‘El Nino hit August rains, will remain strong till December’: IMD chief

We have seen deficient rainfall in August after excessive precipitation in July. What is your estimated rainfall departure for August as we are almost at the end of the month?

We are not expecting much rain in the remaining period of August. It will be below-normal precipitation. While presenting the monthly forecast for August, we said it could be 92% long period average when asked, but we do not predict the actual value. Rain in August became below normal as predicted at the beginning of the month, but it became extremely below normal, that is above 30% now.

We have observed uneven rainfall distribution this season, and the East and North-East have suffered. What is your view?

Monsoon has been good and balanced this year as far as distribution is concerned. It gave good rainfall over North-West India in June and July as well as in August in some states i.e. Jammu and Kashmir, Himachal Pradesh and Uttarakhand. Peninsular region also got good rain in July. In the case of East and North-East India, they did not get adequate rainfall in June and July, and it was highly deficient. The deficiency went up to 45-50% in East Uttar Pradesh, Bihar, Jharkhand and West Bengal, but rainfall picked up in these regions in August and now it is only 25% deficient. Therefore, I’d say it is balanced partially. If you look at subdivision-wise, 25 of total 36 got normal or above-normal rainfall. Last year, till the end of August, East Uttar Pradesh, Bihar, Jharkhand and West Bengal experienced less rainfall but this year, it is better than last year. If you look at Kharif cultivation, it is more than last year. Except Kerala, water reservoirs levels are good.

What is your rainfall forecast for September?

The forecast will be issued on 31 August.

What is the status of El Nino and the Indian Ocean Dipole (IOD)?

At present, it is a weak El Nino condition and may become moderate. El Nino is gaining strength gradually. Our forecast was weak to moderate conditions in the season, which is happening. El Nino is expected to continue till December this year. IOD is neutral at present and just entered the positive side. So, in September, it is expected to be positive.

When do you expect the south-west monsoon withdrawal process to begin?

No forecast as of yet. We do not have a long forecast for monsoon withdrawal. We give the forecast five days ahead on a day-to-day basis.

This monsoon has witnessed extreme variations and transitions. What are the factors behind this?

This is part of monsoon variability. It is nothing new that has happened this year. Monsoon is random in nature. Monsoon rainfall varies from year to year and within the season. What is important is how far we can predict or detect that variation. You cannot control the variation as it is part of natural variations, and it has been there for a quite long time.

Over time, the country has improved observations and modelling and forecasts and accordingly, we have started to predict the probability of normal, below-normal or above-normal rainfall in different parts of the country. So, we have been largely able to capture the trend whether it will be on the higher side or lower side of the normal, but predicting the absolute value, whether it will be so and so percentage is still difficult, especially when it becomes extreme. For example, for July, we said it will be on the positive side of the normal and it turned out to be true. Similarly, for August, we predicted precipitation to be below normal, but it became highly below normal. Now, it is above 32%. Therefore, the trend is being captured but the absolute figure is still to be captured well.

Extreme cases are difficult to capture; whether it is day-to-day extreme or seasonal or monthly extreme. Henceforth, more research is required and there are institutes under the ministry of earth sciences working on it. This is an ongoing process. If I compare two decades ago with today, we have come a long way with respect to the seasonal and monthly forecasting. We can provide a good assessment of the pattern of rainfall expected, which helps many in water management, agriculture management and industrial-management fields because the monsoon rain makes up over 70% of India’s total rainfall. As far as extreme events are concerned, yes, we need to work to further improve seasonal extreme forecasts and people are working towards that.

What causes extreme variations in rainfall?

There are different scales of processes. Monsoon is a large-scale process worldwide. Therefore, global scale phenomena can influence monsoon. El Nino or La Nina is one of the global phenomena. El Nino developed in July, and weak El Nino conditions are prevailing. In general, El Nino has a negative impact on monsoon rainfall that is seen. Although it developed in July, it could not have an impact as atmospheric conditions were not influenced by El Nino. But in August, atmospheric components are influenced by El Nino. Therefore, wind patterns are responding to El Nino developing over the Pacific Ocean.

The second is Madden Julian Oscillation. There is an oscillation in the atmosphere along the Equator, especially leading to sometimes increase or decrease in conductive clouds. So, if these conditions are favourable, conductive clouds will increase and India will get more rain. If these are unfavourable, conductive clouds will decrease. In July, it was in favourable condition. Therefore, it supported in increasing conductive clouds and enhancing rainfall. In August, throughout the month, it was the opposite.

We have been noticing that dry regions have started receiving excess rainfall and wet regions less precipitation. What are the factors behind this?

One is climatology, that has large variations in the country itself. If it is 10-20 cm in west Rajasthan, it can go to more than 1500 cm in hills, Northeast and western ghats. India is a big country. Therefore, the variation is large. When we consider year-to-year, in a particular year, monsoon circulation is not fixed. Other than large-scale processes that influence monsoon circulation, there are local weather systems like low-pressure, western disturbances, etc. There will be various push-and-pull or various forces on the regional characteristics of the monsoon. These are called transient systems, which are not permanent. They come and move across, but their characteristics, their frequency, their genesis, their path decide the distribution and intensity of rainfall. Accordingly, rainfall scenario will be different from year to year; it cannot be the same.

Additionally, there are six semi-permanent systems in monsoon regionally, which also influence wind and subsequently rainfall. For example, heating in Pakistan—if it is hotter, monsoonal wind will be stronger. Monsoon is nothing but a land breeze and sea breeze condition. In a particular summer, if it is very hot, winds will blow from ocean to land. It is called sea breeze in the daytime. At night, the land becomes cooler, and the sea is still warm. So, wind blows from land to ocean, and it is called land breeze. Similarly, in India, southwest monsoon wind blows from the ocean to land, which is called giant sea breeze. During the northeast monsoon, it moves from the land to ocean and Siberia will have a high-pressure system. In short, the difference between sea surface heating and ocean surface heating decides the activity of monsoon. Like this, there are six major components of monsoon which are semi-permanent in nature.

The third factor is the weather system developing over the Pacific Ocean. Many South China Sea weather systems come to Bay of Bengal and here, these become low pressure systems and move across Odisha, West Bengal, Gujarat and Rajasthan, and cause a lot of rainfall.

What is being done to improve the forecast?

A number of things are being done. The basic thing for improving forecast is observations. So, we will improve observations (AWS, ARG, Radar, etc.) which is a continuous process. At the same time, our modelling system, modelling process and computing power will improve, and post the process, the product we will get will be utilized to develop new services for various sectors.

Private agencies can work with public agencies in terms of extending IMD’s services, disseminating information, improving capacity and awareness. So, there is a scope in this direction, and we are working with a number of private agencies like Google, M.S. Swaminathan, Reliance, Adani, among many.

Do you think an early warning system is required to avoid the situation we saw in July in northern states, especially in Delhi, Punjab, Haryana, Himachal and Uttarakhand in future?

Forecast is being provided. What do you mean by early? Early has no definite meaning. Early could be one minute early or one year early. Currently, worldwide early warning for large-scale disasters is provided five days in advance. We also follow the same time frame for cyclone and rainfall warning.

Warnings become more accurate as you come closer. Therefore, there is a seamless forecasting system. We go for 15 days forecast and tell that we are expecting wide spell or dry spell, above or below normal rainfall. As you asked, I told you we are expecting below normal rainfall this week and in the coming week, normal precipitation is expected. Thus, I gave a forecast for the fortnight, which is used by planners, agriculture ministry, hydrological ministry, etc.

We provide forecasts for one month, fortnight, seven days, subdivision-wise and district-wise five days, location-specific and NowCast. Therefore, for these different periods, the definition of early varies. As far as warning is concerned, it is five-days warning, colour-coded warning, impact-based warning, evaluated district-level and action taken.

Do you think issuing a forecast more than five days in advance will reduce the impact of severe weather events by taking early action?

India is second to none in cyclone forecast, service delivery, impact forecast, early warning and early action. We provide early warning and ensure that there is an early action. There is a connectivity between early warning and early action. Once there is a low-pressure system, I inform the Prime Minister’s office or cabinet secretary and they call for a meeting and ensure taking early action.

We have introduced a new service called pre-genesis forecast -- forecast before the formation of depression, which is in the stage of low pressure. Before the genesis of depression, usually worldwide, they issue forecast on cyclone, not on depression. Nowadays, the US is issuing forecast on depression. For our ocean basin, which is small, the live period on average is three-five days. So, what will you do giving forecast 15 days prior? We can identify the area where genesis is expected 15 days ahead, but for the intensity forecast, five days are sufficient. Pre-genesis forecast is given seven days ahead now.

We have recently started receiving a warning message from telecom companies amid forecast of an extreme weather event. Has a system been improved to alert people, including farmers who also get impacted?

Dissemination is not the responsibility of IMD; it is a state government responsibility. So, we are coordinating and cooperating with various state governments, so that farmers have specific mobile apps. We are developing API for all information going to various states. The number of farmers is increasing in terms of getting weather-related information. Currently, 30 million farmers are getting the information. We are following a multi-model approach. One is our mobile app Meghdoot for farmers and other apps. Everyone is coordinating through mobile apps across states. Second is Krishan portal of central government agency. Third is mandi—all the mandis are provided weather forecast and agriculture services. The last one is mass media --TV, radio, etc.People start receiving messages in local languages for the first time, indicating common alerting protocol is being implemented which was inaugurated last year by NDMA. In the common alerting protocol, telecom companies are mandated to provide information and through them, it is being pushed. The Delhi government has added it recently.