Northwest India recorded its hottest June since 1901: IMD
The weather department flagged as unprecedented the 235.5mm rainfall recorded in a 24-hour window on June 28 — the highest since 1936
It was the warmest June for northwest India since record keeping began in 1901, the India Meteorological Department (IMD) said on Monday, bearing out the deadly heat spell recorded over Delhi, Uttar Pradesh and other parts of the region which killed at least 100 people.
The weather department flagged as unprecedented the 235.5mm rainfall recorded in a 24-hour window on June 28 — the highest since 1936 — and said that correct forecasting of the event was a challenge because nearly 100mm rainfall was recorded in parts of the city within an hour.
June ended with 11% deficiency in monsoon rain for the country, 7th lowest rain since 2001, making it a month of it a month of extremes.
For July, IMD expects extreme rain and flooding over parts of the country especially in the foothills of Western Himalayas.
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IMD has forecast very active monsoon over the country in July at 106% of Long Period Average. There is likely to be normal to above normal rain over most parts of the country except many parts of northeast India, some parts of northwest, east and peninsular India where below normal rainfall is expected.
Warmest June for northwest India
At 31.73°C, the mean temperature over northwest India was 1.65°C above normal. The average maximum temperature over the region was 38.2°C, nearly 2°C above normal, and even the minimum temperature was the second highest since 1901 at 25.44°C, 1.35°C above normal.
East and northeast India also recorded its warmest June in terms of night time temperatures recording an average minimum temperature of 25.14°C, nearly 1°C above normal.
Compared to a normal of three to four heatwave days, parts of Indo-Gangetic plains, northwest India, central and north India recorded a range of 10 to 18 heatwave days in June.
Uttar Pradesh recorded 18 heat wave days, Bihar 13, Gangetic West Bengal 9, Delhi and Haryana region recorded 14, Punjab 11, and Himachal Pradesh 10 days among others.
Between April and June, 20 to 38 days of heatwave were recorded in different parts of east, north and central India. Most frequent heatwave (20-38 days) were recorded over Rajasthan, MP, Punjab, Haryana, Chandigarh, Delhi, West and East UP and HP, Odisha, West Bengal, Jharkhand, Bihar, Saurashtra and Kutch, according to IMD.
Extreme localised rain over Delhi
On July 27, IMD forecast “heavy” rainfall over the plains of northwest India but what happened over Delhi was “impossible” to predict, said M Mohapatra, director general, IMD.
“There are some situations that seem just impossible. Our data shows some stations recorded up to 91 mm rain between 5am and 6am. This extreme rainfall event was very confined spatially and temporally over some parts of the city, Safdarjung area for example. So, definitely it is a challenge but we are trying to address it,” said Mohapatra, adding that three more radars will be added to the existing three for better forecasting of extreme rain; automatic rain gauges will be added and urban flood forewarning system will be deployed.
Overall, however, it was a mesoscale event mainly due to monsoon advancement, he said.
“Our heatwave warning performance has improved by about 10 to 20% since 2019. But when there is continuous extremely warm atmospheric conditions for several days, the moisture holding capacity of the atmosphere increases and so immediately after that rain can be unprecedented. That is how climate change impacts. With every degree of warming, the moisture holding capacity of the atmosphere increases by 7%,” explained Mohapatra.
Heavy rain possibility in July
Monthly rainfall over the country as a whole during July 2024 is most likely to be above normal (>106 % of LPA). The LPA of rainfall over the country as a whole during July based on data from 1971-2020 is about 280.4 mm. During July, normal to above normal rainfall is most likely over most parts of the country except many parts of northeast India and some parts of northwest, east and southeast peninsular India where below normal rainfall is likely.
In July, minimum temperatures are most likely to be above-normal over many parts of the country except some parts of northwest and adjoining areas of central India and some pockets of south-eastern peninsular India where normal to below normal minimum temperatures are likely. “When its cloudy, warmer than normal nights are expected,” said Mohapatra.
The maximum temperature is likely to be normal to below normal over many parts of the Northwest India and south peninsular India except West coast. Above normal maximum temperatures are likely over many parts of central India, east and northeast India and along west coast.
“There is higher probability of rainfall and flooding over the foothills of Western Himalayas and central India. But we as an agency do not provide flood forecast,” added Mohapatra.
Currently, El Nino-Southern Oscillation (ENSO) neutral conditions are observed over the equatorial Pacific. The sea surface temperatures (SSTs) are above average in the equatorial western and central Pacific Ocean, and below-average over the eastern equatorial Pacific Ocean. The latest Monsoon Mission Climate Forecast System (MMCFS) indicates that the La Nina conditions are likely to develop during second half of the monsoon season.