El Niño has already sparked much debate this season but we guess time has come for some reality check. The evolving El Niño has reached the threshold mark on April 24, 2017.
However, there are still three seasons - of three months each - to go in which the El Niño has to maintain above sea surface temperatures (SST), the prime criteria to declare an El Niño. Hence, there is still a long way to go before the declaration of an El Niño year but it holds the power to corrupt Monsoon in India even in the evolving phase.
Evolving El Niño
The phenomenon of abnormal warming of surface ocean waters in the equatorial Pacific, which occurs every three to seven years, is termed as El Niño. El Niño leads to warming of this sea surface temperature (SST) anomaly above 0.5°C.
Also Read: El Niño Returns: What else does Monsoon 2017 hold in store
The Oceanic Nino Index (ONI) is based on SST departures from average and El Nino is generally declared when ONI is greater than or equal to 0.5°C for overlapping 3 months. The most recent ONI value JFM (January – March 2017) is -0.2°C.
The Niño 3.4 index, which is linked with the Indian Monsoon, has now increased to positive. It was last seen at the value of 0.3 on April 17.
The Pacific Ocean had been showing a warming trend from the end of February 2015. Here’s a look at the Niño Index (in °C) as on August 24, 2017:
Looking at the trend, majority of the weather models are hinting towards the onset of El Niño by August. In fact, chance of El Niño which was below 50 % during the beginning of April has now increased to above 60% by mid-April.
The figure below will give a proper insight.
Image credit: NOAA
Any information taken from here should be credited to skymetweather.com
