Understanding the Role of Eddy Vorticity Fluxes on Rapid Intensification of Hurricanes Irma and Michael

The relationship between rapid intensification and environmental forcing is investigated for Hurricane Irma (2017) and Hurricane Michael (2018) using the Hurricane Weather Research and Forecasting (HWRF) model . Despite different environments, both Irma and Michael became major hurricanes that made landfall in the United States. Hurricane Irma rapidly intensified in an environment with weak vertical wind shear. In contrast, Hurricane Michael rapidly intensified in an environment of strong vertical wind shear. While Irma was predicted to intensify in a favorable environment, the forecast for Michael was more challenging because tropical cyclones typically do not rapidly intensify in similar conditions. The angular momentum budget is compared for these two hurricanes to identify similarities and differences in the pathways to intensification in varied environments. The eddy radial vorticity flux term is a focal point as previous studies have found it to have a significant role in intensity change and vortex spin up in sheared tropical cyclones.