Thorncroft and Hodges (2001) used automatic tracking techniques to identify coherent vorticity structures over West Africa and the tropical Atlantic. Their study indicated the existence of two dominant source regions, the first of which was found south of about 15°N in the rainy zone, with a track density maximum just offshore the West African coast. The second was located north of 15°N on the fringes of the Sahara.

The present study extends this analysis by considering the relationship between the storm tracks over West Africa and the Tropical Atlantic in more detail and includes an investigation of their interannual variability. In this analysis ERA40 data from the ECMWF for the entire period from 1958 to 2002 is used. Results show that the southern storm tracks provide systems that are able to proceed far out over the tropical Atlantic and often become important players for tropical storm development, whereas the northern storm tracks play a much less important role in the tropical Atlantic. This study includes analysis of the interannual variability of these systems, focusing particularly on tracks relevant for Atlantic Tropical Cyclones. This variability will be related to several large-scale signals, such as Atlantic SST’s, ENSO and Sahelian Rainfall Index.