CHENNAI: The unprecedented rain in the State has become a subject of intense discussion among meteorologists who, while acknowledging that incidence of extreme weather events is on the rise, say it is premature to establish any one-to-one correspondence.

N. Jayanthi, Deputy Director-General of Meteorology (weather forecasting), Pune, says statistical data point to increasing tendency of high impact incidents such as unusually high rainfall as recorded in Mumbai, Bangalore and Chennai this year.

"Global warming may be a reason. But this has to be studied," says S. Sridharan, Deputy Director-General of Meteorology, Regional Meteorological Centre, Chennai.

A senior meteorologist, who wishes to remain anonymous, says even assuming that global warming is the cause, there has to be a pattern in heavy rainfall over a considerably long period. Tamil Nadu did not record heavy rainfall last year or the year before. One year's rainfall cannot be taken to arrive at a conclusion.

Analysing the behaviour of the northeast monsoon this time, Dr. Jayanthi, who was earlier director of the Meenambakkam observatory, says the widespread heavy rainfall over Tamil Nadu was mainly because the cyclonic systems did not become intense and concentrated. The cyclonic activity was confined much to the south of the normal active zone. Whatever developed over the Bay of Bengal did not become severe or very severe cyclones. As there was a low-pressure area or depression over the Bay, the rainfall was widespread. One positive feature was the absence of strong gale force winds and storm surges.

Mr. Sridharan does not consider unusual the scenario of cyclonic systems crossing the coast of north Tamil Nadu in late November or December. The chances of the systems going to Andhra Pradesh or Orissa are more in October. But in November and December, the cyclonic systems invariably hit the coast of Tamil Nadu, be it in the north or in the south.

Depression

According to the weather office, at 8-30 a.m. on Tuesday a depression over southeast Bay of Bengal lay centred at about 1,100 km east southeast of the city. It is likely to intensify further and move in a west northwesterly direction. Its impact may be felt in two days.

Printer friendly page  
Send this article to Friends by E-Mail