Impact-Based Hail Forecasts for Switzerland in the scClim Project

Hail is a main contributor to weather-related damages to buildings, cars, and agriculture in Switzerland, demanding actionable information on hail risks and forecasts across sectors. The research project scClim addresses this demand by establishing a seamless model chain from observing, modelling and forecasting hail events to the quantification of hail impacts, including simulations to compare hail occurrence in current and future climate.

Within the project, we study several types of impact-based hail forecasts and warnings for Switzerland, addressing the interests of different stakeholder groups. We employ ensemble weather forecasts by the Swiss Meteorological Office combined with (a) impact-informed vulnerability thresholds to produce local hail warnings, and (b) information about exposed assets and their calibrated vulnerability to produce aggregated hail impact forecasts. While the impact-based forecasts would have to be thoroughly validated before operational use, the forecast products highlight how varying demands of different stakeholder groups shape the forecast product and the provided information.