Monsoon 2015 to be unaffected by El Nino

 

Most of the weather agencies across the globe are speculating the performance of Indian Monsoon 2015. Weather scientists from the US, Japan and Europe expect Indian monsoon to be normal this year. However, the statement does not come without riders about El Nino. Skymet issued the first forecast of monsoon 2015 by February end and expected it to be normal. The chances of drought or excess rain are least or rather negligible.

To know what is El Nino, click here.

El Nino, which started evolving around the spring season last year, remained precarious during the monsoon season. The fall of last year saw the NINO index reaching threshold value of 0.5 in NINO 3.4 region and sustained through the spring of 2015 so far. However, the maximum value of the index has been 0.7, achieved during the winter months and its latest value as of 16 March, 2015 is 0.5. For historical purposes, El Nino episodes are defined when the threshold is met for a minimum of five consecutive overlapping seasons of three months each. Read the article: El Nino scare abandoned for a better understanding of the above statement. The figure on the left shows the latest weekly SST departures.

Present State of El Nino 

 

In the current scenario, four such successive episodes have already been recorded and its possible continuation in the next season, from January to March 2015 will qualify 2014-15 as an El Nino year. However, the state of El Nino continues to be mild. Also, the entire Pacific Ocean has never remained warm since January 2015. On the contrary, Nino 3 and Nino1+2 have shown signs of cooling. Under such conditions, the past records suggest that El Nino conditions will continue till Indian summer and collapse thereafter, during the Southwest Monsoon season.

 

 

 

 

 

 

 

 

 

 

Weak El Nino during Indian summer 2015

According to US agency NOAA, there is a 50- 60% chance of El Nino during Indian summer. The Australian Bureau of Meteorology expects about 50% chance of El Nino forming in 2015. The European Center for Medium Range Weather Forecast also place the chances at 50%.  However, traditionally, El Nino predictions made in March often suffer from low credibility, possibly on account of ‘spring barrier’.

Evolving conditions indicate only a weak El Nino during Indian summer and is considered inconsequential for the monsoon rains.  Yes, a combination of weak El Nino and a negative IOD (Indian Ocean Dipole) could have adverse effects. IOD refers to change in temperature difference between the western and eastern parts of the Indian Ocean.  A warmer western Indian Ocean is linked with poor Indian monsoon. As of now, IOD remains neutral and so does not pose any threat to the monsoon rains.

The Southwest Monsoon rains are invariably assumed to be below normal during the El Nino years. A strong El Nino has resulted in severe droughts on few occasions. However on the brighter side, monsoon rainfall has been recorded normal or even above normal in El Nino years, on some occasions. Poor rains or even drought occur in the absence of El Nino.  Skymet will issue an update on the likely performance of Monsoon-2015 around mid-April. This forecast can be considered authentic and reliable.

To know what is Monsoon, click here. 

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