Progress in Building Formal Approaches for Regional Ensemble Prediction System Development

Future operational regional prediction systems, such as NOAA’s planned Rapid Refresh Forecast System, are being developed by collaborative teams assessing several components of high-resolution ensemble analysis and forecast system design. Largely, the design process for convection-permitting ensemble forecast systems remains ad hoc, but recent developments by an NCAR and NOAA team provides a pathway toward a more systematic forecast system design where a single-model, uniform-physics ensemble system is employed. This more formal approach includes: i) tools to trace sources of systematic model error to individual model components, such as specific physics packages; ii) diagnosis of scale dependent perturbation growth rates in ensemble forecasts; and iii) analysis system state and observation space diagnostics. Collectively, these can be leveraged to help guide forecasts system development activities when appropriately coupled with traditional forecast verification metrics. We will present highlights from recent experimental forecast system design tests in NOAA testbed demonstrations, progress in high-resolution ensemble analysis over the conterminous United States, model error detection using data assimilation with a time-averaged physics tendency diagnostic approach, and diagnostic tools for monitoring the rate and scale of perturbation error growth given different initial condition perturbation characteristics.