The India Meteorological Department (IMD) has issued a ‘nowcast rain alert’ for five Tamil Nadu districts, including Chennai, Poonamallee, and Tambaram, predicting heavy rainfall over the next 2-3 days. An orange alert is in effect for Chennai, Tiruvallur, Kanchipuram, and Chengalpattu today. Isolated heavy rains are also expected in Tamil Nadu, Puducherry, and Karaikal on October 18, 20, and 21.