While the conditions for the monsoon’s onset over Delhi are in place, meteorologists are unable to set a precise date.
For well over a week now, the monsoon — that was to have reached Delhi on June 27-29 — has been on the threshold of the region with its northernmost limit over a stretch that spans Barmer, Aligarh, Meerut, Ambala and Amritstar.
“Conditions are ripe for the monsoon in Delhi and it is only a matter of time,” M. Mohapatra, Director-General, IMD, told The Hindu on Monday.
The latest forecasts, as of Monday morning, indicate no significant rain over the region for the next 24 hours and only chances of a “light drizzle” for the early part of the week.
With questions swirling on IMD’s failure to predict the monsoon in Delhi, the agency issued a statement late Monday arguing that the failure of their model was unprecedented.
“Such type of failure by numerical models in prediction of monsoon advance over Delhi is rare and uncommon. It is needless to mention that the IMD has predicted well with high accuracy about the advance of monsoon over Delhi quite accurately in the recent past years and also the advance of monsoon over different parts of the country during the monsoon-2021 accurately about four to five days ahead. The IMD is monitoring the situation continuously and will provide the regular updates on advance of monsoon into remaining parts of northwest India including Delhi.”
After the monsoon made its onset over Kerala on June 3, its southwest branch made a rapid journey upwards, prompting the IMD to forecast that the monsoon could arrive by June 15.
“We made a mistake with that. However after July 1, the IMD’s position has been that the monsoon would set in around July 10. We are seeing the setting in of the characteristic monsoon winds as well as low humidity and the clouds are there too. The rain is soon inevitable,” said Mr. Mohapatra.
‘Low pressure in Bay of Bengal ’
The main impediment to the monsoon had been the onset of westerlies. Now a rain bearing low pressure system in the Bay of Bengal was already pushing favourable easterly winds, he noted.
Normally, the monsoon covers the entire country by July 15 and Mr. Mohapatra said he was hopeful that this would happen.
The feeble rains northwest of India had led to the region staring at a 23% rainfall deficit. Until June 19, the all India rainfall was 40% more than what was normal but since then rainfall had weakened and declined, leading to the onset of ‘break conditions’, or a period of prolonged lull. From July 1-10, Delhi was expected to get 114.2 mm of rain but has only got only 44.1 mm, which is about 60% below normal. Central Delhi, IMD data shows, has the highest rain deficit at 93%, followed by South Delhi at 79%.
The overall monsoon rainfall from a surplus has turned to an 8% deficit. The low pressure in the Bay of Bengal has seen the monsoon revive in South and Central India. July and August are the most important monsoon months.
The IMD said earlier this month that monsoon rains over the country in July would be ‘normal’ or 96 to 104% of what it usually got. The northwest of India is relatively less dependent on monsoon rain for agriculture than Central and Southwest India.
