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The report highlights the significant progress over various regions with respect to understanding of coastal hazards, numerical modeling techniques and the generation & dissemination of coastal hazard warnings and products. The developments over various regions in the globe during 2014-18 have been discussed in this report as presented during 10th Session of International Workshop on Tropical Cyclones (IWTC-X) at Bali, Indonesia. More specifically, various regions have started to confront the uncertainty that cannot be removed from TC analyses and forecasts and further communicate those hazards within the context of risk [probabilistic] based information. Progress also includes impact-based forecasts such as communicating coastal inundation information relative to total water level instead of storm surge, specifically (i.e., anomaly from astronomical tide and waves). Lastly, updates to model grid configuration, model resolution, and coupled dynamical systems continue to resolve the costal hazards more effectively. Those approaches have likely helped reduce loss of life relative to historical standards. However, regions agree that the generation and dissemination of coastal hazard information still need to be improved in view of growing population along the coast and thus increased exposure of life to coastal hazard. [ABSTRACT FROM AUTHOR]

This paper describes a series of hindcast simulations of 17 tropical cyclones over the northwest shelf region of Australia. Tropical cyclone track and vortex details were obtained from the Bureau of Meteorology "Best Track" database. Wind fields were simulated using a dynamic boundary layer model referred to as the Kepert-Wang model. Surface wind and pressure fields were blended with background fields from the ERA-Interim dataset. These blended wind fields were then used as forcing for the WAVEWATCH III wave model to generate wave fields. Several different configurations of wave model source terms were trialled. Wind and wave models were validated against available observations from the Bureau of Meteorology and our industry partner. The mean absolute error for peak significant wave height (Hs) for all configurations was mostly less than 0.90 m, compared to a mean observed peak Hs of 4.8 m, and the bias was less than around 0.41 m. It was found that while in general the ST6 wave model source term physics package with NL3 non-linear interactions performs well overall, there is no single configuration that performs best for all 17 tropical cyclones. [ABSTRACT FROM AUTHOR]

Tropical Cyclone (TC) wind and wave models are used to quantify meteorological and oceanographic conditions in the application of offshore engineering design criteria. In regions such as the North West Shelf of Australia, a statistically sound 'risk of failure' design assessment can require historical records far longer than are typically available, even with meteorological datasets of several decades length. To address this mismatch between design requirements and observational history, synthetic tropical cyclone wind and wave datasets can be developed to mimic long records with the objective of estimating extreme event average recurrence intervals of 10,000 years. Modelling large numbers of TC storms in practice requires a trade-off between time (computational efficiency) and accuracy (model skill). The development of the synthetic dataset in this study draws the balance by combining computationally efficient parametric models, and computationally intensive fully dynamic models, with different model grid resolutions. This paper outlines performance differences between the various model approaches and make recommendations for engineering. • Large number of high resolution wave model runs compared against parametric wave models under tropical cyclones (TCs). • Parametric wave models are limited to predict parameters other than significant wave height (e.g. peak wave period). • A coarse resolution dynamic wave model is strongly preferred for estimates of TC wave parameters. [ABSTRACT FROM AUTHOR]