Chennai placed under orange alert; Tamil Nadu gets heavy rain warning as low-pressure area forms over Bay of Bengal

A low-pressure area over the southwest Bay of Bengal, off the Sri Lanka coast, is likely to bring heavy rainfall to parts of Tamil Nadu from today, including the capital, Chennai. The Regional Meteorological Centre (RMC) in Chennai has issued an orange alert for four districts — including Tiruvarur, Nagapattinam and the Karaikal region — warning of very heavy rainfall between 12 and 20 cm on Sunday. Additionally, five districts, including Ramanathapuram and Sivagangai, are expected to receive heavy rain.The weatherman in it's forecast also predicted light to moderate rain accompanied by thunderstorms and lightning in Ariyalur, Cuddalore, Mayiladuthurai, Nagapattinam, Thanjavur, Tiruvarur and Viluppuram districts of Tamil Nadu, as well as Puducherry and Karaikal.Will Tamil Nadu see heavy rain tomorrow?The IMD has forecast light to moderate showers for November 17 in several parts of Tamil Nadu, with thunderstorms and lightning likely at one or two locations in Tamil Nadu, Puducherry and Karaikal. Heavy rainfall is also expected at isolated spots across a broad stretch of districts, including Tiruvallur, Chennai, Kancheepuram, Chengalpattu, Villupuram, Kallakurichi, Cuddalore, Mayiladuthurai, Nagapattinam, Tiruvarur and Thanjavur.What do the latest meteorological observations indicate?A “low-pressure area” over the southwest Bay of Bengal, off the Sri Lanka coast, remained nearly stationary as of 5:30 am on November 16. According to meteorological officials, the associated cyclonic upper-air circulation extends up to 5.8 km above mean sea level and tilts southwestward with height. The system is expected to move slowly in a west-northwest direction over the next 24 hours.Meanwhile, an “upper air cyclonic circulation” persists over south Bangladesh and its surrounding areas, extending up to 1.5 km above mean sea level.Additionally, a “cyclonic circulation” remains active over the southeast Arabian Sea and the adjoining South Kerala coast at around 0.9 km above mean sea levelThe upper-air cyclonic circulation observed on Friday, which evolved into a low-pressure area over the southwest Bay of Bengal off the Sri Lanka coast on Saturday, is expected to reinvigorate the Northeast monsoon, bringing an end to its recent lull.