IMD declares onset of southwest monsoon over Andaman Sea, Nicobar islands

In 2023, the southwest monsoon onset over the South Andaman Sea was realised on May 19.

The blue line indicating the region where the southwest monsoon onset has been realised (Photo credit: IMD)

The IMD follows certain criteria for considering monsoon advancement and onset. As per the IMD, the strength of westerly winds measured in the lower tropospheric levels (upto 3 km) increased to about 20 knots. The southwesterly winds prevailed up to the height of 4.5 km above the mean sea level over the region. There was an increase in cloudiness and the Outgoing Longwave Radiation(OLR) over the area was less than 200 watts per sq metre.

“There has been widespread rainfall over the Nicobar Islands during the past 24 hours. Considering all the above satisfied conditions, southwest monsoon has advanced into some parts of Maldives and Comorin area, some parts of South Bay of Bengal, Nicobar Islands and South Andaman Sea,” the IMD said.

The IMD has forecast that the monsoon will advance over Kerala on May 31. According to the rainfall prediction, India’s seasonal rainfall is expected to be 106 per cent of the Log Period Average (880mm for 1971 – 2020 average).

The Met department has issued a ‘yellow’ warning over the Andaman and Nicobar islands till May 22.