Ocean fronts and eddies force atmospheric rivers and heavy precipitation in western North America

Abstract Atmospheric rivers (ARs) are responsible for over 90% of poleward water vapor transport in the mid-latitudes and can produce extreme precipitation when making landfall. However, weather climate models still have difficulty simulating predicting landfalling ARs associated precipitation, highlighting need to better understand AR dynamics. Here, using high-resolution observations, we demonstrate that mesoscale sea-surface temperature (SST) anomalies along Kuroshio Extension exert a remote influence on related heavy west coast North America. Inclusion SST forcing simulations results approximately 40% increase up 30% mountainous regions this impact occurs two-week time scales. The asymmetrical response atmosphere warm vs. cold SSTs eddy-rich region is proposed as mechanism net moisture flux above planetary boundary layer, prompting genesis via enhancing into extratropical cyclones presence forcing.