General remarks
Despite the role that numerical weather prediction models play in giving general guidance on where favorable conditions are found for the onset of convection, more detailed information on the exact location is necessary. In the SPhR product, satellite images and model fields are combined into a single product which provides instability indices and moisture content. The satellite-derived instability fields can point at areas where the numerical model forecasts do not capture the actual developments accurately, e.g. the instability product may show different gradients and/or different intensities of instability. The satellite-derived products provide better spatial and temporal data than the NWP fields alone. Time sequences of the images are the best way to monitor changes in tropospheric moisture and stability.