Meteorological Forecasting

Meteorological forecasts offer the potential to extend the time available for decision-making in hydrological applications. In addition to the general weather forecasts provided to the public, more specialised products and services are usually available to expert users, including the raw ensemble model outputs for use in flow forecasting models. The main meteorological forecasting techniques consist of nowcasting, Numerical Weather Prediction models (including General Circulation Models) and statistical methods, which are typically used at seasonal lead times. This chapter provides a brief introduction to the key concepts and limitations behind these approaches and then discusses the practical aspects of using rainfall and temperature forecasts operationally in hydrological models. The topics discussed include dynamic, weather pattern matching and statistical downscaling techniques, statistical post processing, mechanisms for forecast delivery, and forecast verification.