India Meteorological Department (IMD) has said that a cyclonic circulation each forming over the Bay of Bengal this week and the next would keep the monsoon active over East and Central India and not allow the Southwest monsoon, now in its last month, to start withdrawing until its very end.

The seasonal monsoon trough over land across Northwest, Central and East India now extends beyond Indochina and into the West Pacific. Thus, it connects the West Pacific and the Bay of Bengal, setting up a scenario where the monsoon is getting favourably impacted by both water bodies.

This is what gives rise to cyclonic circulations/low-pressure areas in the Bay. Already, a cyclonic circulation has formed over the East-Central Bay and adjoining Myanmar coast. It will move towards the Odisha-West Bengal coasts and further across land over East and Central India.

Cooler, wetter autumn

The Application Laboratory of the Japanese national forecaster Jamstec has predicted that India is likely to witness a cooler autumn (September to November) this year on the back of a brewing La Nina in the tropical Pacific and a weakening negative Indian Ocean Dipole. Rainfall for the country during the 2021 autumn is expected to be normal to above normal, according to the Japanese agency.

Back home, there is likelihood of another cyclonic circulation forming over the East-Central Bay during the next week (September 22-29), with a near similar pattern of movement as the first one during the ongoing week. Both will be accompanied by a belt of heavy to sustained heavy to very heavy rainfall.

Rainfall during the last two weeks of the month (September 16-22 and September 23-29) may stay above normal over Northwest and Central India. It will be near normal over East and Northeast India and below normal over the South Peninsula during the first week. In the second, it would be near normal over the South Peninsula and below normal over East and the Northeast India.

Wet over Northwest, Central India

Fairly widespread rainfall with isolated heavy to very heavy falls is forecast over West Madhya Pradesh on Friday and isolated heavy falls from Saturday to Tuesday. Isolated heavy falls are forecast over Uttarakhand from Sunday to Wednesday.

Fairly widespread rainfall with isolated heavy falls is likely over East Rajasthan and adjoining Gujarat on Friday and may increase in intensity with isolated heavy to very heavy falls from Saturday. Rains may scale up over West Rajasthan, Saurashtra Kutch for three days into the weekend and next.

More rain for East India

In the East, rainfall may increase over Odisha and plains of West Bengal with fairly widespread to widespread rainfall and isolated heavy falls over above areas until Monday and over Chhattisgarh, East Madhya Pradesh and Jharkhand from Monday to Wednesday.

Light to moderate isolated/scattered rainfall activity likely over rest parts of country during most days of the ongoing week (September 16-22). There is likely to be an increase in rainfall activity along the Konkan region with isolated heavy falls towards second half of the week.

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