Exploring the Usability of Probabilistic Weather Forecasts for Water Resources Decision-Making in the United Kingdom

Abstract

Abstract Over the last two decades, probabilistic weather forecasts have been developed to quantify the uncertainties inherent in modeling the climate system. The skill of these forecasts has steadily increased, but the question of whether they are usable for water resources management remains open. The interdisciplinary study described in this paper combined a modeling approach with qualitative methods to identify technical and nontechnical factors that enhance or constrain the usability of probabilistic weather forecasts for reservoir management, using a case study of drought management decision-making by a water supply company in northwestern England. The modeling approach calibrated and applied probabilistic medium- and extended-range precipitation forecasts from the European Centre for Medium-Range Weather Forecasts (ECMWF) to a simplified water resources system to study the technical quality of the forecasts that, in principle, could have informed management decisions during a drought event in 2010. The qualitative approach comprised initial semistructured interviews with water managers and regulators and follow-up discussions using the model experiment results to elicit further insights into the potential for incorporating probabilistic forecast information into decision-making processes. The technical analysis showed that even these postprocessed forecasts did not have skill beyond the medium range; this constrains the type of management decisions the forecasts can inform. Regulatory frameworks and attitudes to risk in the water sector also inhibit the take-up of probabilistic forecasts for drought management decisions owing to the high stakes of such decisions and considerations spanning entire water resource zones.