Skymet weather

CEO’s Take: Southwest Monsoon 2017, irrational exuberance or cautious optimism

May 16, 2017 9:33 AM |


Jatin-Singh-SkymetOn May 10, this news broke, “The prospects of the Monsoon have brightened because of the reduction in the likelihood of El Niño,” said IMD Director General K J Ramesh.

He added that the recent development on El Niño indicates that the Monsoon could be normal this year and could reach 100% of the long period average (LPA). He referred to the Bureau of Meteorology, Australia (BOM) and said that it had downgraded the occurrence of the El Niño and that the prospects of the Monsoon could improve “slightly.” This sent the Sensex and the nifty to new highs.

But the important thing to note is that the Monsoon forecast has not been updated, it still remains at 96% with 38% chance of normal. And, the second Monsoon forecast is slated for June.

I think this nuanced upgrade in the Monsoon without really updating the Monsoon forecast, came from the May 9 bulletin of the BOM, that is forecasting a drop in temperatures in Nino region 3.4 of the Pacific.

EL-Nino prediction --BOM
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This was somewhat also seconded by the ENSO update generated on May 8 that showed reduction in temperatures in Nino 3.4 from May itself.

EL-Nino predictions by CFS
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As encouraging as the signal is (as cooling of region Nino 3.4, is positively correlated with the Monsoon), one also has to consider full text of BOM as well as NOAA (National Oceanic and Atmospheric Administration).

In the May 9 update, according to the BOM, “The tropical Pacific is currently El Niño–Southern Oscillation (ENSO) neutral. Despite the likelihood for El Niño easing in some models, an event in 2017 cannot be ruled out".

Related Post: Countdown to Monsoon 2017 begins, likely to make timely onset over Andaman

The Bureau's ENSO Outlook remains at El Niño WATCH, meaning there is around 50% chance that El Niño may develop in the coming months. Some international climate models have reduced the likelihood of El Niño this year compared to last month.

However, five of eight international climate models still indicate that the tropical Pacific Ocean may exceed El Niño thresholds during the second half of 2017.

EL-Nino prediction --Models
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According to the El Niño Southern Oscillation (ENSO) update on May 8, “ ENSO-neutral conditions are favored to continue through at least the Northern Hemisphere spring 2017, with increasing chances for El Niño development by late summer and fall.”

The conclusion we have drawn from these two updates is that the El Niño signal is confused, but we still need to anticipate its appearance as there is a still a 50% chance that it might happen. And 50% is twice the climatological probability. Projections have become volatile, they might change again in the coming days, we need to wait and watch.

Related Post: Evolving El Niño reaches threshold, raises alarm

In this din, the IOD (Indian Ocean Dipole) update has been missed. The IOD positive forecasts are now weakening. According to the BOM, the IOD remains neutral and four out of six models are showing the formation of a positive IOD only by Winter. This is not a positive development, as an El Niño (if one was to form) is preponderant over a neutral IOD in Monsoon.

IOD Prediction

After the update, we are cautiously optimistic but at present not updating our forecast numbers. We don’t see reason to update our forecast because at 95% of the LPA (+/-5%), if things improve, we are covering till 100% of the LPA anyway. With the current data set available, we don’t think the Monsoon will cross 100%. And with a 50% chance for an El Niño, we need to account for a deficit if it happens. So therefore, we think 95 is a good number. We are still waiting for more data to trickle in.


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