How Well Can the Met Office Unified Model Predict Tropical Cyclones?

Convection-permitting (CP) NWP models are a key tool for forecasting tropical cyclone (TC) intensities, intensity changes and precipitation. This paper examines how well a CP, regional configuration of the Met Office Unified Model (UM) can predict TCs, compared to the Met Office global model used to drive it. It is shown that the CP model provides much improved predictions for the intensities of strong storms (category 3 and above) and can successfully capture some rapid intensification (RI) events, whereas the global model cannot predict RI at all. The spatial location of rainfall within intense TCs is also more skilfully predicted by the regional model, and the statistical distribution of rain-rates is closer to that observed. Although the regional model adds value over the global model, notable biases are also identified, highlighting areas for future work to develop and improve the model.