Short-term risk forecasts of severe weather

Abstract Methodologies for risk forecasts of severe weather hardly exist on the scale of nowcasting (0–3 hours). In this contribution we discuss short-term risk forecasts of hail by using COTREC/RainCast: a procedure to extrapolate radar images into the near future. An error density function is defined using the error of location of the extrapolated radar patterns. The radar forecast is folded (“smeared”) with the density function, leading to a probability distribution of radar intensities. An algorithm to convert the radar data into signatures of hail provides the desired probability (or risk) of hail at any position within the considered window in space and time. This methodology is considered to be useful for risk forecasts of floods, heavy wind and snowfall or freezing rain as well. We will discuss the design of appropriate forecast models.