The India Met Department (IMD) has retained the ‘normal’ monsoon outlook (96- to 104 per cent of the long-period average, LPA) for this year and reaffirmed the onset date as June 6 along the Kerala coast.

This is the best news to emerge at a time when the country has been saddled with the second-worst rainfall record (a rainfall deficit of 25 per cent) during the just-concluded pre-monsoon season (March 1 to May 31).

Poor pre-monsoon rain

The IMD said that monsoon rainfall this year is likely to be 94 per cent of the LPA over North-West India; 100 per cent over Central India; 97 per cent over South Peninsula; and 91 per cent over North-East India — all with a model error of ± 8 per cent.

The monthly rainfall over the country as whole is likely to be 95 per cent of the LPA during July, the rainiest month, and 99 per cent of LPA during August, the second rainiest, with a model error of ± 9 per cent.

In the long-range forecast update issued on Friday, the IMD recalled that the monsoon had set in over the South Andaman Sea and some parts of the South Bay of Bengal on the normal date of May 18.

It further advanced into some more parts of South Andaman Sea on May 25 and into the southernmost parts of Maldives-Comorin area, parts of South-West and South-East Bay, the Andaman Sea, the Andaman Islands, and East-Central Bay by Thursday.

Onset date for Kerala

It is now expected to advance into extreme southern parts of the Arabian Sea and some more parts of Maldives and Comorin, South-West, and South-East and East-Central Bay during the next three days. Thereafter, the monsoon may strengthen and set in over Kerala around June 6, as predicted earlier.

The current weak El Nino conditions over the Equatorial Pacific are likely to continue during the monsoon season with some possibility of these conditions later turning to neutral conditions.

Another good augury pertained to the status of the Indian Ocean Dipole (IOD) conditions, which mimic the El Nino-La Nina phenomena in the country’s own backyard with implications for the monsoon.

Currently neutral IOD conditions prevail, but latest forecast from global models indicate that positive IOD conditions are likely to develop during the middle of the monsoon season and persist during the remainder of the season.

A positive IOD works to boost the concurrent Indian monsoon, often driving excess rain over Central India, in particular. A forecast of rainfall during the second half of the season (August and September) will be issued by July-end.

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