Hail events in Germany, rare or frequent natural hazards?

Abstract. Hail in Germany is a natural hazard that is not in everyone's focus, even though it can cause great damage. In this study we focus on hail frequency, sizes and spatial distribution in Germany based on crowd sourcing and weather radar data. We derive hail sizes from radar reflectivity through the use of vertically integrated ice (VII) and maximum estimated size of hail (MESH). With that we create a hail climatology for Germany out of 6 years radar data. We found that hail can occur over whole Germany, but is much more probable in the south. The size of hail depends heavily on the storm, as we see hail tracks with large hail sizes. June is the month with the most and largest hail events. The mountainous areas are hit more frequently by hail than the lower parts. We analyzed crowd data in a short study to obtain how well people can estimate sizes especially hail sizes. In summary, the mean of a crowd is a quite good fit, but individual estimates can be very wrong. In comparison to radar data we found that MESH overestimates the hail size clearly, VII is in our case study a good fit.