Convective-scale Warn-on-Forecast

Warn-on-Forecast is a ten-year National Oceanic and Atmospheric Administration project to extend severe weather warning lead times by incorporating forecasts from a convection-permitting ensemble modeling system into the warning decision process. Current warn-on-forecast case study results with convection-permitting ensembles that assimilate WSR-88D radar reflectivity and radial velocity observations show that accurate analyses and reasonable 0-1 h probabilistic forecasts of strong near surface vertical vorticity – used as a proxy for tornadoes - are possible for isolated supercell storms. However, while accurate convective-scale analyses are produced for mesoscale convective systems, obtaining reasonable probabilistic convective system forecasts is more challenging.

The motivation for Warn-on-Forecast will be outlined. Results from several warn-on-forecast data assimilation and prediction experiments and from real-time testing of a convective-scale three-dimensional variational analysis system within the NOAA Hazardous Weather Testbed will be shown to highlight where progress has been made and where challenges remain. While other presentations at the conference will provide detailed information on various case studies and project activities, this overview will outline the common themes arising from these experiments and provide a vision for the future.