Minimal impact of El Nino on rainfall: IMD DG Mohapatra
5 min read 26 Apr 2023, 11:40 PM ISTIn an interview, Mohapatra said that while some regions in west and central India and pockets of northeast India may experience below-normal rainfall, it will not apply to the entire country.
PremiumThe impact of El Nino on this year’s monsoon will be minimal, said Mrityunjay Mohapatra, director-general of India Meteorological Department (IMD). In an interview, Mohapatra said that while some regions in west and central India and pockets of northeast India may experience below-normal rainfall, it will not apply to the entire country. The comment comes amid concerns about slowing economic growth. The finance ministry on Tuesday flagged the downside risks to the official forecast of a 6.5% economic growth rate in FY24 because of elevated risks to the monsoon from the El Nino effect that could impact farm output and prices. Mohapatra said that El Nino is presently not severe but moderate and added that El Nino would likely develop by July, with its impact felt much later. He stated that IMD sticks to its 96% long-period average, normal monsoon prediction. Edited excerpts:
How will El Nino affect the monsoon and, subsequently, the water reservoir levels, in light of the latest data indicating a drop in storage levels in major reservoirs that has raised concerns about kharif crop prospects?
In the first monsoon forecast earlier this month, we said that precipitation in the June-September period is likely to be normal at 96% long period average with an error margin of +/-5%. Some regions in west and central India and pockets of northeast India may experience below-normal rainfall, which is unlikely in the entire country. The second stage forecasts will be issued by the end of May. In between, there is no other update. At present, La Nina conditions have turned into neutral conditions over the Pacific Ocean, and according to the latest climate model forecast, it is not a severe El Nino, which is likely to develop in the second half of the monsoon season, i.e. July. The impact of El Nino is expected to be felt much later. There is no one-to-one connection between El Nino and Indian summer monsoon precipitation. All El Nino years were not bad monsoon years. Six of the total 15 El Nino years during 1951-2022 had witnessed normal and above normal monsoon rainfall.
What is your view on the differing predictions by Skymet and IMD, with Skymet predicting 94% LPA, indicating a below-normal monsoon, and IMD predicting 96% LPA, indicating a normal monsoon?
I don’t want to comment on others. IMD uses a multi-model ensemble forecasting system, which is the best among the five global models. We make a consensus among them. Based on the consensus, we issue forecasts. The forecast covers the country as a whole and also different parts of the country.
According to IMD’s prediction, El Nino is seen to develop in July. How is it likely to influence the monsoon this year?
There are different factors that govern the performance of monsoon rainfall. El Nino is one of the factors. It is not the only factor that decides the monsoon, and we stand by our prediction. There are other factors, such as the Indian Ocean Dipole (IOD) and snow cover over the northern hemisphere and Eurasia. Therefore, we do not go by a single parameter. We go by a dynamic framework, considering all drivers influencing the monsoon. In addition to it, we have got a statistical ensemble forecasting system considering different parameters. Both models have a consensus of 96% LPA with an error margin of +/- 5%. This means it will be on the negative side but in the normal range.
Given that IOD directly impacts the quality of rainfall and IMD has predicted positive IOD, how do you expect this year’s monsoon to behave?
Neutral IOD conditions are present over the Indian Ocean and the latest climate models forecast indicates that the positive IOD conditions are expected to develop during the southwest monsoon season. Positive IOD is good for southwest monsoon in India.
In an earlier interview, you said the frequency of heatwave conditions is increasing because of rising temperatures amid climate change. Is it becoming a pattern?
No, if you look at this year, where is the heatwave so far? Only eastern India has witnessed it. So, it is not like every year, heatwave conditions will increase because of climate change. Some years, heatwave conditions can increase, and some years they can decrease. But yes, the overall trend hints that the frequency of heat waves is increasing due to climate change.
In east India, extreme weather conditions such as cyclones, torrential rainfall, and temperatures hovering around 42-44°C have been observed for a few years now. Is it attributed to climate change?
It is everywhere across the globe. Weather is a rapidly changing phenomenon, unlike climate. It changes within the day, from day to day and within a season and from year to year. So, there is nothing surprising about it.
IMD’s latest forecast indicates the possibility of another heatwave spell between 27 April and 3 May. How long will these heat waves continue?
Heatwaves can be felt anytime during the summer season. There could be temporary relief and, again, another spell. It is not that it is continuing for the entire season or heatwaves will not be there for the entire season. There could be another spell in the last week of April and beginning of May.
When is the onset of monsoon expected?
No forecast as of yet.
The World Meteorological Organisation warned that a trend of rise in sea levels, which hit a new record last year, would continue due to high levels of greenhouse gases. How extreme could the situation be?
If water levels rise, islands and coastal villages, towns, and cities will be impacted. It has happened in the past and can happen in the future. Extremity will depend on the vulnerability of the location, and people, among other factors. It is simply not because of meteorological factors. There are many other factors, like socio-economy and geography, that determine how extreme the situation may turn. Usually, the impact is expected to be more when a cyclone approaches as it will be a combination of cyclone and sea level.
East India and coastal areas of the country have been witnessing cyclones every year. What are the possible reasons behind such a weather occurrence?
Seasonal factors are involved. Sometimes it may come to Odisha, and sometimes it may go to Tamil Nadu or Andhra Pradesh. There is nothing to be surprised about. But if you compare cyclones occurring in pre-monsoon with post-monsoon season, frequency is less in pre-monsoon season. One or two cyclones develop during the pre-monsoon season. So, it is climatological. The frequency of cyclones is decreasing over the north Indian Ocean, especially over the Bay of Bengal.
