NSSL scientist studies Western Mediterranean flash floods

False color enhanced infrared image of the dual mesoscale convective systems along the eastern coast of Spain that produced flooding at Valencia and a tornado on the island of Menorca.

A chance meeting between NSSL and European scientists has sparked a research collaboration on the topic of flash floods. Chuck Doswell spent five months at the University of the Balearic Islands (UIB) studying heavy rain events in the Mediterranean from late 1995 to early 1996, with support from the government of Spain and the European community. A goal of this collaboration was to test a mesoscale numerical model as a potential operational tool in support of heavy precipitation forecasts.

The Western Mediterranean region is dominated by the relatively warm waters of the Mediterranean Sea and the complex terrain that surrounds it. Prior work by scientists at UIB had shown that most of the heavy precipitation episodes were associated with relatively strong synoptic scale weather systems. Earlier studies done at NSSL by Dave Stensrud and his collaborators had shown that mesoscale prediction models tend to perform best in situations with strong synoptic-scale signals and when dominated by topographic influences.

Three Western Mediterranean flash flood case studies were chosen for detailed study, and mesoscale numerical model simulations were attempted for each case. Results gave considerable optimism about use of mesoscale model forecasts as guidance for flash flood forecasting. Additional cases will be explored in an effort to increase scientific understanding of heavy rainfall and to explore further the application of mesoscale numerical model simulations in support of flash flood forecasting.