The Madden-Julian Oscillation's Influence on Continental U.S. Hurricane Landfalls

The Madden-Julian oscillation (MJO) has been documented in a variety of prior studies to significantly impact Atlantic hurricane activity through modulations in atmospheric conditions including vertical wind shear, mid-level moisture, vertical motion and surface pressure. This study extends this prior research by showing significant modulations in continental United States (US) hurricane landfalls by the MJO. We use an MJO reconstruction that extends back to 1905 combined with the canonical Wheeler-Hendon index since 1974 to show that the relationships that we document are robust over 100+ years of data. We find that US hurricane landfalls are more likely in MJO phases 1-4 (MJO enhanced convection is centered over Africa, the Indian Ocean, or the western portion of the Maritime Continent) and is less likely when the MJO is in phases 5-8 (MJO enhanced convection is centered over the eastern portion of the Maritime Continent, the western Pacific or the Western Hemisphere). Further analysis indicates that the highest likelihood for Gulf Coast landfall is in MJO phases 1-2 while East Coast landfall is highest in MJO phases 3-4. These differences appear to primarily be driven by longitudinal shifts in TC genesis as associated MJO-driven atmospheric signals propagate across the basin from west to east. Steering currents did not show significant differences between MJO phases.