Weather gone rogue: Western Disturbances disrupt India's climate and agricultural timetable
The heat stress of the last four months has adversely affected the Western Disturbances, which have direct and indirect economic consequences, a new analysis says.
In the summer months, Western Disturbances (WD) usually tend to travel in higher latitudes, confining snow and rainfall activities to the higher reaches of the region. However, this year, back-to-back WD have led to heavy rainfall spells across hill states, while keeping prolonged heat waves at bay in the northwestern plains.
These disturbances originate from the Mediterranean region and impact India’s climate, primarily in the winter season. They bring rainfall and snowfall (vital for the Rabi crop season) especially in northwestern India, including Punjab, Haryana, and Delhi.
They are characterised by low-pressure systems that move eastward, gaining moisture from regions like Iran and Afghanistan before releasing precipitation upon reaching the Himalayas. Their influence extends beyond winter, affecting agricultural productivity, river flows, and even the onset of the monsoon season, making them critical for India’s agricultural and water resources.
The changes brought about by climate change mean that the subtropical westerly jet (a high-altitude westerly wind current that flows from west to east in the subtropical regions of the Earth) has widened. This could result in a direct impact on the onset and withdrawal of the monsoon. A split in the track of the WD can result in more rain and snow over the foothills of the Himalayas.
Heavy rains and thunderstorms, flash floods and landslides in several parts of Jammu and Kashmir last week, as well as heavy rain in parts of Himachal Pradesh and Uttarakhand, which triggered flash flooding and landslides is caused by back-to-back WD.
The arrival of these systems at a regular interval has kept prolonged heat waves away from the northwestern plains so far, though heatwaves have made on and off appearances. The heat directly impacts many crops—including mangoes, which need the heat in order to ripen.
As the traditional dynamics of WD change, the year-round moisture feed is making the Himalayas increasingly vulnerable to extreme weather events like flash floods and heavy snowfall. This will lead to the blurring of seasonal boundaries and a restructuring of atmospheric behavior, signalling a re-engineering of India’s weather systems.
India