Numerical Simulations and Analysis of June 16, 2010 Heavy Rainfall Event over Singapore Using the WRFV3 Model

The Numerical Simulations of the June 16, 2010, Heavy Rainfall Event over Singapore are highlighted by an unprecedented precipitation which produced widespread, massive flooding in and around Singapore. The objective of this study is to check the ability of Weather Research Forecasting version 3 (WRFV3) model to predict the heavy rain event over Singapore. Results suggest that simulated precipitation amounts are sensitive to the choice of cumulus parameterization. Various model configurations with initial and boundary conditions from the NCEP Final Global Analysis (FNL), convective and microphysical process parameterizations, and nested-grid interactions have been tested with 48-hour (June 15–17, 2010) integrations of the WRFV3. The spatial distributions of large-scale circulation and dynamical and thermodynamical fields have been simulated reasonably well in the model. The model produced maximum precipitation of ~5 cm over Changi airport which is very near to observation (6.4？cm recorded at Changi airport). The model simulated dynamic and thermodynamic features at 00UTC of June 16, 2010, lead to understand the structure of the mesoscale convective system (MCS) that caused the extreme precipitation over Singapore. It is observed that Singapore heavy rain was the result of an interaction of synoptic-scale weather systems with the mesoscale features. 1. Introduction On 16th June 2010, a heavy rainfall event occurred in Singapore producing devastating flash flood and tremendous amount of property damage (Singapore’s national water agency (PUB) report, Annual Weather Review, 2010, NEA, Singapore). Heavy rainfall is usually resulted from individual mesoscale storms or mesoscale convective systems (MCSs) embedded in synoptic-scale disturbances [1]. High-resolution observations and numerical modeling technique are needed to better predict heavy rainfall events and understand the evolution and development mechanisms of mesoscale convection and storms responsible for heavy rainfall. In this study, a high-resolution version of the WRFV3 (Weather Research and Forecasting Version 3) model is used to investigate the predictability of heavy rainfall over Singapore and try to exploit the mesoscale convective systems which are highly interacting with synoptic-scale environment. WRFV3 has been used successfully for predicting heavy rainfall which occurred in many different countries and for understanding the associated convective systems [2–7]. The objective of the present study is to identify the best possible microphysics, cumulus, and PBL scheme for simulation of