El Nino may set in by 1st half of monsoon: US forecast

Strengthening the forecasts of an El Nino forming this year, the latest update from the US national weather agency says the weather condition linked to deficient monsoon rains in India may set in as early as the June-Aug trimester, with a one-in-three chance that it would go on to develop into a strong event.

The update released on Thursday by Climate Prediction Center under the US National Oceanic and Atmospheric Administration predicted a 62% chance of an El Nino emerging by June-Aug - corresponding with the Indian summer monsoon - rising to over 80% in subsequent months.

This is a significantly higher probability than the agency's previous update on Feb 12, which had given a 52% chance of an El Nino setting in by July-Sept, rising to around 60% in later months.

"Although a clearer picture will emerge in the next two months, we can be reasonably certain that an El Nino will set in this year, given the consensus among major wea-ther agencies across the wor-ld, including IMD. Given this weather condition's link with depressed monsoon rainfall in India, govt should prepare accordingly," said veteran meteorologist M Rajeevan, former secretary of the Union earth sciences ministry.

El Nino is the warm phase of the central-east equatorial Pacific Ocean waters that corresponds to changes in wind patterns. Together, these profoundly impact weather around the world.

Since 1980, there have been 14 El Nino years, of which nine have corresponded with deficient monsoons in India with rainfall at least 10% below long period average. In another year, 2018, the monsoon was close to deficient at -9.4%.

"The connection between El Nino and poor monsoons in India is strong, although there have been exceptions. The most notable example is 1997, when the monsoon was normal despite a super strong El Nino," Rajeevan said.

In 1997, a strong positive phase of what's known as the Indian Ocean Dipole (IOD) is known to have counteracted El Nino. IOD is a measure of the temperature difference between surface waters in the ocean's east and west regions. Forecasts suggest IOD is likely to be positive this monsoon.

"IOD forecasts are much less reliable and its effect on the Indian monsoon is not robust and consistent. Each season has dynamics that are unique," Rajeevan said.

The US update contrasts with a release from European Centre for Medium-Range Weather Forecasts, which predicted a more rapid warming of the Pacific with a possibility of a very strong or 'super' El Nino later this year, potentially setting the stage for unprecedented heat waves.

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