Earlier, the system in the central part of South Bay of Bengal moved towards Southwest Bay of Bengal on Tuesday. The associated cyclonic circulation has extended up to 5.8 km above sea level and is expected to intensify as it moves west-northwestward over the Tamil Nadu coast during the next two days.
As a result, heavy to very heavy rain is predicted in Chennai, Thiruvallur, Chengalpattu, Cuddalore, Villupuram, and Puducherry and Kanchipuram districts on Wednesday.
Heavy rain activity is expected to continue over Chennai, Chengalpattu, Thiruvallur and Kanchipuram till Thursday, December 19. Light to moderate rain is likely over many parts of North Coastal Tamil Nadu and isolated areas over the rest of the state. Thunderstorms and lightning.