Customer oriented warning systems

This study presents a theoretical analysis of the relationship between a warning organisation (issuer) and the users (addressees) of these warnings, in the field of weather forecasting. Warnings are based on probabilistic forecasts emanating from an Ensemble Prediction System, or from any system delivering a diagnostic expressed in term of probabilities. The addresse is characterized by the three key questions usually raised in risk analysis: What is the value at risk? How likely is a loss?, and what are the consequences, i.e. what happens under the course of actions available to him. Perspective of the addressee and the issuer are then linked together to develop a theory of optimal warning thresholds, enabling a qualitative translation of the issuer’s performance into efficiency by the addressee