It is the beginning of the end for southwest monsoon this year, with the India Meteorological Department (IMD) announcing withdrawal of the monsoon from West Rajasthan on September 25. This is a week behind the normal withdrawal date of September 17.
As of Monday, monsoon rainfall over India was 5% below what’s usual for this time of the year.
Under the impact of an El Nino, India was staring at drought-like condition with August – a key monsoon month – registering a deficit of nearly 36% of what’s usual.
However excessive rainfall in September, nearly 16% above normal, over most parts of India – except the east and northeastern India – shored up the overall numbers to reduce India’s deficit.
September’s rainfall has been much above the IMD’s forecast. On August 31, the agency said rains would be ‘normal’ meaning a maximum of 9% more than the 16.7 cm that is due. Above-normal rainfall was most likely over many areas of northeast India, adjoining east India, foothills of Himalayas, and some areas of east-central and south peninsular India, the agency had said.
On the contrary, east and northeast India have received below-normal rainfall in September so far. South India and central India have got nearly 27% and 51% more rain than their usual quotas contributing to most of the September output.
Though the monsoon’s withdrawal begins from Rajasthan, it takes nearly until early- to mid-October for it to fully withdraw and be replaced by the northeast monsoon. However India officially only counts rainfall received from June 1 to September 30 as monsoon rainfall.
The IMD considers multiple criteria such as a lull in rainfall for five days, and the formation of an ‘anti-cyclone’ at a particular height in the atmosphere, to declare the withdrawal from Rajasthan.
