With northeasterly winds making conditions favourable, the India Meteorological Department has announced that the Northeast monsoon has set in over Tamil Nadu and Puducherry on Monday.

The Southwest monsoon too, has simultaneously withdrawn from the country.

Besides northeasterly winds setting in over lower tropospheric levels, many places in the State had also received rains on Sunday, paving the way for the arrival of the NE monsoon in the south peninsular region, said S. Balachandran, Deputy Director General of Meteorology, Chennai.

Normally, the NE monsoon sets in around October 20 over the State. During the past 24 hours ending 8.30 a.m. on Monday, Pulipatti in Madurai district received 11 cm of rainfall, which was the highest amount in the State for the day. Among many other weather stations, Viralimalai in Pudukottai district received the second-highest of 10 cm rainfall for the day.

“We expect an upper air circulation to form over southeast Bay of Bengal and the neighbourhood by Tuesday, and move westwards. A low pressure area is likely to develop over the central parts of south Bay of Bengal around October 28,” he said.

The weather system may influence widespread rainfall till October 29. Many places will record moderate rains and districts in southern parts and along the Western Ghats region are likely to receive heavy rains in one or two places till October 28.

On Tuesday, districts, including Ramanathapuram, Thoothukudi, Tirunelveli, Karur and Virudhunagar, have chances of isolated heavy rainfall accompanied by lightning and thunder.

Chennai may experience light to moderate rainfall in some areas till Wednesday and the day temperature will be around 34 degree Celsius.

October rain higher than average

This month, Tamil Nadu has so far received nearly 18.6 cm of rainfall, which is 33% more than the average of 14 cm for October.

The Meteorological Department has predicted that this year, monsoon rainfall is likely to be normal over the State, which is 44 cm between October and December.

Mr. Balachandran told Rashtra News that the Department is in the process of strengthening its weather network. Chennai and its fringes alone have a network of 22 automatic rain gauges. This would help in flood forecasting and collating data. The teams are also engaged in installing high windspeed recorders in Puducherry and Nagapattinam by Tuesday.

While the Chennai radar would be functional, another new radar at the National Institute of Ocean Technology, Pallikaranai would also be made available soon for monsoon observation, he added.