Hurricanes Ivan, Jeanne, Karl (2004) and mid-latitude trough interactions

The evolution of a strong midlatitude trough and its relationship to three Atlantic hurricanes (2004) is examined with the Navy Operational Global Atmosphere Prediction System (NOGAPS) singular vectors (SVs). The extratropical transition of Ivan over the mid-Atlantic US is identified as crucial to the development of a large cut-off low over the Canadian Maritimes. An equatorward extension of this trough dynamically interacted with the “looping” Hurricane Jeanne, aided in intensification, and nearly towed the system across the Atlantic. Similarly, Hurricane Karl rapidly recurved ahead of the trough, underwent a positive trough interaction and intensified before finally transitioning to an extratropical system.

Singular vector diagnostics have been shown useful for understanding both midlatitude and tropical cyclone phenomena. The SV calculations of perturbation energy growth, optimized for the regions centered upon the storms, are based upon the 48-hour forecast trajectories from NOGAPS. For all three hurricanes, Ivan, Jeanne and Karl, the SVs show large perturbation energy growth well away from each respective cyclone center, reflecting the influence of the mid-latitude trough. In conjunction with mesoscale model trajectory analysis, the SV perturbation areas match up well with potential vorticity advection directly impacting each tropical cyclone. SV analysis provides a useful tool for understanding TC/midlatitude interactions, crucial to accurate forecasting of looping tracks, trough interactions, and extratropical transitions.