Winter thunderstorms in Israel: A study with lightning location systems and weather Radar

A study of the morphology and evolution of winter thunderstorms in Israel and over the eastern Mediterranean was conducted during the 1995-96 winter season. Electrically active cells were analyzed by combining data from weather radar and an operational lightning positioning and tracking system. This enabled the identification of reflectivity features of electrically active cells, and tracing of the spatial and temporal evolution of thunder- storms. The results show that, in winter, rain clouds became thunderclouds if their echo top was higher than 6500 m (at a temperature level colder than -30°C), provided that the reflectivity at the level of the -10°C isothern was larger than 35 dBZ. The period between the first radar echo and the first detected lightning flash (probably a ground flash) was found to be 10-15 min, a period at which the top of the 40-dBZ echo was located higher than the -8°C level.