Waterspouts in the Eastern Adriatic from 2001 to 2013

One step toward improving our understanding of all the possible factors and environmental features that are related to waterspout formation is to establish continuous data collection and to provide a preliminary climatology of waterspouts in a region. A waterspout survey was launched on the official Web site of the Croatian Meteorological and Hydrological Service during late spring 2011. This survey helped create an extensive waterspout database, which recorded a total of 359 waterspout events from 2001 to 2013. Because most reports regarding waterspouts were obtained from unofficial sources, we underline the need for new ways to observe relatively short, rare and spatially limited weather events such as waterspouts. The analysis of the collected data in this work includes the spatial and temporal distribution of the waterspout events per year, season, month and time of day. “Non-thunderstorm” and “thunderstorm” waterspouts were separated, and the absolute frequencies of five synoptic types that were relevant to waterspout development are shown. Finally, the thermodynamic environment was analyzed with the help of radio-sounding data. The results show that waterspout events are equally distributed along the eastern part of the Adriatic coast. However, an evident connection exists between the number of spotted events and the locations of more densely populated areas, i.e., big towns or tourist destinations. Waterspouts are more frequent during the summer months, especially during August, and 51.5 % of the recorded events were related to thunderstorms. Most of them were spotted during the day, whereas only two were spotted during the night; waterspouts developed more often during the morning hours. The synoptic environment dominated by a southwesterly flow has proven to be the most supportive for the development of waterspouts.