North Tamil Nadu, including Chennai, was treated to some heavy to very rainfall accompanied by trademark thunder rolls and lightning through overnight and into Thursday morning, a day after India Meteorological Department (IMD) officially declared the arrival of this year’s North-East monsoon

Heavy to very heavy rainfall was reported from isolated places over Tamil Nadu, Puducherry and Karaikal and while it was heavy at isolated places over the Andaman & Nicobar Islands across and upstream in the Bay of Bengal from where the moisture-laden winds prevailed, the IMD said.

The IMD listed out the stations recording the heaviest rainfall (10 cm and above) during the 24 hours ending on Thursday morning as DGP Office (Chennai)- 18; Anna University (Chennai)-14; Tiruvallur and Numgambakkam-13 each; Rameswaram and Toothukudi-10 each.

Chennai swamped

Private forecaster Skymet Weather said that the rains in Chennai commenced late on Wednesday night and continued till morning to record 13.3 cm till 8.30 a.m in Nungambakkam. Airport observatory Meenambakkam measured 5.8 cm during this period. While Nungambakkam, with 31 cm rainfall in October so far, has nearly reached its monthly normal of 31.6 cm, Meenambakkam is just about halfway through with 15.4 cm.

Skymet said that there is a precedence for Chennai to have heavy rainfall spell in excess of 10 cm within days of onset of the North-East Monsoon albeit with few exceptions. The last six years have seen the onset getting delayed beyond October 25 with the exception of 2019 which witnessed early onset on October 16. In 2016 and 2018, Tamil Nadu recorded a large deficiency of 62 per cent and 44 per cent, respectively.

No major weather system

On Wednesday, there was no major rain-generating system (such as a low-pressure area/depression) in the Bay of Bengal to trigger the heavy to very rain but this seemed to have been more than offset by a resident cyclonic circulation off the North Tamil Nadu coast, which persisted through the day on Thursday as well.

The IMD said that scattered rainfall with moderate thunderstorm and lightning may lash Kerala, Tamil Nadu and Puducherry during the next five days with isolated heavy to very heavy rainfall over Tamil Nadu till Friday; isolated heavy rainfall on Friday, Saturday and Sunday; isolated heavy rainfall over Kerala on Sunday and Monday; and over South Interior Karnataka on Monday.

More rain forecast in TN

The Chennai Met Office under the IMD has forecast heavy to very heavy rain at isolated places over Chennai, Kancheepuram, Chengalpattu, Tiruvallur, Ranipet, Villupuram districts until Friday. Heavy rain is also likely over Tirunelveli, Tenkasi, Ramanathapuram and Thoothukudi districts.

Also read: Rain, thunderstorms as N-E monsoon arrives

An extended forecast for November 3-5 said that scattered to fairly widespread rainfall is likely over Tamil Nadu, Kerala and South Interior Karnataka; it would be isolated to scattered over Assam, the North-Eastern States; and the Andaman & Nicobar Islands. Isolated rainfall is forecast over Coastal Odisha and Lakshadweep Island.

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