Contribution of Atmospheric Rivers to Seasonal Precipitation in the US Intermountain West

Atmospheric rivers (ARs) are known to bring enhanced precipitation to the west coast of the United States, but their impact on and contribution to precipitation farther inland is less well understood. This study aims to quantify the contribution of AR moisture to the seasonal precipitation in the US Intermountain West. The 2016-2017 winter season saw frequent AR activity in the eastern Pacific Ocean, providing a good opportunity to study the effect of ARs on inland locations in the western U.S. In this study, the 2016-2017 winter season (November 1 – March 31) is modeled using the Weather, Research, and Forecasting model (WRF). The seasonal contribution of ARs to moisture flux and precipitation across the western United States is calculated using output from WRF. Monthly Hovmöller diagrams are used to determine the AR frequency, trajectory, and temporal evolution. And monthly precipitation across the western U.S, as well as the reduction in precipitation, is calculated.