In total, 13 Indian states and 1 Union territory saw heatwaves since March 3, with West Bengal recording the highest
Places across India experienced heatwaves in the months of March and April in 2023 These heatwaves may become more intense as India moves towards the peak summer season in May and the onset of the monsoon season in June.
This would mainly be due to the development of an El Niño event in the equatorial Pacific Ocean.
Since March 3, 13 states and one Union territory of Chandigarh have undergone heatwaves, according to data from the India Meteorological Department (IMD) collated by Down To Earth.
The maximum number of heat wave days were experienced by West Bengal (nine), followed by Andhra Pradesh and Bihar at seven each. Odisha suffered from heatwaves on five days, while Maharashtra and Karnataka on four days each. This data is as of April 20.
The first spell of heatwaves this year began earlier than last year. They started off in coastal Karnataka on March 3, while in 2022 the heatwaves had started in Gujarat on March 11. It ended on March 12 and affected the western coastal regions of Maharashtra, Gujarat, Goa and Karnataka.
After that there were widespread thunderstorms, hailstorms and rainfall across the country, which brought down the day temperatures significantly, leading to a cooler-than-normal March in many areas, especially in northwest India. This had happened due to a series of western disturbances, which interacted with winds blowing from the east, mainly the Bay of Bengal.
The second spell of heatwaves began on April 12 from the eastern state of West Bengal and are ongoing. The reason for this shift of affected regions is the heating up of the northernIndian Ocean. But northwest India may also get hot very soon.
There is a more than 60 per cent likelihood of the development of El Niño in May-June-July, which increases to almost 75 percent for June-July-August, according to the latest El Nino-Southern Oscillation (ENSO) update from the National Oceanic and Atmospheric Administration of the United States.
El Niño, which is the warmer-than-normal phase of the ENSO phenomenon, generally causes more intense heatwaves in India, as it did in 2015 and 2016.
“Surface winds had been organised into anticyclones over the Arabian Sea and the Bay of Bengal, which warmed the North Indian Ocean, especially the Arabian Sea,” said Raghu Murtugudde, a climate scientist at the University of Maryland and Indian Institute of Technology Bombay.
“Now the mid-level westerly jet is in place and is beginning to generate surface winds, which are pumping the ocean heat into the northeastern corner of the Bay but the western / northwestern India is also getting hotter. We will continue to have heatwaves,” he added.
Due to the warm oceans, a cyclone could also be in the offing but the El Niño may counteract its likelihood. “Warmer oceans should favour enhanced cyclogenesis but El Niño tends to bring fewer cyclones. So we have to watch carefully,” said Murtugudde.
“A warmer Arabian Sea during spring should factor a stronger monsoon and may end up compensating a little against the El Niño effects. But extremes in rainfall and their large-scale aggregation are not going away,” Murtugudde concluded.
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