On the 2017 rainy season intensity and subsequent flood events over West Africa

We analyze here the intensity of the 2017 rainy season in West Africa with particular focus on the characteristics of the precipitation events as well as the propagating Mesoscale Convective Systems (MCSs). This is to provide a context for the multiple flood events that occurred in most West African capital cities during 2017. The analysis reveals that the whole of West Africa experienced above normal precipitation during June-September compared to the last 35 years as a consequence of increased overall intensity of the monsoon season. Specifically, the flood events recorded in Conakry (Republic of Guinea), Freetown (Sierra Leone), Kidal (Mali), Niamey (Niger), San Pedro (Cote d’Ivoire) and Port Harcourt (Nigeria) resulted from the occurrences of more frequent and more intense precipitation events than usual. In Lagos (southwestern Nigeria) and Accra (southern Ghana) however, the recent flooding seems to be linked to more extended length of consecutive wet days linked to more intense and larger Mesoscale Convective Systems (MCSs) propagating across the region. Since numerous climate projections over West Africa suggest the situation may be exacerbated in future climate, stronger disaster management, early warning systems and adequate flood-control infrastructures are needed to combat the consequences of these intense extreme precipitation events fuelled by the changing climate regime.