In an unprecedented manner heavy rain lashed out in Chennai during the month of November 2021 

In the past Historical rainfall data reveals :

1918 November received  1088 mm

2015 November received 1049 mm

2021 November received 1025 mm ( as at  17:30 HRS 28/11/2021) 

During the last 24 hours, Nungambakkam received the highest rainfall of 36.4 mm, followed by Anna University 33 mm, Meenambakkam 25.4 mm, Taramani 19 mm and West Tambaram 9 mm. Whereas in other districts, Ramanathapuram, Chengalpattu recorded 11 cm each, Tiruvarur 10 cm, Karaikala, Mayildathurai and Cuddalore 8 cm each.

“Due to atmospheric overlay circulation over Kanyakumari coast, and adjoining Sri Lanka coast, several districts of Tamil Nadu – Thoothukudi, Ramanathapuram, Mayiladuthurai, Nagapattinam, Cuddalore and to witness heavy to very heavy rains along with thunderstorm for 24 hours, and heavy rains are likely to occur over Chennai, Kanyakumari, Tirunelveli, Madurai, Villupuram, Thanjavur, Tiruvarur Pudukkottai, Ariyalur, Chengalpattu, Tiruvallur, and Kancheepuram,” said N Puviarasan, Director, Area Cyclone Warning Centre, Regional Meteorological Center (RMC), Chennai.

On November 29 and 30, Kanyakumari and Tirunelveli witness heavy to very heavy rains, meanwhile heavy rains are expected to receive over Thoothukudi and Ramanathapuram. 

And thunderstorm with moderate rain is likely to occur at most places over the rest Coastal and Southern districts of Tamil Nadu.

“A new low-pressure area which was expected to form over the south Andaman Sea on Monday has been delayed and it is likely to form on November 30. 

And it may further strengthen and move towards the west-northwest. However, there is no prediction of an impact for Tamil Nadu due to this low-pressure formation,” said Puviarasu.

RMC cautioned fishermen not to venture into the sea for the next 48 hours as strong winds are expected to blow at a speed of 40 kmph to 50 kmph over Kanyakumari coast, southeastern Arabian Sea and Kerala coast.

Speaking to reporters in Delhi, IMD Director General Mrutyunjay Mohapatra said a low pressure area is likely to form over South Andaman Sea and the Bay of Bengal around November 30.

“It is likely to become more marked and move west-northwestwards during subsequent 48 hours. This could become a cyclonic system in the first week of December, affecting Andhra Pradesh and Odisha,” he said.

Under its influence, squally weather with maximum sustained wind speed reaching up to 60 kmph is likely to prevail over South Andaman Sea and adjoining southeast Bay of Bengal from November 30 and December 2, he said.