Subseasonal variability of North American tropical cyclone landfalls and phase transitions over the Atlantic coasts

Abstract Tropical cyclones (TCs) and subtropical cyclones (STCs) can bring very severe disasters to coastal areas and nearby inland regions when they move along the coastlines or make landfalls. Moreover, their cyclone phase transitions (PTs) may lead to substantial changes in their structures, intensities and tracks. Hence, near-coast PTs pose additional challenges in disaster preparedness. The current study shows that the North American Subseasonal Variability (NASV) have substantial modulation of landfalls and near-coast PTs at all Atlantic coasts of the U.S. and Canada. When the anomalies associated with strong northward propagating NASV are located at specific regions, the Atlantic coasts of interest experience significantly different landfall rates, landfall intensities or PT percentages. Thus, our findings imply possibilities of improving predictions of landfalls as well as near-coast PTs on both subseasonal and synoptic timescales. The results also suggest that NASV may have contributions from the convection anomalies over the western tropical Pacific.