Finnish Meteorological Institute, Helsinki - Finland
During the evening of 13 of September 1997 two tornadoes occurred in the area of Poh-janmaa, about 10 km inland from the west coast of Finland. Based on a damage survey, both tornadoes were of F2 intensity. The damage paths were small, only 700 and 500 m long and 130 and 100 m wide. It seems that suction vortices caused the most intense dam-age. The tornadoes were associated with a thunderstorm that formed along a rapidly moving cold front. Radar observations reveal that a narrow rainband developed parallel to the frontal surface. Near the tornado locations the highest radar reflectivity was 45 dBZ and the thunderstorm echo top reached 11 km. Line echo wave pattern and highest echo top were observed in the close proximity of one of the two tornadoes.
The most intense tornado in Finland during the last few years occurred in the afternoon of 12 June 1998 in Mikkeli. Damage survey indicated that this cyclonic vortex was of F3 in-tensity. The damage path was 8.6 km long and its maximum width was 330 m. This tor-nadic thunderstorm developed in a warm sector near an almost stationary warm front. The tornado formed in the early stage of the thunderstorm lifecycle, only 30 minutes after the first radar reflectivity echo. After the formation of the tornado, the thunderstorm showed many features characteristic of supercell storms. Still, the diameter of the 15 dBZ reflectivity contour was only 18 km. Comparison of the emergency reports along the path of the tornado and simultaneous radar reflectivity at different times show that the tornado was situated at the right rear flank of the storm.