Near-equatorial tropical cyclogenesis challenges classical dynamical theory and presents an acute forecasting problem. Tropical Cyclone Senyar, which formed at 4.7°N in the Strait of Malacca in November 2025, offers a unique opportunity to examine how the Madden–Julian Oscillation (MJO), convectively coupled equatorial waves, and regional circulation combine to enable cyclone formation under weak planetary rotation.

This seminar will focus on Senyar’s multi-scale genesis pathway. The MJO provided a supportive intraseasonal envelope, but genesis occurred away from its convective center and maximum convergence. An equatorial Rossby wave sustained cyclonic vorticity, while successive convectively coupled Kelvin waves contributed to preconditioning and final spin-up. Mixed Rossby–gravity wave activity modulated meridional steering, helping guide the disturbance toward a favorable genesis location. Enhanced low-level convergence and vortex stretching were central to intensification.

These wave interactions operated within a background shaped by La Niña, a negative Indian Ocean Dipole, and a northward-displaced Intertropical Convergence Zone. Together, they strengthened the cyclonic shear between equatorial westerlies and the northeast monsoon and supported a moist environment with reduced vertical wind shear. The seminar will distinguish large-scale environmental support from the wave processes driving vortex development and discuss implications for anticipating rare near-equatorial cyclogenesis.

https://uw-edu-pl.zoom.us/j/99786293780?pwd=qtvoSpNaTaQpzxWYW03OYxoZcR04Cj.1