1. Centre de Recerca Aplicada en Hidrometeorologia, Universitat Politècnica de Catalunya, Barcelona, Spain
2. Department of Atmospheric and Oceanic Sciences, McGill University, Montreal, Quebec, Canada
3. School of Meteorology, and Center for Analysis and Prediction of Storms, University of Oklahoma, Norman, Oklahoma
4. Center for Analysis and Prediction of Storms, University of Oklahoma, Norman, Oklahoma