Unseasonal rains and hailstorms caused by multiple weather systems, including troughs and cyclonic circulations associated with two consecutive western disturbances (WDs), hit large parts of India in March 2023, causing extensive crop damage. The IMD cited a strong subtropical westerly jet stream and incursion of moisture-laden winds from the Bay of Bengal as reasons for the storm activity. The intense storm activity and rain in India also impacted onion, wheat, and grape production. A climate scientist noted that the warming of the Arabian Sea, which is caused by human activities, could cause more weather system changes in the coming years. More such wind changes are expected to occur during the pre-monsoon season due to the Arabian Sea warming, which may further impact India’s rainfall situation.
The Science Behind Unseasonal Rains and Hailstorms That Flattened Crops in India
Experts have blamed global warming, weak western disturbances, and strong subtropical jet streams for the unseasonal rains and hailstorms that have caused extensive damage to crops in India. Large parts of the country experienced hailstorms in March 2023, accompanied by torrents of rain in the past week. The storms have caused significant damage to standing crops in many states, including Maharashtra, Rajasthan, and Punjab.
The rainfall and storms were caused by multiple western disturbances (WD), other WD-associated weather systems, and many troughs – extended low-pressure areas formed due to the interaction of the WDs and associated systems with winds blowing in from the east, mainly the Bay of Bengal. Experts suggest that a warming Arabian Sea could also be responsible for the intense storm activity and rain.
Between March 5 and March 22, 25 states and four Union Territories suffered from hailstorms, with hailstorms occurring on 14 of the 18 days. Rajasthan, West Bengal, and Maharashtra suffered the most significant crop damage from hailstorms for seven of the 14 days, while Uttarakhand and Himachal Pradesh were hit for six days.
India received 72% less rain than normal between March 1 and March 16, according to data from the India Meteorological Department (IMD). However, this deficit reduced to 60% on March 17, 46% on March 18, and 18% on March 19, while March 20 recorded a slight excess of 5%. The excess rainfall continued to increase until March 22, with 25% excess rainfall recorded on that day, resulting in a significant change in the country’s overall rainfall situation within six days.
In March, six WDs affected India, according to IMD data. The simultaneous activity of multiple weather systems over the country resulted in excessive storm activity throughout India.
The damage caused by the unseasonal rains and hailstorms in Maharashtra is likely to impact the production of onions, wheat, and grapes. IMD data show that, between March 1 and March 16, only one state and one Union Territory received large excess rainfall. By March 23, 18 states had received large excess rainfall, and four states had received excess rainfall.
The Science Behind Unseasonal Rains and Hailstorms in India: Multiple Weather Systems and Greenhouse Gases to Blame
Unseasonal rains and hailstorms that caused extensive crop damage in India during the week of March 16-23 were caused by multiple weather systems, including troughs and cyclonic circulations associated with two consecutive western disturbances (WDs), according to the India Meteorological Department (IMD). The IMD also cited a strong subtropical westerly jet stream and incursion of moisture-laden winds from the Bay of Bengal as reasons for the storm activity. The lowering of the freezing level in the atmosphere helped in the formation of hail.
The first WD was active between March 16 and March 20, and the second was active between March 19 and March 22, while another WD started affecting India from March 23. On March 19, there were eight small and large weather systems active over India, and on March 20, there were six such systems. Unlike weak WDs, which mainly affect northern India, these troughs can destabilize the weather over a large part of India since they have a broad extent.
According to Akshay Deoras, a research scientist at the National Centre for Atmospheric Science and Department of Meteorology, University of Reading, the strong subtropical jet stream over India has been showing undulations since the beginning of March, indicating troughs or elongated regions of relatively low atmospheric pressure. This pattern is similar to what was observed during previous spring seasons, including in March 2015, but it was much weaker.
However, the troughs in March 2023 were able to penetrate India, reaching southern parts of the country, causing enhanced and widespread storm activity. During March 16-17, the atmosphere over several states of India was unstable, which triggered thunderstorms. Cool air brought by a trough in this period helped hails from severe thunderstorms to reach the ground without much melting.
Raghu Murtugudde, a climate scientist at the University of Maryland and Indian Institute of Technology, Bombay, cited the warming of the Arabian Sea as another reason for the storm activity and rains. The warming of the Arabian Sea is a direct result of global warming caused by the emissions of greenhouse gases into the atmosphere from human activities.
The intense storm activity and rain in India in March 2023 resulted in extensive damage to standing crops in many states, including Maharashtra, Rajasthan, and Punjab. The unseasonal rains and hailstorms are likely to impact the production of onions, wheat, and grapes. India received 72% less rain than normal between March 1 and March 16, according to IMD data, with the deficit reducing to 60% on March 17, 46% on March 18, and 18% on March 19. However, the deficit changed to a slight excess of 5% on March 20, increasing to 25% on March 22, resulting in a significant change in the country’s overall rainfall situation within six days.
Arabian Sea Warming to Cause More Weather System Changes
According to a climate scientist, the warming of the Arabian Sea will likely cause more weather system changes in the coming years, with systems steered from the Middle East and backflow creating rain over parts of eastern and peninsular India. He expects more such wind changes to occur during the pre-monsoon season due to the Arabian Sea warming.
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