Twenty out of 32 districts in the State received much less rainfall during this year’s southwest monsoon (June-September) than the normal.

One district – Tuticorin – registered almost nil rainfall of 0.4 mm. It fell under the category of scanty rainfall (minus 60 per cent to minus 99 per cent). Nineteen others, including Chennai, Madurai and Tiruchi, fell under the classification of deficient (minus 20 per cent to minus 59 per cent).

Describing the rainfall received by the State as disappointing, Y.E. A. Raj, Deputy Director-General of Meteorology, says there were expectations that the State would experience more rainfall in the later part of the monsoon. But, it did not happen.

Coimbatore, Erode and Nagapattinam were among the districts that came under the category of normal rainfall (deviation: plus or minus 19 per cent).

Theni and Tiruvannamalai, representing the southern and northern regions, were the only two districts having positive values of departure. Both experienced normal rainfall.

Unlike 2011 when Chennai registered 75 per cent more rainfall during the southwest monsoon than the normal, the city recorded 347 mm, a deviation of minus 21 per cent. But, Madurai, which registered deficient rainfall of minus 43 per cent last year, posted a deviation of minus 44 per cent this year too. The rainfall received by the district in 2012 was 187.5 mm.

In the case of Tiruchi, this year’s rainfall was 204 mm, 60 mm less than that of the previous year. While the figure of departure was minus 31 per cent this time, it was minus 10 per cent last year.

Coimbatore, which had a surplus rainfall (33 per cent) last year just as Chennai, received 161.9 mm, a deviation of minus 15 per cent.

Northeast monsoon

As for the onset of the northeast monsoon, Dr. Raj points to the two previous years (2009 and 2010) when the advent of the monsoon was on October 29, though the normal date is October 20 with an allowance of seven days.

In 2011, the onset took place on October 25.

The monsoon is likely to be normal this time, going by different indications, he adds.

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