Monsoon withdrawal likely to begin from Sept 28: India Meteorology Department

Unlike last year, when Tamil Nadu grappled with water woes, this year the state has received bountiful and bonus rainfall from the Southwest monsoon. (Representational Image)

THE WITHDRAWAL of monsoon is most likely to commence from September 28 this year, with favourable conditions expected later this week. This, if realised, will make it the “most delayed monsoon withdrawal since 2009”, said officials at India Meteorology Department (IMD).

According to meteorologists, the normal date for monsoon withdrawal, which commences from extreme northwestern parts of Rajasthan, is September 1. However, monsoon generally does not begin its retreat till at least the second week of September, they added. IMD officials had started looking for signs of withdrawal along the extreme parts of Rajasthan after September 1, suggesting appropriate time for the start of southwest monsoon’s withdrawal journey.

“The key favourable factors, on the basis of which monsoon withdrawal is declared, include reduction in moisture levels, no rainfall activity for five consecutive days along the extreme western parts of the country. In addition, formation of an anti-cyclone in the lower troposphere is also crucial in order to fulfill the withdrawal criteria prescribed by the IMD,” added officials. The cumulative rainfall received in the country over the last week ranges between 140 and 210 per cent, making it an unusually wet September.

This has made experts draw parallels between the current monsoon and what is usually observed around July or August, when monsoon is in its most active phase. AK Srivastava, head of Climate Monitoring and Analysis Group, IMD, Pune, said, “As the monsoon continues to be vigorous in some parts of the country, even as in the fourth week of September, it is resembling like a mid-monsoon season.”

“The signs of withdrawal are long due and conditions are likely to form towards the end of this week,” he added.
Met officials said monsoon remained vigorous over Uttar Pradesh and Uttarakhand regions on Sunday, owing to a low pressure system prevailing over these regions. However, this system is most likely to weaken by Tuesday, they added.

The withdrawal is also crucial for the immediate following winter monsoon (northeast monsoon), which mostly caters to Tamil Nadu, Andhra Pradesh and rest of the regions along the east coast. Unlike last year, when Tamil Nadu grappled with water woes, this year the state has received bountiful and bonus rainfall from the Southwest monsoon. As on September 24, it has received 29 per cent surplus rainfall for the season. Tamil Nadu was among the three states in the country to be adjudged in the ‘’excess rainfall’’ category.

A senior official at IMD, Pune, said, “The delay in withdrawal of the Southwest monsoon also affects the onset of northeast monsoon. However, this year, as the east coast received excess rains, people will not mind a slight delay in the onset of the northeast monsoon.”