The India Meteorological Department (IMD) confirmed on Thursday that the deep depression over the southwest Bay of Bengal has strengthened into a cyclonic storm.
The system is expected to bring widespread rainfall to several southern states over the next few days.
In its latest update, issued at 9:10 a.m. on Thursday, the IMD said, “The Deep Depression over southwest Bay of Bengal and adjoining Sri Lanka coast moved north-northwestwards with a speed of 17 kmph during past 6 hours, and lay centered at 0830 hrs IST of today, the 27th November 2025 over the same region near latitude 6.7°N and longitude 82.1°E, about 120 km south-southeast of Batticaloa (Sri Lanka), 130 km east-northeast of Hambantota (Sri Lanka), and, 640 km south-southeast of Puducherry and 730 km south-southeast of Chennai (India).”
The IMD added, “It is very likely to continue to move nearly north-northwestwards across the southwest Bay of Bengal & adjoining Sri Lanka and intensify further into a cyclonic storm during the next 03 hours. Thereafter, it is very likely to continue to move north-northwestwards across the southwest Bay of Bengal & adjoining Sri Lanka coast towards North #Tamil_Nadu, #Puducherry and adjoining south #Andhra_Pradesh coasts during subsequent 48 hours.”
Once named, the system will be called Cyclone Ditwah. The name was proposed by Yemen. “Ditwah” or “Detwah” refers to a well-known lagoon on Yemen’s Socotra island.
The IMD said Tamil Nadu will receive heavy to very heavy rainfall until December 1, with isolated extremely heavy rain on November 29 and 30. This has led to an orange alert for Chennai and other coastal districts on November 29–30.
Several areas across southern India, including Kerala, coastal Andhra Pradesh, Rayalaseema, Yanam and Mahe, are also likely to receive heavy to very heavy rain until November 30.
The weather agency issued a yellow alert for coastal Tamil Nadu on November 28. Heavy rainfall is likely in Ramanathapuram, Sivaganga, Pudukkottai, Ariyalur, Cuddalore and Mayiladuthurai. An orange alert was issued for Thanjavur, Tiruvarur, Nagapattinam and Karaikal for the same period.
On November 29, many Tamil Nadu districts, including Tiruvarur, Nagapattinam, Mayiladuthurai, Cuddalore, Villuppuram, Chengalpattu, Tiruvallur, Chennai, Kancheepuram, Ranipet, Tiruvannamalai, Kallakurichi, Ariyalur, Perambalur and Thanjavur, are likely to receive heavy to very heavy rain. Puducherry and Karaikal will experience similar weather. These regions are under an orange alert.
For November 30, an orange alert has been issued again for Chennai and surrounding coastal districts. The IMD warned that “isolated Heavy to very heavy rain with extremely heavy at one or two places is likely to occur over Tiruvallur district. Heavy to very heavy rain is likely to occur at isolated places over Ranipet, Chennai, Chengalpattu and Kancheepuram districts.” Heavy rain is also expected in Tiruvannamalai, Vellore and Villuppuram, along with Puducherry.
The approaching storm has prompted alerts across Tamil Nadu, Andhra Pradesh, and other southern states. Chennai and nearby districts are expected to witness intense rainfall through November 30. Coastal Andhra Pradesh, Yanam, and the Andaman and Nicobar Islands will also receive heavy rain during this period.
According to the Met Centre Amaravati, the coastal districts of Andhra Pradesh and Rayalaseema will see heavy rainfall on November 28. Very heavy to extremely heavy rainfall is expected on November 29 and 30 as the system moves closer to the coast.