El Nino effect will significantly reduce rainfall in July, says Skymet MD

Jatin Singh, managing director of Skymet (Mint)
Jatin Singh, managing director of Skymet (Mint)

Summary

According to Jatin Singh, managing director of Skymet, IMD may have some limitations in presenting its first forecast as ‘below normal’

Will it be a normal monsoon this year? Yes, according to official forecaster India Meteorological Department (IMD), but no, as per private weather forecaster Skymet. According to Jatin Singh, managing director of Skymet, IMD may have some limitations in presenting its first forecast as “below normal." El Nino years are low on rainfall, and the positive effect of the Indian Ocean Dipole (IOD) won’t be strong enough to override its impact, Singh said in an interview. Edited excerpts:

Skymet forecasted a 94% long-period average monsoon forecast, considered below-normal rainfall, while IMD expects monsoon to be normal at 96% of LPA this year. What is your take on this?

Ninety-six percent LPA is the lowest range forecast in the normal rainfall category. If you look at below-normal rainfall and drought probabilities, IMD predicts it to be 51%, while Skymet anticipates a probability of 20% drought-like situation and 40% below-normal precipitation this year.

Both IMD and Skymet talked about El Nino and Indian Ocean Dipole (IOD), and as per our predictions, El Nino is seen to be dominant. In the two decades of my career, the monsoon was good in 1997 and 2019 despite El Nino.

Skymet’s weather forecast is seen to be wrong twice, once in 2015 and the other in 2019. What causes such errors?

There is always a probability for forecasts to be wrong. Predictions not only by Skymet but also by IMD have been wrong before. There might be an error. I have been forecasting for 11 years, and I have got two wrong. There is always some probability of IOD superseding everything else, but that probability is low.

We are not able to model IOD accurately. It is extremely erratic. The spoiler in the monsoon forecast is the IOD. If the IOD becomes too strong, the monsoon will be normal, which happened in 2019, despite the El Nino phenomenon. It happened in 2021 and 2022, which were La Nina years. Negative IOD weakened the monsoon, and then it started becoming neutral. The Indian Ocean is warm enough that it does not matter if it ends or weakens. In 2012, the monsoon was about 92% of LPA, and 2015 was a drought year. In both years, we had the IOD positive, but the positive IOD did not have a significant impact. In 1997 and 2019, EL Nino was strong, but the strong IOD could weaken the impact of El Nino. That happens, but not often.

What is the modelling system that Skymet follows for the monsoon forecast?

There are two ways of doing it. One way is a dynamic model, which is a climate forecasting system. This is a global model which predicts what it is going to have, especially in monsoon. We have been using it, and we are simultaneously doing bias correction to fix it. The other way is a statistical model. It examines the correlation between El Nino and IOD with the monsoon. We look at whether dynamic and statistical models are converging or diverging.

What is the condition of IOD right now, and how is it likely to behave in the second half of the monsoon?

A positive IOD contributes to a good monsoon, but it needs to be strongly positive. This means the difference in temperature between the eastern and western parts of the Indian Ocean should be more than one degree Celsius. Currently, the IOD is about +0.1 degree Celsius, which will take time to gather pace. So, in my opinion, IOD may not be strongly positive this year, but it will be positive. IOD is not anticipated to be so positive that it will weaken the impact of El Nino as it did in 2019.

Considering past El Nino experiences, how do you expect El Nino to influence the southwest monsoon this year? What is the position of El Nino right now?

El Nino is warming the Pacific Ocean. Currently, it is still at the neutral stage. There are three components. One is La Nina, the second is El Nino, and the third is neutral. 100% gets divided between these three. Currently, El Nino has a 30% share, while La Nina has a similar share, and the rest is neutral. It is dominated by neutral at this moment. As we proceed to May, the contribution of El Nino is seen sharply rallying, and when we enter June, the onset of monsoon, it is likely to go up further, and the contribution of El Nino may reach up to 80% or even exceed it during August and September, which are core monsoon months. This will significantly reduce the rainfall amount starting July, and more drop in August and September is expected. We expect the second half of the monsoon to be harsher than the first half. In June, it may not be very hard. Rainfall may possibly be normal in June, but as we enter the crucial period of monsoon, the impact of El Nino is expected to be felt.

How severe can the impact of El Nino on the southwest monsoon be this year?

This year, the onset of the southwest monsoon may be timely. As far as El Nino influencing the monsoon is concerned, overall monsoon precipitation performance is expected to be impacted. Sixty percent of cases land up as drought as per the past data. The past three decades’ data show the number of droughts has increased in connection with El Nino. Earlier in the 1950s and 1960s, there was more than one year when rainfall was normal despite El Nino. That is how IMD keeps saying all-drought years have been El Nino years, but all El Nino years have not been drought years since 1951. It is a fact that despite El Nino, rainfall was normal in some years. The majority of this was in the 1950s and 1960s. In the recent past, 1997 was the only year when El Nino did not cause drought.

El Nino has been causing drought from 2001 onwards. We had witnessed below-normal rainfall, with a 91% long-period average in the 2018 monsoon.

You can read El Nino based on the climatology and past records. As per the past records, El Nino impacts more central and northern regions of India. About 50% of our agricultural area is dependent on rainfall, and out of which, most areas are part of central India and possibly some eastern regions. Maharashtra, Madhya Pradesh, Chhattisgarh, Bihar, Jharkhand and eastern parts of Uttar Pradesh depend largely on monsoon rainfall. North India also gets impacted, but the weather is resourceful there. They absorb because of their rich resources. There is not much hue and cry in terms of rainfall shortfall. There is a deficiency, but not as much as in other regions like pockets of Gujarat, Madhya Pradesh and, Vidarbha, Marathwada of Maharashtra.

Is it possible to get an estimation of the distribution of rainfall on a monthly basis during June-September?

The start of the monsoon may be fine. June is seen to witness 99% rainfall, which is good. Gradually, as El Nino gains strength and in the second half IOD declines, precipitation is seen reducing month-on-month in July, August and September.

The weather has been changing drastically these days. We have seen a spell of extreme heatwaves across the country. This week, we got a respite due to cooling temperatures and light to moderate rainfall. Another bout of heatwave is predicted next week. What are the reasons behind such weather occurrences?

The concept of climate change is not well-understood. When I say this, I am trying to tell you that nobody really knows how atmospheric chemistry has changed over the decades. Why are we having hailstorms suddenly in the central and south peninsula? Why are we getting such extreme weather? Why is the rainwater dropping and size increasing? The average rainfall remains the same, but the number of rainy days has gone down, which is dangerous because it creates a lot of precipitation in compressed time. The assumption is that we understand climate, but we don’t. We are not even going to be within the threshold of 1.5°C, which has also gone out of the window.

We barely know the mechanics of weather forecasting in climate because we have not sampled it enough or computing is limited in terms of the number of days as well as the effectiveness of the human race taking out weather estimates well before time. People are talking about mitigation, but we need to work on adaptation.

How extreme can climate change become?

It has been extreme for years. Sufferings by farmers and stagnant food production have been going on for years. Climate change has beaten India. Parts of Odisha are already underwater. If you talk to farmers, they will tell you that crops do not grow as easily as they would 30-35 years ago. Water availability is becoming worrisome. Rain distribution is becoming uneven. So, climate and weather have become challenging for the Indian agriculture sector for a generation now.

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