Advances in Understanding and Forecasting Rapidly Changing Phenomena in Tropical Cyclones

ABSTRACT: This review of new understanding and forecasting of tropical cyclones (TCs) is based on presentations at the International Top-level Forum on Rapid Change Phenomena in Tropical Cyclones in Haikou, China. The major topics are the sudden changes in tracks, rapid changes in structure and intensity, rapid changes in rainfall, and advances in forecasting and forecaster requirements. Although improved track forecast guidance has been achieved with the Australian ACCESS-TC model and in track forecasts to 120h by the China Meteorological Administration, there is a continuing need for better understanding and improved track forecast guidance. Advances in understanding of processes related to rapid intensification (RI), secondary eyewall formation, mechanisms controlling inner-core structure and size changes, and structure and intensity changes at landfall have been achieved, but progress in prediction of rapid changes in structure and intensity has been slow. Taking into account complex interactions involved in TC-related rainfall, a prioritized list of physical processes that govern rainfall from landfalling TCs in China has been developed. While forecaster participants were generally encouraged by the progress being made, they expressed a strong desire for a transition of that new knowledge to timely and reliable forecast guidance products.