Southwest monsoon’s excess rain fails to fill reservoirs in Tamil Nadu

Chennai: For a state that falls in the other side of Western Ghats, that effectively blocks moisture laden winds blowing in the southwest direction, Tamil Nadu counts the northeast monsoon as its primary source of rainfall and not the southwest monsoon.

But then, ask the Met department about their assessment of the rainfall activity in the state caused by SWM, during the monsoon months of June till September this year, chances are that you would receive a positive response.

So far this season, Tamil Nadu and Puducherry together have received 302.3 mm rainfall; only a slight shortfall of 2 per cent compared to the average 308.2 mm.

“We are within the normal variation limits, and this was expected even before the onset of the monsoon,” said S.B. Thampi, deputy director-general, Regional Meteorological Centre, Chennai. For the weathermen, any variation that falls within the +/- 19 per cent mark is deemed ‘normal’.

Meanwhile, a group of weather observers, associated with Kea Weather blog, has been keeping a keen eye on the rainfall.

Chennai city has so far received 519.3 mm, recording an excess of 85.5 mm above normal rainfall.

“This is the third year in a row that Chennai has received a good share of southwest monsoon rains, especially considering NE monsoon season is its prime source,” said Gopal Krishnan, a blogger at Kea Weather.

R. Pradeep John, part time blogger and fulltime employee with Tamil Nadu Urban Infrastructure Financial Services Limited, said the rainfall, though slow to pick up in Chennai, peaked in the month of August.

“On August 25, Chennai received 89 mm with nearly 75 mm being recorded in a span of just one hour. The last time, such an intense spell was witnessed occurred in June 6, 2011,” he said.
Among the regions that witnessed the highest rainfall was the Nilgiris at 982.7 mm, when it should have got only 755 mm, registering 30 per cent excess.

Significantly, Coimbatore district received 738.8 mm of rainfall, whereas its normal average is only 692 mm.

Two areas of Valparai and Chinna Kallar, falling within Kovai district have got plenty of rainfall, with the latter receiving more than 4,500 mm, becoming the wettest region in the state this season.

Tiruchy was rain-starved with only 140.7 mm rainfall, a drop of nearly 52 per cent than the normal rainfall.