The water-starved city waits with fingers crossed for more rains. From what meteorologists have to say, this hope may not be in vain as there are signs that the Northeast monsoon will be favourable to the city.
There are still 20 days left for the Southwest monsoon to withdraw from the region and the rainfall over the city — with 381 mm — is slightly above the average 355 mm.
But, residents are waiting with bated breath for the Northeast monsoon — or the winter monsoon, as it known — which gives the city a major share of its annual rainfall.
The past three decades’ meteorological data reveal that the performance of the Northeast monsoon over the city has been satisfactory for the most time. Many a year, including last year, the monsoon set in on time, say meteorologists.
Normally, the monsoon sets in around October 20. A deviation of seven days, before or after October 20, is accepted as normal by the meteorological department.
Tracing the Northeast monsoon data since three decades ago, Y.E.A. Raj, former deputy director general of meteorology, noted that the city has experienced normal rainfall except for three or four years when the annual rainfall went below 100 cm against the average of 140 cm. The last decade ending 2010 has had a great monsoon, with good rainfall registered most of the years.
“We must remember that the average yearly rainfall was revised to 140 cm now due to recurrent good rainfall years. During the 1970s and the 1980s, the city’s average annual rains were measured at 122 cm,” he said.
With weather factors like El-nino and southern oscillation affecting Southwest monsoon over the country, it is expected to be favourable for Northeast monsoon this year. However, monsoon rain is controlled by many other factors and it is volatile unlike the Southwest monsoon, he adds.
While rainfall has been less than average for the last three years, Chennai has an advantage of Southwest monsoon filling the gap left by the winter monsoon, weather experts observe.
There is an urgent need to conserve water and create more water storage sources to tide over the crisis, they add.
