IMD predicts warmer winter for North India

This year may see a warm winter in northwest and northeast India, but many parts of peninsular India will see a relatively colder winter, the Indian weather office has said.

This year may see a warm winter in northwest and northeast India, but many parts of peninsular India will see a relatively colder winter, the Indian weather office has said.

Global models are showing a warmer-than-average winter for the northern parts. (HT file photo)

Above normal maximum and minimum temperatures are expected over many parts of northwest India and most parts of northeast India during this winter season (December 2022 to February 2023), the India Meteorological Department said on Thursday. This means the frequency of days with maximum and minimum temperatures about 2 to 4 degree C above normal will be higher during the next 3 months.

Below normal minimum temperatures are likely over many parts of peninsular India and some parts of central India and isolated parts of northwest India, but, overall normal to above normal minimum temperatures are most likely over many parts of northwest India (Punjab, Haryana, Delhi, Uttarakhand, Himachal Pradesh, Jammu and Kashmir, parts of Rajasthan) and most parts northeast India. And above normal maximum temperatures are likely over most parts of the northwest India, east, northeast India and many parts of Central India.

The impact of above normal temperatures over the rabi (winter) crop, particularly wheat, depends on the stage of wheat crop, said M Mohapatra, director general, IMD. “ The combination of the dynamic behaviour of weather and dynamic stages of vegetation in wheat crop will determine the impact.”

A warmer than normal spring affected wheat output across India’s northern plains in 2022.

Interestingly, global models consulted by IMD are showing a warmer than average winter for the northern parts of the country despite La Nina conditions. La Niña refers to the large-scale cooling of the ocean surface temperatures in the central and eastern equatorial Pacific Ocean, coupled with changes in the tropical atmospheric circulation, namely winds, pressure and rainfall. It usually has the opposite impacts on weather and climate as El Niño, which is the warm phase of the so-called El Niño Southern Oscillation (ENSO).

ENSO has a major influence on weather and climate patterns such as heavy rains, floods and drought. In India for example, El Nino is associated with drought or weak monsoon while La Nina is associated with strong monsoon and above average rains and colder winters.

“La Nina is only one of the factors, not the only factor which determines temperatures. In November also La Nina was also there. You expect more cyclonic disturbances during La Nina period but there was only one depression. Madden–Julian oscillation (MJO) was active which subdued cyclonic activity. We use a dynamic modelling system which are influenced interactive large scale global features,” explained Mohapatra.

While it is difficult to ascertain the complex interplay of factors, Mohapatra explained the warmer winter may be due to two reasons. “We can speculate that the western disturbance activity may be subdued leading to less cloudiness and both above normal day and night temperatures. There may be higher penetration of easterly winds which may cause temperatures to rise but not bring enough moisture so as to cause rainfall,” he added. IMD is expecting development of two low pressure areas (which may intensify further) in the first and second week of December.

Monthly rainfall for December over south peninsular India, comprising five meteorological subdivisions (Tamil Nadu, Puducherry, Karaikal, Coastal Andhra Pradesh, Yanam, Rayalaseema, Kerala, Mahe and South Interior Karnataka) is most likely to be normal (69-131% of Long Period Average (LPA)). Monthly rainfall over the country as a whole during December is most likely to be below normal (< 71 % of Long Period Average (LPA)).

Below-normal rainfall is most likely over most parts of the country except some areas of south peninsular India and some pockets of extreme northwest India where normal to above normal rainfall is likely. Currently, the Sea Surface Temperatures (SSTs) and the atmospheric conditions over the equatorial Pacific Ocean indicate La Niña conditions. The latest forecasts from Monsoon Mission Coupled Forecasting System (MMCFS) and other global models suggest that La Niña conditions are likely to continue during the upcoming winter season.

The minimum temperatures over most parts of northwest India was above normal in November too. “Yes minimum temperatures were above normal over most parts of northwest India by 1 to 2 degree C. This was mainly because of less influence of western disturbances. There were 5 western disturbances but 3 of them moved to the north of Indian latitude and did not help us. The maximum temperatures were normal to near normal about 1 degree C here and there,” Mohapatra said.