Hydrologic Post Processing Techniques (Invited Presentation)

Post-processing techniques for weather, water and climate information are beginning to be applied to the production and use of hydrologic ensemble forecasts. The NWS Hydrologic Ensemble Forecast Services (HEFS) that is being implemented nationwide uses post-processing techniques to generate precipitation and temperature forcing for hydrologic forecast models. HEFS includes a simple hydrologic post processing tool that can be used to post-process hydrologic model output. New York City is applying a hydrologic post-processor to use NWS HEFS ensemble forecasts for periods out to one year as input to create ensemble forecasts of the inflows to about 20 locations for an Operations Support Tool (OST) for the NYC water supply system. The assumptions and scientific foundations for the various post-processors will be reviewed and examples of the improvements they have made over using raw input forecast information will be presented.