Probabilistic Hazard Information and Threats-in-Motion: Testing the Future of Warnings and Storm-Based Hazard Creation and Communication

Storm-based Probabilistic Hazard Information (PHI) is designed to provide a meaningful quantification of hazard likelihood with additional spatial and temporal precision relative to traditional weather warnings. PHI can help fill gaps between the watch and warnings as well as provide information for storms that may not meet full warning criteria. When provided by forecasters, this additional information potentially allows decision makers and the general public to gain a much more comprehensive understanding of weather threats than that available from traditional binary weather warning polygons. Additionally, PHI can be layered with Threats-In-Motion (TIM) which moves the deterministic warning polygons using the storm motion, providing equitable lead time for downstream users. Thus, the system of PHI and TIM together can allow end-users to personalize the level of information and lead time necessary for the individual. Experiments in the Hazardous Weather Testbed (HWT) at the NSSL have examined the production of PHI and TIM by National Weather Service forecasters using both archive events as well as live data.

Several novel concepts were evaluated in the recent Spring 2023 PHI Prototype HWT experiment, with a focus on addressing the feasibility of continuous forecaster generation of PHI and TIM simultaneously. A new, relatively unobtrusive notification system was introduced to alert forecasters to actions which may require their attention, such as rapidly increasing hazard probabilities suggested by automated guidance or hazard information which has not been recently updated. Significant updates to the stability of automated guidance were integrated into the experiment, and their impact on forecaster workload was measured. Additionally, possible communications with partners using NWS chat via Slack as well as public facing social media were investigated, with exciting new communications templates arising from the experiment. Feedback gathered during the experiment has provided inspiration and direction for further development of PHI and TIM-related research, as well as guidance for which concepts might successfully progress towards operations through Hazard Services, the next-generation forecast and warning software. This presentation will focus on both results from the most recent experiments as well as discuss the potential impacts for future communication of severe storms hazards and warnings.