Further withdrawal of the Southwest monsoon from more regions along the northwestern parts of the country is not expected at least for another five to seven days, officials of the Indian Meteorological Department (IMD) said on Friday.
Last Tuesday, the IMD had declared the beginning of the monsoon withdrawal from southwest Rajasthan and small portions of Kutch. But some rains are likely over Kutch in the coming days, the weather models indicated.
For four days now, the monsoon withdrawal line has continued to pass along Khajuwala, Bikaner, Jodhpur and Naliya.
While declaring the monsoon withdrawal this year, the Met department officials had also stated that dry weather would prevail over Delhi, Chandigarh and Punjab. But the forecast fell flat with Delhi, Gurgaon and Noida receiving heavy rainfall on Thursday, prompting local administration in the national capital and adjoining areas to announce school closures and encourage work-from-home as roads remained flooded.
On Delhi rains, officials of Regional Meteorological Centre, New Delhi, said, “Western disturbances and presence of a trough in the mid-tropospheric levels along with the presence of a cyclonic circulation over northwest Madhya Pradesh, a remnant of the low pressure system, caused heavy downpour over Delhi and surroundings.”
The same cyclonic circulation, which is likely to prevail for another two days over the same region, and the western disturbances will cause heavy to very heavy rainfall (64.4mm to 204mm in 24-hours) over Uttarakhand, western Uttar Pradesh and Himachal Pradesh, all of which remain on an “orange” alert on Saturday and Sunday and on “yellow” alert until September 27. Northeast India regions, too, remain on “yellow” alert during the next five days.
Like monsoon onset over Kerala, the IMD declares commencement of the monsoon withdrawal only when its own key criteria are met. These include reversal of wind pattern and formation of an anticyclone system at 850 hectoPascal (hPa), cessation of rainfall for five consecutive days, drop in moisture levels or dry conditions along the northwest India regions. “However, on September 20, the anti-cyclone was absent although rainfall had reduced and moisture levels had fallen,” said a senior IMD official.
According to the Extended Range Forecast released on Thursday, there are chances of above-normal rainfall over northern Rajasthan during the September 23-29 period. And this raises doubts if the Met department declared the monsoon withdrawal in a hurry.
In recent years, monsoon withdrawal commencement has been delayed, mostly realizing towards either the end of September or early in October. The normal date for the commencement of the withdrawal is September 17.
According to IMD records for 2012-2022, monsoon withdrawal from northwest India took place in the first half of September only during three years – 2013 (September 9), 2015 (September 4) and 2016 (September 15). Two of the most delayed monsoon withdrawal commencement over the past 11 years were in 2019 (October 9) and 2021 (October 6).