Heavy rainfall during the third severe thunderstorm of the previous 24 hours. These storms were the result of cold air penetrating into the western Mediterranean over the last couple of days which led to the formation of a very slow moving cold pool. This cold pool started to extend southwards on the 1Sept12 creating warm and moist south-westerly air streams close to the central Mediterranean. During the 2nd and 3rd Sept 2012, a depression developed over Libya and continued to extend northwards merging with a wide low pressure system over northern Italy. This long area of low pressure across the central Mediterranean triggered the development of thunder clouds which, finding a very warm sea of around 29C (similar to tropical ocean temperatures) and with lots of available moisture, grew rapidly into large thunderstorms with heavy rainfall and strong wind gusts. The weather sounding showed lots of instability and wind shear. In fact, waterspouts (these photos are from various sources) had also developed during this last storm.