Questions raised as Met errs on rain forecasts

With seasonal rainfall predictions having gone wrong twice this year, serious questions are being raised over the Met department and the credibility and accuracy of its long-range forecasts.

The Ministry of Earth Sciences conceded while answering a Parliament question on Wednesday that the accuracy of long-range forecasts in the past four years, excluding this year, has only been about 50 per cent. The short-range forecasts, of the order of a few days, have produced much better results, having an accuracy rate of between 70 and 95 per cent.

The long-range forecasts are made in April of the total amount of rainfall the country is likely to get in the four-month monsoon season from June to September.

What has happened this year has been particularly amusing. On April 26, the Indian Meteorological Department (IMD), in an annual exercise, predicted that the country as a whole would receive rainfall that would be 99 per cent of the long period average (the average of 1941 to 1990), or a normal monsoon season.

But two months later, when it announced the monthly and regional distribution of rainfall, the IMD made a downward revision and said rains were likely to be only 96 per cent of average. June and July, however, saw very less rainfall. By July, the shortfall in rains had reached 23 per cent, at which point the government seemed to panic. In an unusual step, the Prime Minister's Office issued a statement saying the total seasonal rainfall was likely to be only 92 per cent of the average and that the government was making all attempts to deal with a drought-like situation in some parts. A few days later, the IMD made a drastic cut in its estimates and said rainfall was not likely to be more than 85 per cent of average.

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