This study introduces the development of the Tracking Algorithm for Mesoscale Convective Systems (TAMS), an algorithm that allows for the identifying, tracking, classifying, and assigning of rainfall to mesoscale convective systems (MCSs). TAMS combines area-overlapping and projected-cloud-edge tracking techniques to maximize the probability of detecting the progression of a convective system through time, accounting for splits and mergers. The combination of projection on area overlapping is equivalent to setting the background flow in which MCSs are moving on. Sensitivity tests show that area-overlapping technique with no projection (thus, no background flow) underestimates the real propagation speed of MCSs over Africa. The MCS life cycles and propagation derived using TAMS are consistent with climatology. The rainfall assignment is also more reliable than with previous methods as it utilizes a combination of regridding through linear interpolation with high temporal and spatial resolution data. This makes possible the identification of extreme rainfall events associated with intense MCSs more effectively. TAMS will be utilized in future work to build an AEW–MCS dataset to study tropical cyclogenesis.

Satellite rainfall estimates reveal a consistent rainfall maximum off the West African coast during the monsoon season. An analysis of 16 years of rainfall in the monsoon season is conducted to explore the drivers of such copious amounts of rainfall. Composites of daily rainfall and midlevel meridional winds centered on the days with maximum rainfall show that the day with the heaviest rainfall follows the strongest midlevel northerlies but coincides with peak low‐level moisture convergence. Rain type composites show that convective rain dominates the study region. The dominant contribution to the offshore rainfall maximum is convective development driven by the enhancement of upslope winds near the Guinea Highlands. The enhancement in the upslope flow is closely related to African easterly waves propagating off the continent that generate low‐level cyclonic vorticity and convergence. Numerical simulations reproduce the observed rainfall maximum and indicate that it weakens if the African topography is reduced.

An African easterly wave (AEW) and associated mesoscale convective systems (MCSs) dataset has been created and used to evaluate the propagation of MCSs, AEWs, and especially, the propagation of MCSs relative to the AEW they are associated with (i.e., wave-relative framework). The thermodynamic characteristics of AEW-MCS systems are also analyzed. The analysis is done for both AEW-MCS systems that develop into tropical cyclones and those that do not to quantify significant differences. It is shown that developing AEWs over West Africa are associated with a larger number of Convective Cloud Clusters (CCCs; squall line-type systems) than non-developing AEWs. The MCSs of developing AEWs propagate at the same speed of the AEW trough in addition to being in phase with the trough, whereas convection associated with non-developing AEWs over West Africa moves faster than the trough and positioned south of it. These differences become important for the intensification of the AEW vortex as this slower-moving convection, i.e. moving at the same speed of the AEW trough, spends more time supplying moisture and latent heat to the AEW vortex supporting its further intensification. An analysis of the rainfall rate (MCS intensity), MCS area and latent heating rate contribution reveals that there are statistically significant differences between developing AEWs and non-developing AEWs, specially over West Africa where the fraction of extremely large MCS areas associated with developing AEWs is larger than for non-developing AEWs.

The topography of eastern Africa, namely, the Ethiopian Highlands and Marrah Mountains have been shown to play a key role in the genesis of African Easterly Waves (AEWs) through convective initiation in that region. Topographic influences on the African Easterly Jet, evolution and energetics of AEWs, and rainfall production across northern tropical Africa are examined here. The Weather Research and Forecasting model is employed to simulate the climate over a 60-day period for three years (2004, 2005, and 2006) for three cases with varying topography: realistic, half-height, and no topography. An energetics analysis for the resulting AEWs reveals that wave development by barotropic and baroclinic processes weakens when topography is flattened. These results show that topography in Africa plays a significant role in the wave development as they propagate westward, not only in their initiation over East Africa.