Recent trends and variabilities of convective parameters relevant for hail events in Germany and Europe

Most of the CPs that rely on moisture at the near-surface layers exhibit a significant positive trend towards a higher convective potential. This finding applies to the 90% (10%) percentiles of the annual distribution and to the number of days that exceed (or fall below) a specific threshold, which is suitable for hailstorm prediction. Negative and, at most stations, insignificant trends of CPs that rely on moisture at higher levels or if the initial parameters of the lifting curve were mixed over the lowest layers can be attributed to inconsistency in the time series of the dew point. This in homogeneity is caused by changes in the instrumentation around the year 1990. The investigations show considerable spatial differences in the convective potential both in the mean and the trends, with a distinct north-to-south gradient and a less marked west-to-east gradient over Europe and Germany. The spatial distribution of the trends, however, is fairly consistent among the CPs that are based on the same principles.