From the measurements of the neutron monitors world network in the period 1996–2018, 31 strong Forbush decreases (5%) were identified that satisfy the accepted event selection criterion. The superposed epoch analyses is used to determine the consistent spatial distributions of the solar wind parameters and the decrease in cosmic ray density. It has been established that the contributions of the formation mechanisms of the Forbush decrease differ greatly in two groups of events. The difference may be since the formation of the Forbush depression in one group occurs in the frontal part, and in the other group in the peripheral part of the disturbance.