The Role of Guinea Highlands Convection on Tropical Cyclogenesis

Previous work has suggested that potential vorticity (PV) generated by convection in the vicinity of the Guinea Highlands is important for influencing the likelihood that an African easterly wave (AEW) will be associated with downstream tropical cyclogenesis. The PV structure of AEWs is determined by a combination of processes that occur upstream over West Africa and those that occur in the vicinity of the Guinea Highlands, especially those associated with the coherent diurnal cycle of convection. We will explore the interaction of this diurnal cycle with an approaching AEW. Tropical Storm Debby (2006), a surprising developing AEW during the 2006 NAMMA (NASA African Monsoon Multidisciplinary Analyses) period, is looked at as an ideal case of the merging of PV between the Guinea Highlands and a weak approaching AEW. We will compare the evolution of the Debby-precursor with one that was similar but did not develop in order to shed light on the processes that influence whether an AEW will develop or not.