The Influence of Atmospheric Rivers on the Seasonal Snowpack in the Columbia River Basin

The Columbia River in the Pacific Northwestern United States has a strong influence on the regional ecology and economy through its contribution to water resources. A primary hydrologic contributor to the Columbia River Basin is the melting of a seasonal snowpack. The timing and amount of melt can be consequential, supporting the motivation to understand possible mechanisms driving the melting of the snowpack in this basin. One potential driver influencing the variability of the seasonal snowpack is the influence of enhanced mid-tropospheric moisture transport known as “atmospheric rivers” (ARs).

Using data from existing AR and SNOw TELemetry data sets, we employed a suite of exploratory analyses to assess the relationship between AR activity and snow water equivalent (SWE) in this river basin by considering both monthly and seasonal accumulations and depletions. A simple climatology of AR activity in this region indicates a lack in seasonality. While total seasonal SWE at stations located in the western portion of the basin was slightly higher in years of high AR activity, monthly analyses show that the variability of SWE gain and depletion is also greater during years of high AR activity. Variations of SWE show some dependence on AR activity, and this dependence is likely further influenced by geographic location (e.g., latitude, longitude, and elevation) as well. However, the external atmospheric drivers (i.e., teleconnection patterns) associated with high AR activity may be of greater importance than AR activity within the basin itself. These results may indicate to water resource management teams that during years with a strong presence of ARs, consideration for location should be used when trying to prepare for shortages and/or surpluses in yearly water supplies.