Monsoon ends today, 7% excess rain recorded: IMD

Updated on Sep 30, 2022 05:19 AM IST

In 2021, monsoon rainfall was 99% of the long-period average (LPA), considered “normal”; in 2020, monsoon was 109% of LPA (above normal); in 2019, monsoon was 110% of LPA (above normal).

The states with the highest rainfall deficiency include Uttar Pradesh with 28% deficit; Bihar with 31%; Jharkhand 21%; Manipur 47%; Mizoram 22% and Tripura 24%.(PTI)
The states with the highest rainfall deficiency include Uttar Pradesh with 28% deficit; Bihar with 31%; Jharkhand 21%; Manipur 47%; Mizoram 22% and Tripura 24%.(PTI)
By, New Delhi

The southwest monsoon is set to officially come to an end across India on Friday after recording around 7% excess rainfall, making 2022 an “above normal” season. This is the fourth consecutive year that India’s monsoon has been in the “normal” or “above normal” category.

In 2021, monsoon rainfall was 99% of the long-period average (LPA), considered “normal”; in 2020, monsoon was 109% of LPA (above normal); in 2019, monsoon was 110% of LPA (above normal).

To be sure, while the overall national rainfall deviation remained relatively minor, this year’s monsoon was characterised by erratic rainfall, particularly towards the end of the season. The final two weeks of September, a period which generally experiences the weakest leg of the monsoon, saw heavy rainfall in a majority of northwest India.

Despite this, east and northeast India saw 18% rain deficiency, according to data maintained by India Meteorological Department (IMD). There is 1% excess rain over northwest India; 19% excess over central India and 22% excess over peninsular India.

The states with the highest rainfall deficiency include Uttar Pradesh with 28% deficit; Bihar with 31%; Jharkhand 21%; Manipur 47%; Mizoram 22% and Tripura 24%.

LPA is the average rainfall calculated for the 1971 to 2020 period, which is 87 cm of rain between June to September .

A good monsoon ensures adequate sowing and a bountiful harvest, which in turn helps put a lid on food inflation by increasing domestic output of a variety of goods and commodities. This is particularly crucial this year, as the world is currently reeling under high inflation (especially of food grains) largely due to the war in Ukraine.

Monsoon rainfall less than 90% of LPA is considered “deficient”; 90 to 96% of LPA is considered “below normal”; 96% to 104% is “normal”; 104 to 110% is considered “above normal” and over 110% of LPA is considered “excess”.

The last time India saw four consecutive years of normal or above normal monsoons was 14 years ago, between 2005 and 2008, according to IMD officials. The period between 1993 and 1999 also saw only normal or above normal monsoon years according to IMD officials.

While presenting its long-range forecast on June 1, IMD had said that monsoon rainfall this year was likely to be “normal” at 103% of LPA a model error of +/-4%.

On Thursday, IMD officials said their forecast for the season was quite accurate.

“We are likely to end the season with 107% of LPA which is in the ‘above normal’ category. If you remember we had forecast monsoon rainfall is likely to be 103% of LPA with a model error of +/-4%. We have met that criterion,” said M Mohapatra, director general, IMD.

He added that areas in the Indo-Gangetic plains, in particular, saw high deficiency. “States in the Indo-Gangetic plains have good irrigation, so farmers could continue with their crop. However, during the last spell of intense rain between September 20 and 25 over northwest India, there may have been some damage to standing crop in west Uttar Pradesh, Haryana etc. But the rains were beneficial for hydrology and storage of water which can be of use later,” said M Mohapatra, director general, IMD.

Independent experts said the rare “triple-dip” La Nina, a large-scale cooling of surface temperatures in central and eastern equatorial Pacific Ocean which is associated with strong monsoon and colder winters in India, ensured a good quantum of rainfall over the country. The protracted La Niña event which started in September 2020 will last until at least the end of 2022, becoming this century’s first “triple-dip” La Niña, spanning three consecutive northern hemisphere winters (southern hemisphere summers), World Meteorological Organization said in August.

“La Nina is a very important factor for the four continuous normal to above normal monsoons. We have to see what happens next monsoon but La Nina may extend up to 2023. Another factor is that we may be entering a wet epoch from dry epoch. A lot of rain-bearing low pressure systems formed but to the south of the normal position which brought significant amounts of rain to central and peninsular India in July and August but there was rain deficiency along the foothills of Himalayas. Break monsoon conditions were very few and brief which is a sign of an active, good monsoon,” explained DS Pai, director of the Institute of Climate Change Studies and former climate scientist at IMD Pune.

There is a decrease of 12.0 mm in monsoon and 16.8 mm in annual rainfall from 1961 to 2010 to 1971-2020. The decrease is part of natural multidecadal epochal variability of dry and wet epochs of all India rainfall, IMD said in a statement in April.

“Presently the southwest monsoon is passing through a dry epoch which started in the decade of 1971-80. The decadal average of All India southwest monsoon rainfall for the decade 2011-20 is -3.8% of the long-term mean. The next decade (2021-30) is expected to become closer to neutral and southwest monsoon would enter the wet epoch from the decade, 2031-40,” IMD had said.

On several flooding and extreme rainfall events during this monsoon recorded in Assam, Gujarat, parts of Maharashtra and some parts of central India, Pai said “Climate change is increasing the frequency and intensity of heavy rainfall events. When low pressure systems form, their impact is aggravated by climate change.”

“The geographical distribution was not good for the farming community this monsoon. None of the low-pressure system moved northwest-wards except the last one. They moved in westward direction leading to excess rainfall over central and peninsular India during the season.

As of Thursday, monsoon had withdrawn from all of Punjab, Chandigarh and Delhi, and parts of Jammu & Kashmir, Himachal Pradesh, Uttar Pradesh, Haryana and Rajasthan, IMD has said.

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