Preliminary evaluation of a short-range ensemble prediction system over western Mediterranean

A generation of a short-range ensemble prediction system, based on a set of mesoscale models with different subgrid-scale physic schemes and two different initial conditions, is developed, providing flow-dependent probabilistic forecasts by means of predictive probability distributions over the Western Mediterranean. A ten members short-range ensemble forecast system has been constructed over western Mediterranean area as a result of combining two different initial conditions from global models and five different physics configurations of the non-hydrostatic Mesoscale Model (MM5, version 3). The simulations obtained from this ensemble have been investigated during October 2006 period. An overview of the mean model performance and forecast variability, together with an evaluation of the ensemble accuracy, by means of comparison between the ensemble system and observations is provided. Calculations of the ensemble probability distribution functions for precipitation are displayed, providing explicit information on ensemble forecast uncertainty and constituting one of the major advantages of the ensemble methods over deterministic forecasting. The quality and value of precipitation forecasts have been evaluated against Spanish Climatic Network. The verification scores exhibit hopeful results encouraging the extension of this preliminary research to other verification periods and studying cases. ------------------------------------