Probabilistic Hazard Information for Severe Convective Storms in FACETS—Progress and Plans

The Forecasting a Continuum of Environmental Threats (FACETs) paradigm is a proposed modernization of the National Weather Service’s (NWS) deterministic severe weather warning system towards a probabilistic methodology for severe weather warnings and outlooks. The development of Probabilistic Hazard Information (PHI) as a data stream in the analysis and communication of these threats is a key component in FACETs. PHI provides short-term probabilistic guidance for threats such as tornadoes, large hail, damaging wind and lightning.

Some of the physical and social science concepts and methodologies that serve as foundational underpinnings for FACETs include: 1) using a large, reanalysis dataset of convective storms using WSR-88D data for model verification (MYRORSS), 2) providing storm-based probabilistic trends and historical distributions of convective storm features for use in the probabilistic hazard information (PHI) tool, 3) understanding how different forecasters interpret, process, and utilize probability grids within the warning decision process, and 4) understanding how probabilistic hazard information can be communicated to end-users for decision-support.

The presentation gives an overview of ongoing work to define spatiotemporal nowcasts with improved information of specific thunderstorm hazards to update the PHI nowcast model and bring it closer to operational readiness as well as plans for testing in a 2020 Hazardous Weather Testbed experiment.