Cloud over monsoon gets bigger: Longer El Nino is new forecast

The previous such advisory, issued in March, had forecast a 50 to 60 per cent chance of an El Nino continuing through summer.

The US weather agency, in its latest bulletin, has forecast an enhanced probability for an El Nino event developing in the equatorial Pacific Ocean, giving rise to fears that the monsoon rainfall this year might be adversely affected.

As per an advisory issued by the Climate Prediction Centre of the National Oceanic and Atmospheric Administration of the United States Thursday night, there is a now a 70 per cent chance that an El Nino event will continue till the summer of Northern Hemisphere.

El Nino is a term used to describe a condition in which ocean temperatures in equatorial Pacific region become unusually warm. It is known to have an impact on the Indian monsoon, besides affecting a lot of other weather events worldwide. There is a strong correlation between an El Nino event and a poor monsoon.

The previous such advisory, issued in March, had forecast a 50 to 60 per cent chance of an El Nino continuing through summer.

But the latest advisory also talks about the chance of an extended El Nino this year — a possibility that was reported by The Indian Express on Thursday. It says there was a “greater than 60 per cent chance” that the El Nino will continue through autumn, and even till year-end.

“Compared to last month, more models predict El Nino to continue throughout 2015,” it said.

An extended El Nino is not good news for the Indian monsoon. There have been 19 El Nino events in the past 65 years, two of which were prolonged El Ninos — the kind which might happen this year. On both those occasions, India witnessed two consecutive years of drought.

The NOAA advisory said the kind of conditions that are currently prevalent in the Pacific Ocean indicate that the El Nino would not be very strong, meaning the warming of the surface temperature would not be very considerable. A stronger El Nino is known to have a greater adverse impact on the Indian monsoon.

However, the advisory also admits that at this time, “there is also considerable uncertainty as to how strong this event may become”.

As of now, the temperature rise in areas where El Nino develops is projected to be in the range of 0.6 to 1.4 degree celsius. The two areas which are known to have maximum impact on the monsoon are forecast to have temperature rises of 0.7 and 1.1 degree celsius.

Scientists in India say a temperature rise of less than 1 degree celsius does not generally result in any significant impact on the monsoon.

But sometimes the temperature rise can be as high as 4 to 5 degree celsius.

Source:: Indian Express