Short range forecast of convective rain using satellite data

Abstract

The potential use of Meteosat Second Generation (MSG) clear air products in forecasts of convective rain over Germany in summer is examined. The three quantities Lifted Index (LI), Layer Precipitable Water (LPW ML ) of the Middle Layer and the trend of the Lifted Index (dLI/dt) are combined in a heuristic approach to gain a probabilistic forecast of convective rain with a lead time of three to six hours. Data from 33 days with a typical convective weather situation in summer 2005 and summer 2006 were used to derive the data pool necessary for the probabilistic forecast. The input parameter LI, LPW ML and dLI/dt were divided into 5, 4 and 5 classes, respectively. This leads to 100 possible combinations of the input parameters. For each set of input parameter, the information about rain three to six hours later is assigned. DWD radar data are used to detect the rain pattern three to six hours later. For typical summer convective days in Germany, a valuable probability forecast of convective rain is calculated for cloud-free areas.