Most parts of country records excess rainfall in March, says IMD

IMD data shows that the record rainfall in March in the country was 62.6 mm in 1967. The rainfall in March this year is ranked 27th while considering data from 1901. Similarly, the rainfall over Central India is ranked 11th in terms of long-term data, with March 1944 recording the highest amount of 48.9 mm.

The pre-monsoon season from March to May is marked by thunderstorms, hailstorms, and squalls, according to IMD Director-General Mrutyunjay Mohapatra. “From March 14 to 21, there was large-scale hailstorm activity across the country,” he said. Himachal Pradesh and Uttarakhand have recorded seven to 11 hailstorm days in March, while Punjab, Haryana, Chandigarh, and Delhi saw one to three days.

The second half of the month of March saw “unusual long spells” of thunderstorm activities over large parts of the country, according to the IMD. The data shows that 100 weather stations reported heavy rainfall in March this year, the highest since 2018. In 2022, only 13 stations reported heavy rainfall in March. “This year, the moisture was quite high due to an anticyclone in the Bay of Bengal, bringing heavy rainfall. Convective activity and moisture content were so high that it brought heavy rainfall. But the number of rain gauge stations has also increased over the years,” Mohapatra said.

What caused this weather? One factor was that seven western disturbances affected north and Central India consecutively in March, with five of these being active, Mohapatra said. Western disturbances are storms that develop over the Red Sea, Caspian Sea or Mediterranean Sea and move eastwards with induced circulations being associated with it. Another factor was a trough or region of low pressure from Rajasthan to eastern India.

The particularly severe weather from March 14 to 22 was also associated with strong westerly jet streams, according to the IMD. Jet streams are weather events in the upper troposphere that are associated with winds from 120 kmph to 200 kmph. Jet streams also result in moist air moving upwards and forming clouds. These jet streams were also associated with hailstorms.

“Hailstorm is precipitation in solid form and for this, the atmosphere needs to be colder. The freezing level is usually at a height of around 4.5 km. The jet stream brought this freezing level down to around 3 km, and water vapour turned to solid form, resulting in hail. The hail was mainly because of the jet stream, resulting in lowering of the freezing level,” Mohapatra explained.

Another factor that brought rainfall was two anticyclonic circulations, one over the Bay of Bengal and another over the Arabian Sea that brought moisture to the country.

The thunderstorms, hail, and winds resulted in a March that was cooler than last year. “In most of the country, the temperature was below normal, except for parts of northeast and northwest India, including the hill areas, Punjab and Haryana,” Mohapatra said, adding that March was a warm month last year, while it was cooler this year.

Last year, the average maximum temperature in March across the country and over northwest India was the highest from 1901. The average maximum temperature over northwest India was 30.73 degrees Celsius in March last year, while it was 27.48 degrees this year.