Kelvin Waves and Tropical Cyclogenesis in a Lagrangian Framework

Recent work has shown that tropical cyclogenesis is favored 0–3 days after Kelvin wave passage. Other studies have shown the utility of a Lagrangian framework for identifying the recirculation of moisture within easterly waves. This recirculation ultimately leads to tropical cyclogenesis within the wave's “pouch.” This study examines the role of the equatorial westerlies from Kelvin waves in helping to close the Lagrangian circulation. The vertical tilt of Kelvin waves results in these westerlies reaching mid-levels about 3 days after the convection passing, which may explain the delay between Kelvin wave passage and cyclogenesis. Given that Kelvin waves frequently circumnavigate the globe, these results may provide a framework for long range tropical cyclogenesis forecasting.