Thunderstorm nowcasting at IMGW

A storm detection model has been developed and implemented at the Institute of Meteorology and Water Management (IMGW), along with a forecast of the movement of storm cells with a leading time up to 60 minutes (TSP - Thunderstorm Prediction). The model is based on data from the 1-minute reports of the PERUN (lightning detection system): density of intercloud lightning, density of cloud-to-ground lightning, maximum lightning jump, number of lightning jumps, within 10 minutes. Another source of data are radar data from the POLRAD network and from neighboring countries: VIL (Vertically Integrated Liquid), EHT (Echo Top Height), CMAX (Column Maximum), CAPPI (Constant Altitude Plan Position Indicator), and the 0ºC isotherm altitude from the NWP COSMO model. In addition, Meteosat satellite data processed with NWC-SAF software: CTTH (cloud top temperature and height) and RDT-CW (rapidly developing thunderstorm – convection warning) were used. The heart of the system is a trained model based on the SVM (Support Vector Machines) method. Its calibration was carried out on observation data from synoptic stations located throughout Poland. This model determines the intensity class of the storm and the probability of its occurrence. The intensity forecast is based on the RDT-CW satellite product: the current and forecast storm intensity class and the forecast intensity class obtained with the SVM model. The probability predictions included RDT-CW, CTTH and parameters determined from the lightning dynamics analysis. The forecast of the movement of storm cells in the model is based on the displacement vectors obtained from the SCENE precipitation forecast model. A dedicated algorithm was developed for the graphical presentation of the TSP model results, which takes into account the uncertainty of the displacement vectors of the SCENE model, which affects the size of the area of potential storm occurrence in the assumed time horizon of 60 minutes. The results of the model have been used in services dedicated to aviation (Polish Air Traffic Control Agency) and are also presented to the public.