Impact based forecasts and warnings (IBFW) combined information about the potential consequences (impacts) of weather events with the estimated probability of them occurring. In representing IBFW ordered verbal categories such as low, medium and high may be used to classify both probability and impact severity. However, there has to date been limited exploration of how these categories are interpreted in the context of IBFW. While work in the social and behavioural sciences suggests that there can be variability in interpretation of verbal representations of probability, such as those used in IPCC reports, statements about impact severity – where numeric estimates may not be as easily attached to descriptions – remain under-investigated. In regionally representative survey with n > 1500 members of the public in England, UK, we asked participants to indicate on sliders how they would interpret a series of descriptors of likelihood (0=will definitely not happen,100=will definitely happen) and impact severity (0=not serious at all, 100=very serious) related to severe weather. Examining mean, median and distribution of responses for each verbal likelihood and impact descriptor we find that while descriptors indicating a middle point (i.e. medium, moderate) tended to elicit judgements around the central point of the scale for both impact and likelihood statements, there was overall less consistency around phrasing intended to denote low and high categories. For impact statements, we observe overlap between ‘very low’ (mean=33, median=26) and ‘low’ (mean=34, median=28) as descriptors. Catastrophic and extreme were interpreted to denote the highest level of impact, though in both cases mean and median ratings of impact seriousness were below 75 with indication of wide variability in interpretation. For likelihood, we find that only the descriptor ‘high’ elicited an estimated likelihood above 60. Surprisingly phrases that may be intended to denote very high likelihoods (‘expected’) or certainty/near-certainty (‘observed’) received mean interpretations close to the centre of the scale. Taken together our findings suggest that while terms typically associated with mid-points may be understood as intended, gaps between communicator and recipient may occur when discussion events with very low and very high likelihood. We discuss potential approaches to addressing this, including providing numeric values with likelihood descriptors and avoiding terminology where the greatest gaps between intention and interpretation may occur.

How to cite: Taylor, A., Summers, B., and Jenkins, S.: Describing likelihood and impact in impact-based forecasts: What’s likely? What’s severe?, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-539, https://doi.org/10.5194/ems2025-539, 2025.

Enhancing user communication is a central goal of the RainBoW (Risk-based, Application-oriented and INdividualizaBle Provision of Optimized Warning Information) programme, which encompasses the development of the new weather warning system for the German Meteorological Service (Deutscher Wetterdienst, DWD). A clear understanding of issued weather warnings is essential for enabling both professionals and the general public to take appropriate action in affected areas. To support this, future warnings by the DWD will increasingly focus on impact information. Crowdsourced data, which reflects how users perceive specific weather events, offers a rich and valuable resource for improving this communication.

In this study, we focus on the hazards of wind gusts, which are among the weather elements with the greatest impact on infrastructure and society. To assess the severity of such events, we propose an impact proxy for Germany, derived from crowdsourced data collected through the Warnwetter App — the official weather app of the DWD. The app allows users nationwide to report their weather interpretations, providing a broad representation of the population’s exposure to weather events. Specifically, for wind gusts, users can choose from five predefined severity levels, ranging from "weak wind" to "severe storm".

We combine these crowdsourced reports (total number of roughly 55k) with meteorological ensemble model forecast data (ICON-D2-EPS) and geographic information (such as elevation and land use). Using statistical methods, we evaluate the suitability of this data as an impact proxy for wind gusts. While we find a strong correlation between user reports and model output, the data does not readily allow for a clear classification to predict user perceptions based on forecasts. We discuss potential ways to use this approach to improve communication with the public.

How to cite: Anger, F., Leschzyk, D., Lambert, A., Erhardt, B., and Feige, K.: Using Crowdsourced Data to Improve User Communication in Wind Gusts Warnings, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-355, https://doi.org/10.5194/ems2025-355, 2025.

In July 2021, dramatic flooding in western Germany and Belgium led to more than 200 deaths and massive destruction. Due to the increasing impact of climate change, such events are becoming more likely in the future. The German Weather Service (DWD) and the Rhineland-Palatinate Flood Forecasting Centre (HVZ) launched the joint co-design project in order to raise awareness in this regard and increase the ability to act. One of the project objectives is to analyze and improve risk and hazard communication with a focus on flooding at all possible levels. In particular, a clear understanding of how to deal with uncertainties and probabilities is a key element for quick and targeted decisions.

In summer 2024, we conducted a survey aimed at all stakeholders affected by flooding. The goal of this survey was to obtain detailed feedback on the understanding of uncertainties and to determine the interest and willingness to participate in workshops, courses, e-learnings and the (joint) development of serious games. The feedback on this topic was overwhelmingly positive. Numerous interested parties have declared their willingness to support these developments. In two large online meetings, we then brought the interested parties together and carried out an initial analysis of ideas for the development of a serious game focusing on dealing with meteorological and hydrological uncertainties. The target groups for this game should be civil protection, administrations, schools and the interested public. We are planning the entire development process in close dialogue with the user groups, allowing us to incorporate specific experiences from the various areas of work. In our presentation, we would like to present the current state of development of this game and discuss possible steps for further improving communication.

How to cite: Wolff, S., Bondy, J., Demuth, N., Fundel, V., Keller, J., Lambert, A., Leschzyk, D., and Voigt, M.: Improving flood communication at all levels with the help of a serious game, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-688, https://doi.org/10.5194/ems2025-688, 2025.