Uses of Frequently Updating Probabilistic Warn-on-Forecast Guidance

The Warn-on-Forecast (WoF) project at the National Oceanic and Atmospheric Administration (NOAA) National Severe Storms Laboratory in Norman, OK, USA, aims to provide forecasters with short-term, rapidly-updating, ensemble forecasts of thunderstorm hazards that produce usable and useful guidance between the Watch and Warning time scales. Ideally this guidance will enable the National Weather Service (NWS) to issue probabilistic warning information earlier and with greater spatial and temporal specificity for those who need it, when they need it. The system is envisioned to be a primary driver of a new NWS forecast paradigm known as FACETs, or Forecasting a Continuum of Environmental Threats.

Toward this end, a prototype WoF system called the NSSL Ensemble Warn-on-Forecast System for ensembles (NEWS-e), has been developed by WoF scientists and collaborators. NEWS-e is a frequently updated, on-demand convection-allowing ensemble analysis and prediction system, nested within an hourly convection-allowing ensemble forecast system, which currently is the High-Resolution Rapid Refresh Ensemble system developed by NOAA’s Earth System Research Laboratory, Global Systems Division. The NEWS-e system assimilates radar, satellite, and surface data every 15 minutes, and generates new probabilistic short-term forecasts at the top and bottom of each hour, at grid spacing O(~3 km).

To investigate the usability and usefulness of NEWS-e probabilistic guidance by forecasters, the system is being tested in real time in 2018 from May through most of July, using both naturalistic and experimental approaches. This study reports on the naturalistic approach, which explores the situational awareness gained from NEWS-e products and how this awareness is applied to decision making and the issuance of products that naturally evolve during actual NWS operations. Furthermore, this approach enables rapid prototyping in response to forecaster feedback on the visualization and performance of NEWS-e forecast guidance. Operational users included two Weather Forecast Offices, the FAA Command Center, and the MetWatch Desk at the Weather Prediction Center. This presentation will share examples on how NEWS-e has been used in real-time operations by forecasters and how the feedback they provided has been used to enhance its performance and usability.