Cyclone Families, Atmospheric Rivers, and Hydrometeorological Extremes over the Eastern U.S.

Atmospheric rivers (ARs) have emerged as a focus of many global hydrometeorological studies and applications. These corridors of enhanced integrated water vapor (IWV) and IWV transport (IVT) that may accompany extratropical cyclones across many locations across the globe are linked to heavy and extreme rainfall events that can produce societal impacts in association with extreme winds, avalanches, floods, flash floods and debris flows, and shallow landslides. The impacts of ARs are often exacerbated owing to both the intensity and duration of orographic precipitation associated with strong water vapor flux perpendicular to lifting mechanisms such as topographic barriers or stalled frontal boundaries.

This study focuses on cyclones familes and their ARs, such as those that might occur in association with “mesoscale frontal waves” or back-to-back storms that occur in within a short duration of time (e.g., <5–7 days). Whereas a single cyclone and AR may only produce beneficial and marginal high-impact weather, a pair or series of cyclones and ARs are capable of producing more severe impacts (e.g., flooding, landslides) owing to preconditioning of hydrological conditions. While many examples exist of ARs and their impacts over the western U.S. (such as the series of ARs that produced hydrometeorological extremes in California in February 2017), this study focuses on ARs and their impacts over the eastern U.S. (such as the series of ARs that produced the “Great New England Flood of 1936” and flooding more recently in October 2017).