Assessment of recent rainfall anomalies in West Africa

Over the past few years, the Sahel experienced extremely heavy rains. The rainfall seasons in western Sahel have been the wettest in over 30 years. This paper examines the dynamics associated with the unusually wet West Africa with emphasis on the role of the dominant modes of variability. Rainfall amounts in many areas in the Sahel have been over 50% above the climatological mean and have been marked by highly frequent heavy rainfall episodes resulting from very active African wave disturbances. This has resulted in flooding and an increase in infectious disease outbreaks mainly cholera and malaria in many localities. These changes in rainfall patterns over West Africa mark a sharp contrast from the long term drying trend that started in the mid-70s and continued into the 80s and the 90s. More recently, the coupled ocean-atmosphere system featured circulation patterns more favorable to enhanced convection. The processes associated with the so called “rainfall recovery” in the Sahel are discussed and the ability of the NCEP coupled forecast system (CFS) to depict them is presented.