Natural Hazards and Earth System Science www.nat-hazards-earth-syst-sci.net 1561-8633 1684-9981 7 2 2007 10.5194/nhess-7-327-2007 http://www.nat-hazards-earth-syst-sci.net/7/327/2007/ http://www.nat-hazards-earth-syst-sci.net/7/327/2007/nhess-7-327-2007.html http://www.nat-hazards-earth-syst-sci.net/7/327/2007/nhess-7-327-2007.pdf 327 342 2007-05-03 The skill of convective parameters and indices to predict isolated and severe thunderstorms M. Kunz michael.kunz@imk.uka.de Institut für Meteorologie und Klimaforschung, Universität Karlsruhe/Forschungszentrum Karlsruhe, Karlsruhe, Germany The preconvective environment on days with ordinary, widespread, and severe thunderstorms in Southwest Germany was investigated. Various thermodynamic and kinetic parameters calculated from radiosoundings at 12:00 UTC were verified against subsequent thunderstorm observations derived from SYNOP station data, radar data, and damage reports of a building insurance company. The skill of the convective parameters and indices to predict thunderstorms was evaluated by means of probability distribution functions, probabilities of thunderstorms according to an index threshold, and skill scores like the Heidke Skill Score (HSS) that are based on categorical verification. For the ordinary decision as to whether a thunderstorm day was expected or not, the best results were obtained with the original Lifted Index (80% prediction probability for LI≤−1.73; HSS=0.57 for LI≤1.76), the Showalter Index, and the modified K-Index. Considering days with isolated compared to widespread thunderstorms, the best performance is reached by the Deep Convective Index. 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