Despite El Nino cloud, IMD predicts normal monsoon

In the monsoon core zone that accounts for most of the rain-fed agriculture states, the forecast is normal

India Meteorological Department on Friday predicted a normal monsoon for the entire country notwithstanding "more than 90 per cent probability" of El Nino – a global weather disruptor -- developing during the season.

"Quantitatively, the southwest monsoon seasonal (June to September) rainfall over the country as a whole is likely to be normal with 96 per cent of average precipitation with a model error of 4 per cent on either side," IMD said in a statement. The long-period average calculated over a 50-year span between 1971 and 2020 stands at 87 cm.

But the forecast raised eyebrows due to the impending El Nino. "I am a bit surprised with the forecast, but IMD may be having its own reasons," a scientist told DH.

The monsoon is the lifeblood of India's $3 trillion economy. The four month long season delivers 70 per cent of the rain that the farmers need to water farms besides recharging reservoirs and aquifers. Nearly half of India's farmland doesn't have irrigation cover and depends on monsoon to summer crops like paddy, pulses, oilseeds, soybean and cash crops like cotton.

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Region wise, the southwest monsoon is most likely to be below normal over northwest India (less than 92 per cent of average) but normal over other three regions - central India, north east India and south peninsula (94-106 per cent of the average).

In the monsoon core zone that accounts for most of the rain-fed agriculture states, the forecast is also for normal rains.

While presenting the forecast D S Pai, a senior IMD scientist said there was more than 90 per cent probability of El Nino – an unusual warming of the Pacific Ocean adversely impacting the weather pattern worldwide – during the monsoon season and continuing till 2024 winter.

The dreaded weather phenomenon, typically associated with droughts and deficient monsoon in India, comes after three consecutive La Nina (cooling of the Pacific leading to bountiful monsoon) years benefiting India.

“Most of the drought conditions of the Indian summer monsoon rainfall are associated with El Niño (13 of the 18 drought years since 1901) indicating that about 72 per cent of the drought years are associated with the El Nino,” M Rajeevan, veteran weather scientist and former Secretary, Ministry of Earth Sciences told DH.

There is, however, no 1:1 correlation. Between 1951 and 2002, there have been 15 El Nino years out of which nine were below normal or deficient rainfall while the rest were normal or above normal. A major exception was 1997, which despite being an El-Nino year, led to 102 per cent of rainfall.

“The above-normal rainfall in 1997 was due to Indian Ocean Dipole, a temperature seesaw between Arabian Sea and Indian Ocean,” Pai said, noting that this year there had been a 70 per cent probability of a positive IOD, which would be beneficial for the monsoon.

But IOD, according to other experts, is not a reliable forcing agent unlike the El Nino, which is likely to cross the threshold value by August. “Predictions based on IOD are not always reliable,” said a scientist. The IMD forecast for June also remained below normal.