Evaluation, visualisation and communication of unusual weather phenomena in a compound framework

As technology evolves, it is important to keep the public informed about meteorological extremes in a reliable and effective way. In recent years, the communication of extremes is dominated by low effort, clickbait articles and the new possibilities of data visualisation are not yet fully explored and presented to the public. For these reasons, we present a methodology together with an interactive data visualisation platform, which can be used to evaluate past weather conditions and to visualise unusual periods in a simplified, easy-to-understand manner. The following innovative principles were used in our design: (1) the definitions of unusual phenomena must be based on relative thresholds and take into account seasonality; (2) the reference climatology must be spatially relevant; (3) the results should not be bound to specific calendar years or months; (4) unusual phenomena should be visualised simultaneously (to provide a compound framework). The expression “unusual” is used to describe anomalous values in contrast to the more commonly used “extreme”, because we aim to highlight periods with non-absolute weather extremes. With the use of these principles the comparison of unusual periods from different seasons also becomes possible and easy due to the definitions selected and the interactive nature of the visualisation. As input, daily meteorological data available at 70 stations across Hungary from 2002 to 2024 were used to create the methodology, where a total of 9 unusual weather phenomena are currently defined using temperature, precipitation and wind gust as basic variables. We developed a web-based application to visualise these unusual phenomena and added further functions and visualisations that can be useful for a wide range of users. In that regard, this application can also be seen as a science communication platform that gives its users a complex set of tools to explore and understand meteorological data.