1. HRV (70-100%)IR10.8 (Tb<240K) HRV (70-100%) radar Zmax > 35dBz HRV cloud (HRV,HRV,IR10.8) radar Zmax > 35dBz (CC+CG) 10-minute lightning data (CC+CG) Simultaneous satellite and radar data The radar images overlaid on satellite images are always interpolated in time (using displacement vector fields) to the satellite ‘European time’ (nominal + 10 minutes). (P. Németh) The parallax effect is not corrected. CC: cloud to cloud flashes, CG: cloud to ground flashes Satellite, radar and lightning data

2. Lightning In the updraft part of a cell many collisions happen between cloud particles, and the particles may became electrically charged. The positive and negative charges accumulate in different parts of the clouds. The generated poles cause discharges: first intra-cloud then cloud-to-ground flashes of lightning. The highest number of discharges occur in the closed ambience of the overshooting top.

3. Developing stage -- single cell The following features characterize the developing of a single cell: The developing stage lasts 5 to 10 minutes A distinct single updraft is prevailing The diameter of the cell is between 2 and 8 km At the end of this stage lightning is most intense Lightning in the upstream part of Cb/MCS

4. Lightning activity was extremly high in this MCS, more then 1000 CC (cloud to cloud) flashes were detected per 10 minutes between 6-11UTC. Between 10:10-10:20UTC almost 8000 CC flashes were detected.

5. HRV (70-100%) HRV (70-100%) Radar Zmax (>35dBz) IR10.8 (<240K) HRV cloud Radar Zmax (>35dBz) 10min lightning

12. Parallax shift Overshooting top

15. High radar reflectivities close to overshooting tops The majority of lightnings are close to overshooting tops Cold rings, cold U shape Overshooting top

16. Cold rings, cold U shape Overshooting top

17. Cold rings, cold U shape

18. Overshooting top

23. Plume Overshooting top CC CG

26. Asymmetric bow echo

27. After this less flashes Radial Ci Overshooting top Bow echo

28. The number of the flashes decreased at about 11UTC and further decreased after 12UTC. The system became less active.