New Delhi: India is expected to receive above-normal rainfall in September, closing a monsoon season already marked by multiple disasters caused by heavy downpours across the country, the India Meteorological Department (IMD) said on Sunday.
According to the IMD, monthly average rainfall in September is likely to exceed 109 per cent of the long-period average of 167.9 mm. Most regions are forecast to receive normal to above-normal rainfall, while parts of the northeast and east, extreme south peninsular India, and some pockets of northwest India are likely to experience below-normal showers.
Addressing an online press conference, IMD Director General Mrutyunjay Mohapatra cautioned that intense rainfall in September may trigger landslides and flash floods in Uttarakhand and disrupt daily life in Delhi, south Haryana and north Rajasthan. “Many rivers originate in Uttarakhand. Heavy rainfall means many rivers will be flooded and it will impact cities and towns downstream. We should keep this in mind,” he said. He added that heavy rainfall is also expected in the upper catchment areas of the Mahanadi river in Chhattisgarh.
Mohapatra noted a slight increasing trend in September rainfall since 1980, except in years such as 1986, 1991, 2001, 2004, 2010, 2015 and 2019 when rainfall was deficient. He explained that the normal date for monsoon withdrawal from Rajasthan has shifted from September 1 to September 17, indicating that September rainfall activity has risen. “September is a transitional month when the season moves towards the post-monsoon phase. With the withdrawal delayed, the chances of interaction between the monsoon and western disturbances rise. The frequency of these disturbances also increases as winter approaches. As a result, September rainfall is showing an increasing trend,” the IMD chief said.
Between June 1 and August 31, India received 743.1 mm of rainfall — about 6 per cent above the long-period average of 700.7 mm. June recorded 180 mm, nearly 9 per cent above normal, with large surpluses in northwest and central India. July brought 294.1 mm, around 5 per cent above normal, driven by a 22 per cent surplus in central India. August added 268.1 mm, 5.2 per cent above normal.
Northwest India received 265 mm of rainfall in August, the highest for the month since 2001 and the 13th highest since 1901. The region recorded above-normal rainfall in all three monsoon months, with a cumulative total of 614.2 mm between June 1 and August 31 — about 27 per cent above the normal of 484.9 mm. South Peninsular India also logged 250.6 mm in August, 31 per cent above normal, the third highest since 2001 and the eighth highest since 1901. Overall, the region has received 607.7 mm since June 1, a surplus of 9.3 per cent against the normal 556.2 mm.
Mohapatra attributed the unusually high rainfall in northwest India to strong interactions between western disturbances and monsoonal low-pressure systems. He explained that low-pressure systems from the Bay of Bengal deviated from their usual course through Odisha, instead moving across Gangetic West Bengal, Jharkhand and Uttar Pradesh or via north Andhra Pradesh, south Odisha, Chhattisgarh and Telangana.
“Northwest India saw three such active interactions in August, which led to incidents in Dharali (Uttarakhand), Kishtwar (Jammu and Kashmir), Jammu and Mandi (Himachal Pradesh),” he said. The heavy downpour in northwest India also caused one of Punjab’s worst floods in decades, as swollen rivers and breached canals inundated thousands of hectares of farmland and displaced lakhs of people. In Himachal Pradesh, Uttarakhand and Jammu and Kashmir, repeated cloudbursts and flash floods triggered landslides, inflicting severe damage to life and property.
While the IMD has not observed a rising trend in cloudburst incidents, Mohapatra said a study by the Indian Institute of Tropical Meteorology indicates an increase in “mini cloudbursts,” defined as rainfall of 5 cm or more within an hour.
He added that active western disturbances between July 28 and August 14 brought heavy to very heavy rainfall over the western Himalayas and adjoining plains, causing flash floods and landslides in Uttarkashi on August 5, as well as major riverine floods in Uttar Pradesh and Bihar. The monsoon revived rapidly after August 14, with four low-pressure systems sustaining active conditions for 15 days in the latter half of the month.
According to the IMD chief, northwest India and adjoining Himalayan states experienced “extremely and exceptionally heavy rainfall events” between August 21 and 27 due to successive active western disturbances and strong monsoonal winds. Very heavy to extremely heavy rainfall was reported over east Rajasthan from August 22 to 24 and over Punjab and Haryana from August 23 to 26, while Jammu and Kashmir recorded severe flooding and landslides between August 23 and 27. Exceptionally heavy rainfall was also observed in Konkan and the ghats of Madhya Maharashtra on August 20, east Rajasthan on August 23, the Jammu region on August 27 and Telangana on August 28.
With PTI inputs