According to the Regional Meteorological Centre (RMC), Chennai, a weak trough in the lower levels of the atmosphere persists over the Tamil Nadu coastal region. The weather system is expected to trigger moderate rain with thunderstorms in the Western Ghats districts from July 29 onwards. The weather office said isolated places in the Nilgiris district are likely to receive heavy rainfall on July 30. It further forecast heavy rain at one or two places in Coimbatore, Nilgiris and Theni districts on July 31 and again on August 1. At the same time, much of the rest of Tamil Nadu continues to experience above-normal temperatures.