The higher the category the more ferocious the storm and the damages to population and land can be positively catastrophic. The jet arises as a result of the reversed lower-tropospheric temperature gradient over western and central North Africa due to extremely warm temperatures over the Saharan Desert, in contrast with substantially cooler temperatures along the Gulf of Guinea coast. The waves move generally toward the west, in the lower tropospheric tradewind flow across the Atlantic Ocean. They are first seen usually in April or May and continue until October or November. On average, about 60 waves are generated over North Africa each year, but it appears that the number that are formed has no relationship to how much tropical cyclone activity there is over the Atlantic each year.
Warm waters are necessary to fuel the heat engine of the tropical cyclone.
An atmosphere which cools fast enough with height such that it is potentially unstable to moist convection. It is the thunderstorm activity which allows the heat stored in the ocean waters to be liberated for the tropical cyclone development. Dry mid levels are not conducive for allowing the continuing development of widespread thunderstorm activity. For tropical cyclogenesis to occur, there is a requirement for non-negligible amounts of the Coriolis force to provide for near gradient wind balance to occur. Without the Coriolis force, the low pressure of the disturbance cannot be maintained.