Revisiting the connection between African Easterly Waves and Atlantic tropical cyclogenesis

Abstract

AbstractAfrican Easterly Waves (AEWs) are the primary precursor for Atlantic tropical cyclones (TCs). We update the statistics on this relationship using reports from the U.S. National Hurricane Center. Sixty‐one percent of TCs originate directly from AEWs. Indirectly, AEWs are implicated in the formation of an additional 11% of TCs. AEW activity is quantified by eddy kinetic energy (EKE). The correlation between seasonal mean EKE and TC genesis is maximized in the lower troposphere below the southern AEW storm track, instead of where the canonical AEW is maximized. Therefore, midlevel AEW activity is a poor predictor of TC genesis, whereas its lower tropospheric circulation exerts stronger control. In most seasons, AEW activity is supercritical, and therefore, EKE is only a controlling factor in seasons when the low‐level EKE is weak. Predicting 1000–800 hPa EKE below the southern AEW track may be useful for seasonal TC prediction.