During FASTEX, 19 frontal cyclones at different stages of development have been sampled using airborne facilities (dropsondes released every 70 km and 2 dual-beam Doppler radars). These facilities allow to access the dynamic and thermodynamic characteristics of the phenomena and the involved multi-scale processes. Previous studies conducted at the CETP on a bent-back warm front case of FASTEX (Intensive Observing Period 16) demonstrated the crucial role played by specific mechanisms in the intensification of the cyclogenesis (instability mechanisms, coupling between lower and upper troposhere, control by environmental deformation, importance of vorticity stretching, role of ice sublimation...) The present study attempts to evaluate the degree of generality of these results. For this purpose, 6 cases at different stages of development are investigated. This study is based on the estimation of diagnostic parameters at mesoscale, such as production of vorticity, potential vorticity and moist potential vorticity, energetic conversion, and impact of cyclogenesis on the environment in terms of momentum, heat and moisture budgets. All these points will be discussed in detail in the presentation.