Vikash Sharma

The India Meteorological Department (IMD) on Tuesday announced that the most parts of the country will have good and well distributed rainfall activity during monsoon which is most likely to be normal with a quantitative forecast of 103 per cent of the Long Period Average (LPA).

As per IMD, the southwest monsoon has advanced over some more parts of central Arabian Sea, some parts of Karnataka, entire Kerala, some more parts of Tamil Nadu, entire southeast Bay of Bengal, some more parts of southwest Bay of Bengal,most parts of Eastcentral Bay of Bengal, some parts of Westcentral and Northeast Bay of Bengal.

Moreover, the conditions are favourable for further advance of Southwest monsoon into some more parts of central Arabian Sea,some more parts of Karnataka, some parts of Konkan & Goa, some more parts of Tamil Nadu, remaining parts of southwest Bay of Bengal, some more parts of westcentral Bay of Bengal, northeast Bay of Bengal, northeastern states and SubHimalayan West Bengal & Sikkim during the next 2-3 days.

“A normal monsoon rainfall is within the range of 96 to 104 per cent of the LPA. The IMD introduced the new LPA this April, based on rainfall data from 1971-2020 for the southwest monsoon season, replacing the data from 1961-2010. The LPA is 87 cm or 870 mm,” said IMD.

According to IMD DG Mrutyunjay Mohapatra, the monsoon season (June to September) over the country is likely to be 103 per cent of the LPA with a model error of plus/minus 4 per cent. The monsoon rain would be above normal in central and southern India (with more than 106 per cent of LPA) while it is most likely to be normal in the northeast (with 96-106 per cent of LPA of this region) and northwest India (with 92-108 per cent of LPA of this region).

The IMD also issued the forecast for what is called the monsoon core zone -- which consists of most of the rain-fed agricultural regions in Rajasthan, Gujarat, Madhya Pradesh, Maharashtra, Chhattisgarh and Odisha -- which, it said, would be above normal (more than 106 per cent).

"La Nina conditions are expected to continue throughout the monsoon period. Also, we are dependent on a dynamic system. All the statistical parameters, including all multimodal ensemble forecast -- surface air temperature, surface temperature over Pacific etc -- the consensus is for normal, but not 99 per cent but 103 per cent," Mohapatra explained about the revised quantitative forecast compared with what was announced in April.

La Nina conditions are likely to prevail over the equatorial Pacific Ocean and there is a possibility of development of negative Indian Ocean Dipole (IOD) conditions over the Indian Ocean during the monsoon season. IOD is the difference in the temperatures of west Indian Ocean and east Indian Ocean. La Nina is associated with cooling over the central and east Pacific Ocean.