New convective guidance at the Australian Bureau of Meteorology

Operational guidance for thunderstorms and severe convective hazards at the Australian Bureau of Meteorology has undergone a major uplift in recent years, with the introduction of new NWP models, post-processing systems, and convection diagnostics. The latest guidance is based on the third generation of the Australian Community Climate and Earth-System Simulator (ACCESS) suite, which includes global and convection-allowing models run in both deterministic and ensemble configurations. In this presentation, we will introduce the ACCESS suite and discuss three sources of convective guidance based on its outputs. The first is the new ConvParams post-processing suite, which ingests model-level data from the ACCESS Global and Global Ensemble models and computes a wide array of convective parameters for use in ingredients-based forecasting of thunderstorms and associated hazards. The second is the Bureau’s lightning prediction system, Calibrated Thunder, which combines ACCESS Global Ensemble forecasts and recent lightning observations to produce calibrated probabilistic forecasts of lightning within a 10-km radius across Australia and surrounding coastal waters. The third comprises storm attributes from the convection-allowing ACCESS City and ACCESS City Ensemble models, including simulated reflectivity, updraft helicity, and parameterised lightning flash rates. For the ensemble, these diagnostics are post-processed to obtain the ensemble maximum and neighbourhood-maximum ensemble probabilities (NMEPs), and interrogated using a variety of novel visualisation strategies. Our presentation will provide an overview of each of these guidance streams, describe how they are used in operations, and assess their strengths and limitations. We will also highlight promising avenues for future guidance developments at the Bureau of Meteorology.