In its preliminary monsoon forecast, the India Meteorological Department (IMD), the official weather forecasting agency, has said that the nationwide rainfall this monsoon season will be 5 per cent less than the average of 89 cm.

Though this is less than last year, which received 100 per cent of the long-term average rainfall against a forecast of 93 per cent, it is well within the normal range and should not be cause for concern.

“The error margin is five per cent which means it can be 100 per cent in the best case scenario,” said P S Goel, Secretary in the Ministry of Earth Sciences.

The forecast has been made as per a new model introduced this year with an inbuilt error of +/-5 per cent. This is the second time since 2002 that the IMD has had to discard its forecast model and opt for a new one. The 16-parameter Gowarikar model, in operation for over 14 years, was discarded in 2003 after the model failed to forecast the 2002 drought. The 8 and 10 parameter models, which replaced the Gowarikar model and were in operation for the last four years, have now been replaced by two forecast models — 5-parameter model for making an initial forecast in April and 6-parameter model for making the final forecast in June.

The weathermen declined to cate categorise the forecast — whether or not it can be called a normal monsoon — because the new model does not have any such category.

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