El Nino has been peaking in the recent weeks. The entire Eastern and Central Pacific remains unusually warm. It is possibly one of the strongest El Nino events on record, at least in the last 50 years. There are some signatures now - like the sea surface and sub-surface are showing cooling trends, though marginally.
Anomalous warming of Pacific Ocean, with a periodicity of 2 to 7 years and lasting for 6 to 8 months or at times even more, gives rise to El-Nino episodes. This warming results in reversal of trade winds which in turn modifies atmospheric circulation. The event has a bearing on global weather. However, the exact dynamics of governing forces and reasons behind this high impact event is still not well understood.
Global forecasters are expecting the El Nino to diffuse and accordingly, ENSO neutral likely during the second quarter of the year.
Equatorial Pacific is divided into four parts Nino 3, Nino 4, Nino 3.4, Nino 1+ 2, for Meteorological analysis. Any occurrence over Nino 3.4 is the most relevant for Monsoon in India.
Here’s a look at the surface temperatures anomalies in degree Celsius since December 2015: 
With respect to the Indian Monsoon, out of 26 El Nino events since 1900, around 50% have been followed by a neutral ENSO and 40% by La Nina years. There are speculations of La Nina conditions developing in the second half of 2016, during the Monsoon months.
Among El Nino, Neutral and La Nina conditions, there is no established pattern. There have been instances of La Nina following an El Nino year like 1969-70, 1972-73, 1987-88 and 2009-10. Also few cases are on record when we have observed three consecutive La Nina years like 1973-74-75 and 1998-99-2000. La Nina is invariably linked with strong Monsoon across Asia but it is not true in all cases. While the El Nino year 1997 experienced more than average rainfall, the La Nina years of 1974, 1999 and 2000 remained below normal. Yes, neither any La Nina year has ended up with a drought (<90%) nor an El Nino year experienced excess rainfall (>110%).
Click here to read the story, What is the impact of El Nino on Indian Monsoon
India has experienced two consecutive droughts of 2014 and 2015. The climatological probability of going through third drought in a row is the least. However, it is little too early to comment on the likely performance of Monsoon 2016.
January data is a fair indicator of probable conditions in the coming months and the numerical models are mostly pointing towards a gradual decline of El Nino. The credibility of data during February and March suffer due to the “Spring Barrier”. More authentic and reliable information emerges only in April. As of now, it is sufficient to say that neutral ENSO is quite likely during the Monsoon months and La Nina effect, if any, will be visible before the commencement of the pre-Monsoon season.
Featured Image Credit- Discovery
Main Image credit - Australian Bureau of Meteorology
