring along the ridge of the Sierra Nevada. Simulated surface snow budget indicates that snow plays a major role in seasonal surface hydrology at high elevations where most of surface runoff originates during spring and summer seasons.