The Influence of the Madden-Julian Oscillation in the distribution of convective intensities around Singapore from ground-based radar observations

Abstract

As more weather and climate extremes continue to occur and projected to intensify, this poses a threat to low-lying countries such as Singapore which are prone to flash flooding. Given that there are recurrent atmospheric phenomena that periodically occur and influence our weather such as the MJO, we seek to find out where these convective weather were occurring and their intensities around Singapore to provide observational reference for operational meteorologists, and to ana-lyse sounding parameters of convective thunderstorms across the MJO phases. Four years of radar data showed that the active MJO phase 8 was most favourable for severe (very severe and extreme) convection along the western and southern islands of Singapore. Widespread convec-tive thunderstorms around Singapore also tended to occur during the wetter MJO phases 1 – 4. The frequency of widespread and/or prolonged convection, during phases 6 – 8, also increases with increasing moisture in the atmosphere while this was invariant over phases 1 – 5. Lastly, hotspots of intense convection over Singapore tended to occur over the western and central north-south corridor of Singapore.