Servicio de Técnicas de Análisis y Predicción, STAP, Instituto Nacional de Meteorología (INM). Madrid - Spain
The specific tools and applications used at the INM (Spanish Meteorological Service) for the nowcasting and short-range forecasting of severe convective storms are presented. In the short range forecasting, outputs based on direct numerical model fields have been introduced. These include forecasting parameters as CAPE, CIN, vertical wind shear, storm relative helicity, precipitable water, WINDEX, etc. They are used in conjunction with standard fields and parameters. All of them provide guidance about the areas in which the possibility of significant convective activity development is higher, and also about the storm characteristics. For nowcasting purposes, an objective procedure to identify, analyse, diagnose, track and extrapolate radar data has been developed. In the first step, the procedure performs a bidimensional analysis (2D) using low level PPI or CAPPI reflectivity data to identify and separate convective regions from the rest of the radar echoes. In the second step a tridimensional analysis (3D) using volumetric reflectivity data identifies individual storm cells embedded in the 2D convective regions. The radar-based 2D and 3D information is a key point to support forecaster’s making decision processes related to nowcasting activities. Other products, such as combination of Meteosat Rapid Scan and national radar mosaic data (VIL, ECHOTOP), or radar-lightning combinations are been used in the operational environment.