The Indian Meteorological Department (IMD) has predicted heavy to very heavy rain in isolated places across Tamil Nadu, including Chennai, starting Thursday, November 10. A press release issued on Tuesday said that fairly widespread, widespread light or moderate rainfall with isolated heavy falls and thunderstorm and lightning are expected over Tamil Nadu, Puducherry and Karaikal during November 10-12.
On Thursday, heavy rain is likely to occur at isolated places over Ramanathapuram, Pudukkottai, Thanjavur, Tiruvarur, Nagapattinam, Mayiladuthurai, Cuddalore, Villupuram, Chengalpattu, Chennai, Kancheepuram, Tiruvallur, Kallakurichi, Ariyalur, Perambalur, Sivaganga, Puducherry and Karaikal. This will change to heavy to very heavy rains on November 11 and 12. Orange alert has been declared in several districts. The rainfall activity will continue on November 13 and is likely to decrease by the 14th. Heavy rain ranges from 64.5 to 115.5 mm while very heavy rain is from 115.6 to 204.4 mm.
The IMD said that a cyclonic circulation lies over the southwest Bay of Bengal and adjoining equatorial Indian Ocean and extends up to 4.5 km above mean sea level. The cyclonic circulation will lead to the formation of a low pressure area in the region, which will likely move northwestwards towards Tamilnadu-Puducherry coasts between November 9 and 11. The rainfall expected in Tamil Nadu, Puducherry and Karaikal during November 10-12 will result from this. Isolated very heavy rainfall is also likely over Tamil Nadu, Puducherry and Karaikal on November 11 and 12. Besides Tamil Nadu, Rayalaseema and south Andhra Pradesh too are expected to receive isolated heavy rainfall on these days.
In its press release, the IMD also said that squally winds with speed reaching 45-55 kmph and increasing to 65 kmph are “very likely to prevail over southwest Bay of Bengal and Sri Lanka coasts on November 10; over southwest Bay of Bengal, Gulf of Mannar, along and off Tamilnadu-south Andhra Pradesh on November 11 and 12.” It advised fisherfolk against venturing into the sea during this period.