MeteoSwiss crowd-sourced hail reports

To bridge the gap between radar-based hail algorithms and automatic hail sensor measurements, the Mobiliar Lab for Natural Risks and the Federal Office of Meteorology and Climatology MeteoSwiss introduced in May 2015 a hail reporting function into the MeteoSwiss App. This crowd-sourcing project has been very successful, the number of reports exceeding 64’000 in summer 2019. We recently published an article on the crowdsourced hail reports in the Bulletin of American Meteorological Society BAMS (https://journals.ametsoc.org/doi/full/10.1175/BAMS-D-18-0090.1). In this article we describe the reports, how they were filtered, and show a comparison of the reported size with the two radar-based hail algorithms Probability of hail (POH) and Maximum expected severe hail size (MESHS).

Anyone in and close to Switzerland is very welcome to contribute and report the maximum size of hail on their smartphone whenever they observe it. Please, find more information on how to submit a crowd-sourced report in the MeteoSwiss blog that appeared on the 2nd of May 2019 (available in French, German and Italian). This blog is part of a 5-part blog series on hail in Switzerland.