The northeast monsoon is expected to set in over the State between October 23 and 25.
With the southwest monsoon retreating gradually over parts of Karnataka and Telangana, conditions are turning favourable for the onset of the northeast monsoon, which provides a major share of Tamil Nadu’s annual rainfall.
While Tamil Nadu awaits monsoon reversal, the Regional Meteorological Centre, Chennai, has predicted that wet weather would continue over parts of the State till October 19. A cyclonic circulation over south Tamil Nadu and its neighbouring areas would bring light to moderate rain. Ghat areas of Coimbatore, Theni and Dindigul districts may experience heavy rainfall in isolated places on Monday, and rain of heavy intensity may cover more districts, including Salem, Dharmapuri, Madurai and Erode, on Tuesday.
Officials of the Meteorological Department said the weather pattern was being monitored for the withdrawal of the southwest monsoon. It may withdraw further from various parts of the country, including Telangana and Maharashtra, in a couple of days. Both easterly and westerly winds prevailed in various regions due to the presence of the cyclonic circulation.
S. Balachandran, Additional Director-General of Meteorology, Chennai, said a wind shear zone was likely to develop over the region and sustain rainfall activity. The onset of the northeast monsoon would be declared only if certain criteria are met. They include the complete withdrawal of the southwest monsoon; the setting-in of easterlies over the Tamil Nadu coast; and fairly widespread rain over Tamil Nadu, south coastal Andhra Pradesh and nearby areas.
It may be recalled that the IMD had earlier predicted that the northeast monsoon rainfall between October and December would be normal, logging 88% to 112% of the long period average, which is 33.4 cm, over the south peninsular region. According to IMD data from 1977 to 2020, the earliest onset date was October 5, in 1984.
Chennai would continue to experience light or moderate rain and thunderstorms in some areas till Sunday. On Friday, too, places like Meenambakkam and West Tambaram received light rain.
