The southwest monsoon this year was 8% over its long-term average, however, rainfall is likely to continue in October and November with ‘above normal’ monsoon rainfall expected, the India Meteorological Department (IMD) said on Tuesday.
About 35% of the country received ‘excess rainfall’ and slightly over half, or 54%, receiving ‘normal’ rainfall. Monthly rainfall over the country as a whole was 89% of the average in June, 9% more than normal of July, 15% above the normal of August, and 12% over the normal of September.
The actual monsoon performance — of above average rainfall — is in line with what the agency has forecast since July.
During the monsoon months, the agency had said that a key factor for bountiful rainfall would be La Nina, or a minimum half a degree cooling of the Central Equatorial Pacific, that was to have set in by September. This, however, has not happened with most of the international climate models, including India’s going wrong on this factor. “We don’t know specifically why La Nina hasn’t set in but most models, on average, give a 71% chance for La Nina to set in during October, November and December,” said M. Mohapatra, Director General, IMD.
The main reason for good rainfall this season was the formation of several low pressure systems — or moisture-laden winds from the Arabian Sea or Bay of Bengal — with 14 of them having formed from June to September.
According to the agency’s forecast, the rainfall over south peninsular India consisting of five meteorological subdivisions (Tamil Nadu, coastal Andhra Pradesh, Rayalaseema, Kerala and south interior Karnataka) during post-monsoon season from October to December will likely be ‘above normal’, or at least 12% more than what is usual for the three months combined. The average rainfall from 1971 to 2020 is about 33 centimetres. However, most parts of northwest India, some parts of northeast India and southernmost parts of India are likely to receive normal to below-normal rainfall.
In the IMD’s estimate, the southwest monsoon is expected to completely withdraw in the next fortnight.
Published - October 01, 2024 06:04 pm IST
