What Drives Variability in Tropical Cyclone Landfall Patterns in the Eastern North Pacific? Environmental Drivers and Implications

In Mexico, Tropical Cyclones (TCs) are among the natural disasters with the greatest economic and social impact, including especially high death rates in the economically vulnerable southwest coastal states. Despite having the highest TC density in the world, Eastern North Pacific TC variability receives relatively little research attention. Previous work in this region has studied TC Activity and track densities modulated by different climate drivers such as ENSO, MJO, PDO, and the Central America Gap Winds. Research has yet to understand what drives variability in TC landfalls along Mexico’s west coast. This work examines how landfall counts variability depends on genesis and landfall probability (steering flow). We quantitatively decompose total landfall counts into spatial contributions from genesis location and landfall probability due to the steering flow. Applying this framework to IBTrACS and ERA5 reanalysis datasets, we conducted a monthly composite analysis to examine key environmental differences between high and low landfall probability years. Our results show that years with lower landfall rates actually exhibited a higher number of TC genesis during most months, indicating that variations in steering flow play a major role in landfall variability. In contrast, the high landfall years are characterized by a concentration of landfalls in Southwest Mexico primarily attributed to two factors: anomalous low-level westerlies in June and September and reduced Tehuantepec Gap Winds strength during October, resulting in anomalous northward steering flow augmenting landfall probability in the region. This study provides crucial insights into the atmospheric conditions that could produce a high landfall hurricane season, providing the foundation for improving subseasonal to seasonal hurricane landfall predictability.