CHENNAI: Cyclonic Storm Ditwah -- over the southwest Bay of Bengal -- continued to lose strength on Sunday, even as it tracked almost directly north, running parallel to the Tamil Nadu–Puducherry coast.
The Regional Meteorological Centre (RMC), in its latest update, said the system slowed to 7 kmph over the past six hours and remained positioned over the same region.
It was centred about 90 km east-northeast of Karaikal, 120 km northeast of Vedaranniyam, 130 km southeast of Puducherry, 170 km north-northeast of Jaffna and 220 km south-southeast of Chennai.
A cyclone warning (red message) remains in place for north Tamil Nadu, Puducherry and adjoining south Andhra Pradesh coasts, with the IMD projecting the system to continue its northward run for the next 24 hours.
The weakened storm is expected to stay offshore, at a minimum distance of 70 km from the coast by noon and 30 km by evening.
However, the system’s structure has deteriorated significantly.
Weather blogger Pradeep John said Ditwah has “gone missing,” its core eroded by persistent dry air intrusion and strong vertical wind shear. What remains, he noted, is a depression-level circulation with little to no organised clouding.
Despite its weakening, Ditwah delivered very heavy rains across Tamil Nadu's coastal belts. Karaikal received the highest rainfall of 191 mm, followed by Nagapattinam with 113 mm and Cuddalore with 96 mm. Chennai's Nungambakkam and Meenambakkam weather stations received 28 mm of rainfall each.
IMD officials said the circulation, though stripped of convection, is still active and moving slowly towards the north Tamil Nadu coast. Numerical models suggest that cloud bands may redevelop later in the day as the remnant system inches closer to land.
This could bring renewed showers over the KTCC (Chennai–Tiruvallur–Kancheepuram–Chengalpattu) region, as well as Vellore and Ranipet, by evening or night.
While the cyclone threat has effectively diminished, forecasters caution that sudden bursts of rain remain likely due to the system’s proximity to the coast. Chennai, which has experienced subdued rainfall activity so far under the storm’s influence, may finally see some activity if cloud cover returns as expected later today.
Despite this weakening trend, the IMD retained the red and orange alerts issued already, cautioning that Ditwah would continue to bring heavy to very heavy rainfall to several coastal districts.
Rain activity is likely to persist till December 1. Sea conditions continue to be high to very rough and are likely to improve only from December 1. Fishermen have been advised to avoid venturing into the sea till then.