Speaker: Dr. Victor Homar (University of the Balearic Islands, Spain)
Topic: "Severe weather in the Western Mediterranean: processes and predictability analysis. From MEDEX to HyMeX"
Room: 529 Walker Building (refreshments served)
Time: July 20, 2016 10:00am to 11:00am
Abstract: Mediterranean high-impact weather comes in a variety of forms. Besides the "severe weather" definition universally adopted from the United States atmospheric community, the Mediterranean possesses an additional meteorological threat in the form of torrential rainfall and catastrophic flooding. After more than 50 years of research on atmospheric predictability, enormous progress has been done for medium range forecasts (synoptic and planetary scales). However, operational offices still struggle nowadays to issue reliable yet useful forecasts of hazardous meteorological phenomena. The battle against chaos for socially valuable forecasts at longer lead times has two main fronts: on the one side, improving the representation of the atmospheric state in our forecasting systems; and on the other, coping with the inherent uncertainty associated with any forecasts. Conversely, ensemble generation techniques for the short range imitating large scale methods fall short in encompassing the subsynoptic variability and mesoscale error growth. In this context, fast growing modes and dynamical sensitivity methods fail in providing useful information for ensemble generation and observation targeting decision-making. Conclusions derived from research conducted during the MEDEX and HyMeX Mediterranean projects along these basic objectives will be presented. Numerical experiments help identify the main physical mechanisms acting on the generation of severe phenomena, and persistently highlight the primary role of the geography of the Mediterranean and the usefulness of the ingredients-based conceptual models. Also, we present the singularities the region presents to benefit from the use of 4DVAR techniques. Discussion about these topics will be encouraged and promoted in the talk.