An automated nowcasting system of mesoscale convective systems for the Mediterranean basin using Meteosat imagery. Part II: Verification statistics

Abstract

A nowcasting system of Mesoscale Convective Systems (MCSs) based on Meteosat Second Generation (MSG) imagery (described in part I) is applied on 109 MCSs identified over the Mediterranean region for a 16 day warm season period in order to statistically asses its performance. The dependence of the accuracy on forecast lead time as well as on the forecast cycle was also investigated. This first statistical verification of the system performance showed encouraging forecast accuracy although a gradual accuracy degradation is observed with forecast lead time. In general, forecasts can be acceptable up to a 105 min duration. Adequately accurate forecasts of the MCS parameters are obtained for a 45 min forecast range while a very good spatial agreement between forecasted and observed MCSs was found for a 60 min forecast range. A tendency for a slight improvement in the forecast skill is observed proceeding to the next forecast cycles. A presented case study demonstrated the value of the forecasting system in predicting both the movement and intensity of an MCS when applied in an appropriate situation. According to the verification results, the forecast scheme presented has proven to be a valuable tool in predicting the evolution of warm season isolated MCSs over the Mediterranean basin, even at the lower boundaries of the mesoscale.