Rains to cover Andaman & Nicobar 6 days before onset date, says IMD

Monsoon is likely to reach the Andaman and Nicobar archipelago around May 16, nearly six days before its normal onset date, due to a cyclonic circulation in the Bay of Bengal, the India Meteorological Department (IMD) said on Wednesday.

Monsoon usually covers the Andaman and Nicobar islands around May 20. The onset date for Andaman and Nicobar was revised last month to May 22.

It then normally takes 10-11 days to reach Kerala, which marks the commencement of rainfall season in India.

The IMD is also likely to release the possible onset date over Kerala later this week.

A low pressure area, the first step in the formation of a cyclone, was formed over southeast Bay of Bengal and adjoining south Andaman Sea on Wednesday morning, the IMD said.

It is very likely to concentrate into a depression over the central parts of south Bay of Bengal on May 15 and further intensify into a cyclonic storm over southwest and adjoining west-central Bay of Bengal by the evening of May 16. “In association with the system (cyclone), the conditions will become favourable for advance of southwest monsoon over south Bay of Bengal, Andaman Sea and Andaman & Nicobar islands around May 16,” the IMD said.

Under its influence, adverse weather is likely over south and central Bay of Bengal and the Andaman Sea from May 15 onwards. The system is under continuous surveillance and the state governments concerned are being informed regularly, the Cyclone Warning Division added.

Mrutunjay Mohapatra, director general of the IMD, said the cyclone will aid in advancement of the monsoon, which is likely to be normal this year.

The onset date of monsoon over Kerala is June 1, which marks the commencement of the four-month long rainfall season in the country.

From this year, the IMD has also revised the dates of onset and withdrawal of the monsoon for several parts of the country based on the data from 1960-2019. The previous dates were based on the data from 1901 to 1940.    However, the onset date for monsoon over Kerala remains unchanged, Rajeevan said. In states like Maharashtra, Gujarat, Madhya Pradesh, Chhattisgarh, Telangana, Andhra Pradesh, Odisha, Jharkhand, Bihar and parts of Uttar Pradesh, monsoon will be delayed by 3-7 days compared to the existing normal dates.

For the national capital, the new normal onset date for monsoon has been revised from June 23 to June 27. Similarly, dates have been revised for Mumbai and Kolkata from June 10 to 11, and for Chennai from June 1 to 4.

However, over extreme northwest India, the monsoon will arrive a little early, on July 8, rather than the expected date of July 15. The new date for monsoon withdrawal from south India is October 15.