Besides the transition between the two processes being very well depicted in satellite images, the stages of the development are also contained in the relevant numerical parameters.
This was a rather classical process of cyclogenesis. It is very well depicted in the PV field with height of PV=1 unit coming down to 500 hPa. Temperature advection shows a typical distribution with the warm advection in the cloud head and cold behind. The cyclone developed near the Bay of Biscay and moved across south France and north Spain. At the time when development in the Bay of Biscay took place, there were only low clouds, with no sign of development in the Mediterranean.
The process in the Mediterranean was triggered by the vorticity advection in the exit region of the southwesterly jet. This transition between the two systems was well depicted in almost all numerical parameters, especcially vorticity and vorticity advection, but also temperature advection. The old cyclone stayed over south France and was dissipating, whereas the new one developed in the Mediterranean near the Bay of Biscay.
The new cyclone developed further, moving towards northeast. When moving towards the Adriatic, two low centres developed within the cyclone. The first cyclone, the one coming from the Bay ogf Biscay completely dissapeared, at one stage the remnants of the cloud band joined the cloud head of the new developed cyclone.