Both 1995 and 1996 showed active tropical cyclone activities over the tropical eastern Atlantic, each with six named storms. However, both 1994 and 1997 had very inactive seasons over that region with only one named storm developed in August 1994.
Satellite longitude-time (Hovmoller) diagrams of cloudiness over the tropical Atlantic and northern Africa, along with time series and monthly means of rawinsonde data over western African and the eastern Caribbean stations, were used to compare the 1994 1995, 1996 and 1997 hurricane seasons. Global model analyses were also used for the comparison over the Atlantic oceans.
No significant difference in the vertical wind shear was indicated over the tropical eastern Atlantic and western Africa during the month of August of those four years. The rawinsonde data from western Africa indicated that the inactive years were characterized by more stable environment that suppressed the development of deep convection. This result agrees with the mean upper level large-scale circulation from the global model analyses that show stronger Hadley-like divergent flow over the tropical eastern Atlantic for August of 1995 and 1996. Walker- like upper level flow with convergence over that region was found for August of 1994 and 1997.