The southwest monsoon is likely to begin retreating from the western parts of the country sometime mid next week, making it a delayed withdrawal this year.
Starting this year, the India Meteorological Department (IMD) is following a new calendar of monsoon onset and withdrawal. Accordingly, the normal date of commencement of withdrawal from western Rajasthan is September 17. Last year, the withdrawal started in the second week of October.
In order to declare monsoon withdrawal, it is mandatory that rainfall activity and moisture levels reduce significantly, in addition to the formation of an anticyclone system in the lower troposphere. Only when these criteria are met for five consecutive days does the IMD declare withdrawal from over a region.
“We are yet to realise withdrawal features, even though rainfall has reduced substantially,” said a meteorologist from the National Weather Forecasting Centre. “Models suggest monsoon withdrawal will commence by September 24.”
Around September 20, with a fresh low pressure system likely to develop over the North Bay of Bengal, widespread rain has been forecast over Odisha, Karnataka, Kerala, Konkan, Goa and Madhya Maharashtra during September 19-21.
“As a result of low pressure, the westerlies will strengthen and bring widespread rain mainly over south peninsular India, and some areas along the east coast,” the meteorologist added.
This means that this year, withdrawal from Central India and other regions will see a further delay.
Though rainfall in September for the country as a whole has been deficient, southern states have recorded surplus rain. The country-wide rainfall, as on September 18, was deficit by 12.6 per cent, whereas south peninsular India had recorded an excess of 75.6 per cent this month.
The cumulative rainfall for the country remained 6.7 per cent above normal.
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