We present, motivate, and evaluate Radar Maxima, a calibrated area-based probabilistic forecast product for heavy precipitation. It is designed to overcome inherent limitations of point-based forecasts, which often yield low probabilities for extreme events due to spatial displacement errors. The method aggregates radar-derived precipitation within 40 km neighbourhoods to statistically upscale forecasts from the ensemble system ICON-D2-EPS of DWD. Evaluation considers both objective verification metrics and feedback from operational weather forecasters based on case studies. Verification shows improved predictability, reliability and forecast sharpness. Evaluation of forecasters confirmed operational value in some cases.