IMD forecasts El Nino formation in July; says India may get normal rainfall in the month

India may get normal rainfall in the month of July, despite the development of an El Nino phenomenon in the equatorial Pacific Ocean, according to the India Meteorological Department (IMD).

The IMD has forecast the formation of the El Nino phenomenon in the equatorial Pacific Ocean in July. El Nino is the warm phase of the El Nino Southern Oscillation phenomenon and causes major disruptions of weather conditions worldwide, especially heightened temperatures and decrease or excess of rainfall.

It also said the Ocean Nino Index — which is the measure of the anomalies in the sea surface temperatures in the equatorial Pacific Ocean averaged over a period of three months — is borderline El Nino (0.47) at the end of June. This would go past the threshold (0.50) in July to reach a value of 0.81, the IMD added.

El Nino generally decreases monsoon rainfall over India and has already been declared by other weather agencies such as the National Oceanic and Atmospheric Administration (NOAA) of the United States.

NOAA declared the existence of the El Nino in the equatorial Pacific Ocean on June 8. The World Meteorological Organization will come up with the El Nino outlook in the first week of July.

This is after the month of June was characterised by a litany of extreme weather events, including heatwaves, extremely severe cyclone Biparjoy, floods in Northeast India and landslides in Himachal Pradesh. There was also the weird progress of the monsoon winds over the country with more than 10 days of stalling, followed by rapid progress.

The IMD is expecting normal to above normal rainfall in most parts of central India and adjoining south peninsular and east India and some areas of northeast and northwest India. Eastern and central India have experienced deficient rainfall in June, along with heatwaves.

The rainfall in central India and some parts of northwest India in the first week of July would be aided by the formation of a low pressure area in the Bay of Bengal around July 4.

Two such low pressure areas helped the monsoon’s progress and performance in June as well. The first of these formed on June 9 and moved towards the northeastern states, causing heavy rainfall and subsequent flood-like situations, especially in Assam.

The second low pressure area formed on June 25 and helped the progress of the monsoon winds across the eastern and central states up till northwest India.

“The rainfall in the month of June was deficit by 10 per cent but it has been observed that in the years when June rainfall is below normal July rainfall has been normal,” said Mrutyunjay Mohapatra, director-general of IMD in a press conference on June 30, 2023.

The country-wide deficit of 10 per cent does not paint the entire picture as till June 29, 53 per cent of the districts had received deficient or large deficient rainfall. Among states, 14 had deficient rainfall and two had large deficient rainfall.

There was a huge deficit of rainfall along the western coast of India, especially in Kerala which received 60 per cent less rains than normal in June (till June 29).

“In the third week of June there were heatwaves in eastern and central India, heavy rainfall and floods in northeast India and the rainfall from cyclone Biparjoy in western and northwestern India,” said Mohapatra.

There were 377 very heavy rainfall events (between 115.6 mm to 204.5 mm) across the country and 62 extreme heavy rainfall events (more than 204.5 mm) in the month of June, according to IMD.

The number of very heavy rainfall events was the highest in the past five years and more than double of what occurred in 2022.

Most of the extreme rainfall events were concentrated in Gujarat and Rajasthan in western India and Assam and Meghalaya in northeast India.

The ones in the west were mostly due to the rainfall activity from the cyclone Biparjoy and the ones in the northeast were due to the low pressure area and active monsoon conditions.

The cyclone caused significant heavy rainfall in Gujarat, Rajasthan, Madhya Pradesh and adjoining Uttar Pradesh, leaving the first two with huge excesses in rainfall for June.

As of June 29, Rajasthan had received 188 per cent more rainfall than normal, while Gujarat had received 78 per cent excess rainfall.

“The genesis of cyclone Biparjoy helped with the onset of the monsoon over Kerala on June 8. But its activity afterwards stalled the monsoon over the Arabian Sea and subsequently over the northern part of peninsular India,” said Mohapatra. He added that cyclone Biparjoy was one of the longest-lived cyclones in recent times.

The monsoon winds over the Bay of Bengal stalled between June 12 and June 21, while over the Arabian Sea they stalled between June 11 and June 23.

The stalling of the Bay of Bengal branch of the monsoon system caused above normal heatwave days in many eastern, central and some southern Indian subdivisions.

The maximum number were observed in Bihar at 19 and the second highest in Gangetic West Bengal at 17. Fourteen heatwave days were observed in Jharkhand, Odisha, Telangana and coastal Andhra Pradesh which was the second-highest. The heatwave days were above normal in West Bengal, Odisha, coastal Andhra Pradesh, Bihar, Jharkhand and Chhattisgarh.

A total of 218 met-subdivision-days (MSD) have been observed between March to June all across India, which is the third-highest in the last 13 years. The highest was in 2010 at 578 and the second highest in 2022 at 455 MSDs. When one meteorological subdivision reports a heatwave for one day, IMD defines it as one met-subdivision-day.

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