Warm-Season Atmospheric River Clusters and Associated Precipitation Patterns in the Northeast U.S.

Atmospheric rivers (ARs) are widely studied on the U.S. West Coast, as they produce almost half of the annual precipitation. In contrast, ARs in the Northeast have been studied considerably less, despite having larger IVT magnitudes. When AR events coincide with one another or occur consecutively, forming an AR cluster, there can be a larger impact. The purpose of this study is to create a 30-year (1988-2017) climatology of AR clusters in the northeast U.S., during the warm season (May-October), and observe the precipitation patterns associated with these clusters. The Northeast AR cluster climatology was gathered from a 30-year Northeast AR climatology created by Kaminski et al. (2023). Using HUC8 watershed codes and ERA5 hourly IVT, clusters were determined and further examined at 8 individual cities. Finally, daily precipitation data was gathered from NOAA NCEI for each of the selected cities.

Overall, the warm season features 65.4% of all the AR clusters in the 30-year climatology and they can be quite intense with IVT magnitudes sometimes greater than 1500 kg m^-1 s^-1. Within the warm season, the more northern cities in the Northeast experience AR clusters with higher IVT magnitudes but fewer ARs per cluster. In terms of precipitation, the inland cities feature a higher average amount of precipitation associated with AR clusters.