Primary Atmospheric Drivers of Pluvial Years in the United States Great Plains

Precipitation variability has been increasing in recent decades across the Great Plains (GP) of the United States (US). While drought and its associated drivers have been studied in the GP region, periods of excessive precipitation (pluvial) at seasonal to interannual scales have received less attention. This study narrows this knowledge gap with the overall goal of understanding GP precipitation variability during pluvial periods. Through composites of relevant atmospheric variables from the ERA 20^th Century (ERA-20C) reanalysis, we highlight key differences between Southern Great Plains (SGP) and Northern Great Plains (NGP) pluvial periods along with the precursor patterns to these pluvial events. The SGP pattern shows an area of negative height anomalies over the southwestern United States along with increased wave activity and a shift in the typical North Pacific waveguide. The NGP pattern is similar, with an area of negative height anomalies over the northwestern US, however no increased wave activity or shift in the North Pacific waveguide is seen. Lastly, analysis of these patterns with sea surface temperature anomalies over the Pacific details a possible connection between the occurrence of these patterns and the Pacific Ocean variability. Together, these results present a possible pathway to predicting the occurrence of pluvial years over the GP. With a better understanding of the causes of precipitation variability over the GP, the threat of water scarcity can be better managed for the public and agricultural sectors.