Objective assessment of instability indices for operational hail forecasting in Greece

Summary This paper examines the performance of several atmospheric instability indices for operational hail forecasting in the Greek National Hail Suppression Program (GNHSP). These indices are part of the adopted forecasting procedure in the GNHSP, which also involves a synoptic index of convection and a synoptic scale typing scheme. The assessment of the indices is accomplished objectively through a multivariate statistical technique, namely factor analysis. The analysis resulted in grouping of the indices into three factors. The indices with high loading and scores are considered to best detect convection for hail forecasting in the GNHSP.With 4 Figures