Measurement systems on tower worked normally. A major precipitation system impacted the Meck Island during 22:11 (August 11) and 02:24 GMT (August 12) which gave a total of 67.2 mm of rain. Because of the storm the tethered balloon flight of 23:00 GMT was cancelled. Tethered balloon flights were carried before (20:00 GMT) and after (05:00 GMT) the storm. An additional flight was scheduled for 08:00 GMT (August 12). Before the storm the mixed layer height was about 400-500 m and potential temperature averaged between 299-300 K. Two hours after the storm the mixed layer height reached ~ 200 m and the potential temperature averaged 297-298 K. At the surface, calm conditions prevailed after the storm but wind speed in the layer 600-1000 m above the surface reached about 10 m per s. Such relative strong winds persisted throughout the evening. Also, the atmospheric column extending from the surface to 300 m was wet (specific humidity around 18-19 g per kg) but moisture levels aloft ( > 300 m) were low (< 14 g per kg). Figures for tethered balloon flights are saved on the enclosed diskette.