An Evaluation of Stability Indices for Thunderstorm Prediction in Greater Cyprus

Abstract

The effectiveness of a number of forecasting indices for non-frontal thunderstorm activity has been investigated for the Greater Cyprus area. The indices include the humidity index (HI), the Pickup index (PI), the K-stability index, the Yonetani index in its original II and modified IIc, form, and the Showalter stability index (SSI) for the Mediterranean area. Combinations of some of these indices with information of the flow curvature are also considered. Two data sets, representative of coastal and inland locations are used to evaluate the accuracy of these indices. Verification statistics indicate that Yonetani's indices II and IIc, are more successful than the HI, PI, and K indices in the forecast of air mass thunderstorms. The addition of the flow curvature at 500 hPa improves the effectiveness of most indices and its inclusion should be seriously considered for the Eastern Mediterranean area.