LAUSR

The High-Resolution Ensemble Forecast system (HREF) Calibrated Thunder guidance is a suite of probabilistic forecast products designed to predict the likelihood of at least one cloud-to-ground (CG) lightning flash within 20 km (12 miles) of a point during a given 1-hour, 4-hour, and 24-hour time interval. This guidance takes advantage of a combination of storm-attribute and environmental fields produced by the convection-allowing HREF to objectively improve upon lightning forecasts generated by the non-convection-allowing Short-Range Ensemble Forecast system (SREF). This study provides an overview of how the HREF Calibrated Thunder guidance was developed and calibrated to be statistically reliable against observed CG lightning flashes recorded by the National Lightning Detection Network (NLDN). Performance metrics for the 1-hour, 4-hour, and 24-hour guidance are provided and compared to the respective SREF calibrated probabilistic lightning forecasts. The HREF Calibrated Thunder guidance has been implemented operationally within the National Weather Service and is now available to the public.