The temperature contrast between the Sahara Desert and the Gulf of Guinea causes the jet to form to the north of the monsoon trough.
During January, the African easterly jet lies at 3,000 metres (9,800 ft) above sea level at five degrees north latitude.
[1] From June into October, the thermal low over northern Africa leads to a low-level westerly jet stream to the south of the Intertropical Convergence Zone.
These instabilities, particularly in the presence of moist-convection, cause intense lower-layer cyclonic vortices at the northern flank of the jet.
When the jet is south of normal during the peak months of the Atlantic hurricane season, tropical cyclone formation is suppressed.