Chennai and neighbouring districts may see moderate rain, thunderstorms and gusty winds over the next few days, with the India Meteorological Department forecasting heavy rain in Tiruvallur on Saturday.
The IMD has forecast moderate rain at one or two places in Chennai, Tiruvallur, Chengelpet, Kancheepuram and other north Tamil Nadu and interior districts on Thursday and Friday. Rain activity is expected to strengthen after several days of short, isolated spells.
V R Durai, director of the Area Cyclone Warning Centre, said an upper-air circulation over south coastal Andhra Pradesh and adjoining Rayalaseema, together with a trough extending from north interior Karnataka to the Gulf of Mannar, could bring rain to Chennai, nearby districts and other parts of Tamil Nadu.
An upper-air circulation is an area where winds rotate around a region of relatively low pressure several kilometres above the ground. It can draw moisture into the atmosphere and encourage air to rise. A trough is an elongated zone of relatively low pressure that can also support rising air and cloud formation.
“It may not be widespread rain in the city, but moderate spells are possible in some areas till Sept 20,” Durai said.
The IMD said thunderstorms and lightning may occur in some areas on Sept 17 and 18, accompanied by gusty winds reaching 40-50 kmph. In Chennai, light to moderate rain is expected during the evening and night on Thursday, with partly cloudy skies. Daytime temperatures may remain between 35°C and 36°C, while nighttime temperatures are expected to stay around 27°C to 28°C.
The rainfall pattern is uneven across the region. Since June 1, Chennai has recorded 361.4mm of rain, about 2% below normal. Nungambakkam has received 392.7mm, around 10.7mm above normal, while Meenambakkam has recorded 422.4mm, approximately 6.1mm below normal.
The wider districts have recorded larger deficits. Tiruvallur has received 86.3mm, 22% below normal; Kancheepuram has recorded 264.6mm, 33% below normal; and Chengalpet has received 154.5mm, 54% below normal.
The forecast covers a period when short-duration rain can affect road conditions, visibility and local movement even if rainfall is not widespread across the city. The IMD’s next forecast updates will indicate whether the expected spells intensify or remain confined to isolated areas.
