Final monsoon prediction later this month

BANGALORE, MAY 7. The India Meteorological Department (IMD) submitted its preliminary prediction of the coming monsoon to the Government in April and an updated estimate more recently. However, its Deputy Director-General for Weather Forecasting, Dr. V. Thapliyal, speaking at a symposium on atmospheric sciences, organised by the Indian National Science Academy here on Saturday, refused to divulge the prediction. The final prediction would be made public later this month, he said.

``Nobody should forget that a forecast is a forecast,'' warned Dr. Thapliyal. It was possible that the IMD was wrong and a provision should be made for any wrong forecast.

A monsoon would be considered normal if the total nationwide rainfall was within 10 per cent of the long-term average. Even in a season with a normal rainfall, four to six of the IMD's 35 sub- divisions could receive deficient rain.

The IMD's 16-parameter power regression model, which was being used operationally, had correctly forecast the monsoon for the last 12 years. Even in 1997, when the several El Nino effect was widely expected to result in a bad monsoon, the model correctly predicted a normal monsoon.

Dr. Thapliyal said alternate models which were being tried out so that regional forecasts would become possible, instead of prediction of only the total national rainfall as was the case now.

Dr. B. N. Goswami of the Indian Institute of Science drew attention to the vigorous fluctuations which could occur within a single monsoon season. The weak monsoon years were generally those with particularly vigorous fluctuations. Since these fluctuations were difficult to predict, the monsoon too was likely to continue to be a difficult system to predict.

Earlier, Prof. Roddam Narasimha presented an analysis of the variations in Indian rainfall over 120 years, which indicated that sunspot activity might be a factor.