Real-Time Convection Permitting Forecasts for the Maritime Continent Using the Unified Model.

Since the end of 2016 the Met Office has been running real-time convection permitting (CP) Unified Model (UM) model forecasts for the Maritime Continent as part of a UK government Newton fund project. These include a 4.4 km deterministic model covering the whole Maritime continent region, a corresponding 18-member 4.4 km ensemble, and several nested 1.5 km models to provide more detailed forecasts for in-region partner countries.

In this presentation some of the main results coming out of the project thus far will be illustrated using examples from high impact weather events. Focussing first on the deterministic forecasts, the benefits of the 4.4 km CP forecasts over the 10 km (parametrized convection) global model forecasts will be illustrated. The most striking improvements are in the rainfall distribution, which is qualitatively improved both in terms of spatial and temporal behaviour. The extra detail and associated benefits of 1.5 km forecasts over 4.4 km forecasts will also be considered. The value of the probabilistic forecasts provided by the 4.4 km ensemble compared to the equivalent deterministic forecast will also be assessed. Typically the probabilistic forecasts are of greatest value in high impact weather situations and examples reflecting this will be presented.

One of the novel aspects of this project is that it is developing tools to improve the translation of forecast model output into advice that can help mitigate against high impact weather. Some examples of these new visualisation tools will be presented.

Finally, future plans to further develop and improve the real-time forecasting system will be presented.