Although there exist many scenario composing methods, computational support has not been provided enough for scenario design. This paper proposes a method for supporting design of new forecasting scenarios using a causal network and a storyline. This method supports creating storylines, which are assumptions of sub scenarios, as well as composing scenario text based on the causal networks and the storylines. A prototype system is developed for supporting the proposed method. The results of case study illustrated that generating the storylines of a scenario are systematically supported by using the causal network and that composing scenario text is supported by detailing the causal network and the storylines.
