Developing and non-developing African easterly waves and large-scale environment over the eastern Atlantic

It well documented that about half of the tropical cyclones (TCs) that develop over eastern Atlantic basin are associated with African easterly waves (AEWs) and the vast majority of hurricanes develop in association with AEWs. On average, about 50-60 AEWs per year develop and cross the western coast of the continent. While AEWs are important precursors for TC-genesis, the great majority of AEWs that develop over Africa and crosses the continent do not develop into TCs. Studies suggest AEWs that develop into TCs tend to be associated with intense convection and are characterized by high relative vorticity, while non-developing AEWs are weaker and associated with less intense convection. However, our preliminary analysis shows that most of the AEWs that do not develop into TCs are as intense (measured by their maximum vorticity at the center) as those that develop, suggesting intensity of an AEWs at the western coast of Africa is not an adequate indicator of a developing and non-developing AEW. In this presentation we will present the details of this using dynamic and thermodynamic measures that compare developing and non-developing AEWs.