Lightning in the eastern Alps 1993-1999, part I: Thunderstorm tracks

Abstract. Thunderstorm tracks in the eastern Alps for the summers of 1993-1999 are investigated based on lightning data. The tracking method consists of three steps. Step one filters weak storms. Step two fixes the positions of the single cells, which are then connected. The wind at 700hPa, which approximates the steering level of the thunderstorms, is used to distinguish between six weather patterns. Maps including all discovered tracks are discussed for each flow type. While locations from which thunderstorms originate are almost similar, the track patterns are distinct for each flow type. Main initiation areas are mountain ranges of moderate altitude (≈2.5km MSL) from where most of the tracks lead into flat areas.