A new low pressure area forming over the southwest Bay of Bengal, near the Sri Lanka coast, is set to trigger a fresh bout of intense northeast monsoon showers across Tamil Nadu from Sunday. According to the Regional Meteorological Centre (RMC), Chennai, rainfall activity — which had recently weakened — is likely to gain significant momentum over the next few days.
Delta to Be First Impacted; Coastal Belt Next
Weather models indicate that heavy rain will begin over the delta districts on Sunday before extending to the coastal stretch and nearby inland regions from Monday. The RMC has issued an orange alert for four regions, including Tiruvarur, Nagapattinam, and the Karaikal area, warning of very heavy rainfall ranging between 12 cm and 20 cm. Several districts, including Ramanathapuram and Sivagangai, may also experience heavy rain.
The low pressure formation can be traced back to an upper-air cyclonic circulation observed on Friday, which gradually intensified into a low pressure system by Saturday, meteorologists said. The development is expected to reinvigorate the northeast monsoon, which had recently slipped into a quieter phase.
Chennai to See Heavy Rainfall on Monday and Tuesday
While Chennai may see light to moderate rain on Sunday, the rainfall intensity is expected to increase from Monday. An orange alert has been issued for six districts, including Chengalpattu, Kancheepuram, and Tirunelveli, for Monday. Heavy to very heavy rain has been forecast for nine districts, including Chennai, Tiruvallur, Thanjavur, and Karaikal.
Intense spells could continue over northern districts such as Chennai and Villupuram, along with Puducherry, on Tuesday.
Rainfall Outlook Until November 21
Rainfall is likely to reduce and remain confined to The Nilgiris and the ghat regions of Coimbatore on November 19, followed by scattered showers across the State up to November 21.
Tamil Nadu has recorded nearly 26 cm of rainfall since the onset of the northeast monsoon on October 1, close to its seasonal average of 28 cm, and the renewed monsoon activity is expected to push the seasonal total above normal.
Another Weather System Brewing
The India Meteorological Department’s extended range forecast suggests another potential low pressure system may form over the Bay of Bengal around November 21, indicating promising rainfall prospects in the second half of the month.
Weather System Under Close Watch
B. Amudha, Head (Additional in-charge), RMC Chennai, said the evolving weather pattern is under continuous monitoring.
“Atmospheric parameters, including wind behaviour over the ocean, are being analysed to assess any further intensification. The movement of cloud bands will determine the regions that are likely to receive the heaviest spells,” she said.
