Dynamic Forcing Behind Hurricane Lidia’s Rapid Intensification

Abstract. This study examines Hurricane Lidia’s rapid intensification (RI) in the understudied northeastern Pacific, focusing on its interaction with an upper-level trough. Using IFS-ECMWF ensemble forecasts and ERA5 reanalysis, we analyze the large-scale dynamical mechanisms driving Lidia’s intensification. Results show that the trough played a crucial role in promoting RI by enhancing synoptic-scale ascent, upper-level divergence, and eddy flux convergence. In the higher-intensification ensemble group, stronger Trenberth forcing emerged prior to RI onset, suggesting a causative role in preconditioning the storm environment. This dynamical forcing likely triggered latent heat release, which in turn modified the upper-level potential vorticity structure and contributed to a subsequent reduction in vertical wind shear. In contrast, the lower-intensification group exhibited weaker forcing, higher shear, and a lack of sustained ventilation. These findings highlight the importance of diagnosing early dynamical triggers for RI, particularly in regions where operational access to high-resolution models is limited. This approach provides a cost-effective framework for anticipating RI using ensemble-based diagnostics and could serve as a valuable forecasting tool in data-sparse areas such as the Pacific coast of Mexico. Future studies should combine this large-scale methodology with high-resolution simulations to better capture storm-scale processes and validate multi-scale interactions in RI events.