Six weeks of this year’s southwest monsoon season are over and it has been a roller coaster ride. Sridhar Balasubramanian, associate professor with the mechanical engineering department at IIT Bombay was our special guest on Gaon Connection’s Gaon Cafe to discuss the monsoon’s performance so far and what lies ahead.
Three days back, on July 13, the southwest monsoon finally covered the entire country, including the national capital Delhi where the arrival of monsoon was delayed by over two weeks.
As against its normal date of July 8 for covering entire India, this year’s monsoon took five extra days to cover the country. Similarly, the arrival of monsoon was late by 16 days in Delhi and the IMD termed its failure to forecast the monsoon in Delhi as a ‘rare and uncommon’ error.
Meanwhile, several districts of Himachal Pradesh and Jammu & Kashmir have faced flash floods in the past couple of days.
To understand the many moods of monsoon 2021, Gaon Connection’s ‘Gaon Cafe’ programme had a special guest, Sridhar Balasubramanian, who is associate professor with the mechanical engineering department at the Indian Institute of Technology (IIT) Bombay. He is also an adjunct faculty member at IDP Climate Studies, IIT Bombay.
Talking with Nidhi Jamwal, deputy managing editor of Gaon Connection, about the monsoon 2021, Balasubramanian said that like every year, this year’s monsoon was also a “roller coaster ride”. The southwest monsoon season in India stretches from June to September, and so far its six weeks are over.
Before moving on to explaining what caused the delay in arrival of monsoon in Delhi, Balasubramanian described the genesis of monsoon currents.
“During the peak summer months, near the equator, monsoon currents start strengthening and propagating northwards. The monsoon current then splits into two branches — Arabian Sea branch and Bay of Bengal branch,” he explained in Gaon Cafe.
The Arabian Sea branch covers the west coast of India and parts of central India. Whereas the Bay of Bengal propagates into Tamil Nadu, Andhra Pradesh, Odisha, West Bengal and the northeastern states, he said.
He went on to describe how the north west India region is always in a very tricky situation. “Both these branches of the monsoon current should combine so that the monsoon propagates into Uttar Pradesh, Haryana, Delhi, parts of Rajasthan, and Jammu & Kashmir. This year, Bay of Bengal branch was quite active. However, Arabian Sea branch lost the momentum. After June 15 it was very inactive,” Balasubramanian informed.
Models were expecting that both the branches of the monsoon would converge over Delhi around June 16. But it did not happen, said the associate professor. “The Arabian Sea branch lost its energy and once that happens, we went into a break phase as the Bay of Bengal branch of monsoon had also reached the foothills of Himalayas. Thus, rains reduced for the entire country except Bihar, parts of Uttar Pradesh and northeast India, he explained.
On being asked by Jamwal what then finally led to the monsoon coming into an active phase, Balasubramanian said that around June 19-20, both the branches of monsoon had degenerated.
“Once the monsoon degenerates, you have to wait for ten days or two weeks for the fresh monsoon pulse to come from the equator and slowly move upwards. And that is when both the branches will re-energise. That started happening around the first week of July or near July 10, which resulted in the arrival of monsoon over north India and Delhi,” he informed.
Jamwal went to ask Balasubramanian questions around the recent flash floods in Dharamshala in Himachal Pradesh and parts of Jammu & Kashmir, and if monsoon rainfall patterns were changing and the reason behind it.
Balasubramanian also shared his unofficial forecast of how monsoon 2021 season is likely to end — normal, below normal or above normal rainfall?
Watch the full episode of Gaon Connection’s Gaon Cafe!