Provided a correlation exists between the actual hazardous phenomena of interest and large-scale environmental predictors well resolved by the ensemble models, the application of climate data can be used to post-process and downscale ensemble probabilistic guidance thereby removing systematic biases and improving statistical reliability. The SPC applies a frequency correction technique to calibrate and downscale ensemble probabilistic guidance to aid in operational forecasting and real-time decision making. This post-processing relies on climatic databases of hazardous phenomena such as cloud-to-ground lightning, severe convective weather reports, and even winter road surface information.
This paper discusses the importance of maintaining real-time databases of hazardous weather phenomena across a wide range of operational programs to improve real-time ensemble guidance. The application of the SPC frequency correction technique to hazardous forecast problems is demonstrated and some verification results provided. Non-steady climatic data sets introduce additional challenges; trends in the long-term data are difficult to overcome when certain calibration techniques such as reforecasting are utilized. These challenges are also discussed.