Chennai: A fourth low-pressure system is likely to form over the southeast Bay of Bengal around Nov 13 and intensify into a depression within 48 hours. However, whether it will bring heavy northeast monsoon rain to Chennai and neighbouring districts remains uncertain. A largely dry weather may prevail in the city and the suburbs for the next few days.Meteorologists said some weather models, based on conditions on Wednesday, indicate that the system could intensify into a cyclone and follow a track similar to severe cyclonic storm Murasu, which made landfall near Ongole in Andhra Pradesh. If it follows this track, Chennai may miss the system’s main rain-bearing region.V R Durai, director, Area Cyclone Warning Centre, RMC Chennai, said there were chances of the system intensifying into a cyclone, with sea-surface temperatures usually warmer during El Nino conditions. Also, during Nov, many cyclonic systems over the Bay of Bengal tend to move west-northwestwards towards the east coast, including Andhra Pradesh and Tamil Nadu. However, their tracks depend on the prevailing steering winds and atmospheric conditions.“The areas that may receive rainfall depends on where the system forms and the track it follows. The new low pressure is likely to form over southeast Bay of Bengal where cyclone Murasu originated. So it may take the same track, and that’s why we have not issued heavy rainfall forecast for Chennai for Nov 18-19. However, it is too early to say as the system is yet to form,” he said.Warm sea-surface temperatures can provide a developing weather system with heat and moisture, helping it gain strength. However, its eventual intensity and track will also depend on atmospheric conditions, including wind patterns around the system.For the next few days, Chennai and neighbouring districts are likely to experience largely dry weather. On Thursday, the city and suburbs may receive very light rain in some areas. Partly cloudy skies may keep temperatures between 24-25°C and 31-32°C.Meanwhile, nine delta and southern districts may receive moderate rain on Thursday. Maximum temperatures across Tamil Nadu are likely to remain near normal until Nov 15.Since Oct 1, Chennai has recorded 389mm of rain, 8% below normal. Chengalpet has received 223mm (38% deficit), Kancheepuram 225.7mm (25% deficit) and Tiruvallur, which houses Chennai’s drinking water reservoirs, 338.8mm (4% above normal).
