An EF3 Multivortex Tornado over the Ionian Region: Is It Time for a Dedicated Warning System over Italy?

Abstract

he possibility offered by the Internet to share pictures of tornadoes, and the storm-report archiving in the European Storm Weather Database, have made it apparent that the occurrence of tornadoes over Europe has been underestimated. Together with weak waterspouts and tornadoes, large and intense vortices are occasionally observed. Among these, an EF3 multivortex tornado with a path width of some hundreds of meters affected southeastern Italy on 28 November 2012, causing one casualty and estimated damage of ?60M to the largest steel plant in Europe. A tide gauge positioned near the location of tornado landfall and a vertical atmospheric profile available a few hours later near the affected region represent unique sources of information for these events in the Mediterranean. During its transit across the port of Taranto, a waterspout, which was to become the tornado, was observed to have induced a sea level rise of about 30 cm. The supercell responsible for the tornado developed from convective cells triggered by orographic uplift over the Apennines. The 0?1-km wind shear was exceptional in comparison with other Italian tornadoes, and was remarkable in comparison with U.S. events as well. Other indices for severe convection diagnosis also showed extremely high values. The occasional occurrence of events with similar or stronger intensities over Italy emphasizes the need for the Distributed National Weather Service?which will integrate Italian meteorological institutions under one agency and is currently under development?to devise a warning system dedicated to the monitoring and prediction of severe convective events.