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El Nino casts a shadow on 2017 monsoon

February 22, 2017 11:20 IST

Weather watchers said it can’t be known till May whether El Niño will impact the monsoon or not, reports Sanjeeb Mukherjee 

While it is gradually becoming clearer that La Niña -- which causes bountiful rain -- is unlikely during the monsoon this year, there is still no certainty as to what the status of El Niño, which causes less rain, will be.

El Niño, according to most models, is in an evolving state, something which makes predictions all the more difficult. An evolving El Niño (when sea surface temperatures move from cold to warm) and its impact on India’s southwest monsoon are both difficult to predict and any observation based on that is prone to correction. 

If supplementary conditions are not supportive, an evolving El Niño can cause much harm as was the case in 2014. “El Niño is at a developing stage and there is 50:50 chance of it growing into a full-blown one, therefore it needs to be properly watched as evolving El Niño is difficult to predict and so also its impact on Indian monsoon,” said Ajit Tyagi, former director general of the India Meteorological Department.

Earlier, this week, the Australian Weather Bureau in its latest weather update said that in marked contrast to last year, western Pacific sub-surface temperatures are up to 5° C more than they were at this time last year, indicating La Niña-like conditions are unlikely in 2017.

AWB is one of the most authoritative global agencies tracking El Niño and La Niña. On El Niño, most meteorologists and weather watchers seem to agree that if at all it appears, it would be somewhere around August, when just one month is left of India’s monsoon. If El Niño evolves during the latter part of the monsoon, it may cause much less pain than if it starts from the beginning. 

The World Meteorological Organization has said that there is a 35-40 per cent chance of El Niño reappearing this year and a 50 per cent chance of neutral conditions prevailing during the second half of 2017, which is after June -- the time when India’s southwest monsoon peaks. WMO is a specialised agency of the United Nations with 191 member states and territories. 

The state-run IMD is yet not willing to put its figure on El Niño’s time and the impact it would have on the Indian monsoon.

IMD said its first forecast expected sometime around April would make things clearer, but most weather scientists said it can’t be known till May whether El Niño will impact the monsoon or not.

For some weather watchers, an evolving El Niño is much worse than a full-fledged one and in the past, an evolving El Niño is known to have caused equal  harm to the southwest monsoon just like the full-fledged ones. Eighty per cent of El Niño years has seen below-normal rains, while 60 per cent have been outright drought years. 

“This is precisely what I have been saying that if weather models are predicting emergence of El Niño during the fag end of the southwest monsoon season, it means that El Niño would be evolving when Indian monsoon is at its peak,” Jatin Singh, CEO of private weather forecasting agency, Skymet Weather Services, said.

Singh said this is exactly what had happened in 2014 when India suffered a big drought and actual rainfall during the four-month southwest monsoon season stood at just 88 per cent of Long Period Average with all the four geographical sub-divisions in the country recording below-normal rains.

Photograph: Feisal Omar/Reuters

Sanjeeb Mukherjee