Remote Interactions between tropical cyclones: The case of Hurricane Michael and Leslie's high predictability uncertainty

TL;DR

This study investigates how interactions between hurricanes Michael and Leslie influence Leslie's trajectory predictability, revealing that upper-level wind interactions and jet stream modifications significantly affect forecast uncertainty.

Contribution

It introduces a clustering approach to analyze tropical cyclone interactions and demonstrates how upper-level dynamics impact hurricane track predictability.

Findings

Cluster 1 accurately predicted Leslie's path towards Iberia.

Interaction between Michael and jet stream alters Leslie's trajectory.

Upper-level wind divergence influences cyclone steering currents.

Abstract

The study explores Hurricane Michael's impact on Hurricane Leslie's trajectory predictability using ECMWF and NCEP ensemble systems. A clustering method focused on tropical cyclones is used to identify potential paths for Leslie: Cluster 1 accurately predicted Leslie's direction towards the Iberian Peninsula, whereas Clusters 2 and 3 indicated a southern recurve near the Canary Islands. Analysis of potential vorticity and irrotational wind at upper levels showed a significant interaction between Michael, ridge, and trough across the jet stream from +12 h after initialization. Cluster 1 showed a stronger Michael promoting upper-level wind divergence greatest, modifying the jet stream configuration around the ridge and downstream. Alterations in the jet stream's configuration, functioning as a waveguide, propagated downstream, guiding Leslie towards the Iberian Peninsula. Clusters 2 and 3 indicated the trough's failure to incorporate Leslie, resulting in a recurve of the trajectory around the Azores anticyclone. This research enhances comprehension of the interaction between two tropical cyclones via synoptic Rossby wave flow. Moreover, the conceptual framework can aid operational meteorologists in identifying the sources of uncertainty, particularly in track forecasts under synoptic conditions analogous to those examined in this study.