Conditions are becoming favourable, says India Meteorological Department

The stage is finally set for the onset of the monsoon over Kerala. The India Meteorological Department (IMD) on Thursday said conditions were favourable for the onset in the next three to four days.

A senior IMD official told TheHindu that the department was optimistic of an onset in the next three to four days as the weather prediction models showed that the winds over the Arabian Sea could be shifting direction in the next few days.

At present winds are flowing in the north-westerly direction, which is dry in nature. Models show that this could change and the winds could start flowing in the westerly or the south-westerly direction, which is necessary for the onset.

Mass of cloud

There are also indications that a mass of cloud that is hovering over the south central Arabian Sea could move westwards, paving the way for a fresh generation of clouds south of Kerala, which is another aspect that is essential for the onset.

Kerala is the first place the monsoon enters the Indian mainland. The normal date for the onset over the State is June 1. From the current indications, it appears that the event could take place even a day or two earlier. If that happens, it would also prove right the IMD's forecast issued earlier this month.

The IMD has been forecasting the onset date for the past six years and so far, the forecasts have, by and large, come true. Last year, it forecast the onset date as May 26, while the actual onset took place three days earlier, on May 23.

In 2008, the forecast was for May 29 and the actual date was May 31. In 2007, the respective dates were May 24 and May 28. In 2006 it was May 30 and May 26. The dates for 2005 were June 10 and June 7.

Last month, the IMD forecast a normal rainfall for this year with a precipitation of 98 per cent of the Long Period Average (LPA), subject to a model error of plus or minus 5 per cent for the entire monsoon season (from June to September) and for the country as a whole.

It, however, remains to be seen how far this prediction will come true. Last year, the department forecast a rainfall of 94 per cent plus or minus 5 per cent in April and then fine-tuned it to 93 per cent plus or minus 4 per cent. But, the country received a rainfall of 78 per cent of the LPA only for the season.

IMD experts emphasised that a normal onset need not necessarily mean that the rainfall would be normal for the season as a whole, as the country was too vast and the season was spread over a long period of four months. It takes two months to cover the entire country.

For instance, last year, the onset was on May 23, eight days before the normal date. But the season ended with a whopping deficiency of 22 per cent.

The IMD announced the forecast for the onset at the end of a media workshop organised by it. Experts, from several national institutions and organisations, including the Indian Space Research Organisation and the Indian Institute of Science, besides senior IMD officials and scientists noted that even international agencies could not predict last year's drought.