From Snow to Storm: Western disturbances no longer just a winter story

IIT Roorkee research suggests that western disturbances are no longer impacting only the country's winter cycle but are also significantly influencing the pre-monsoon period and the onset of summer.

A new study by researchers at an Indian Institute of Technology has found that western disturbances, a key weather system affecting northern India, are changing in both timing and intensity. The findings have raised concerns about climate resilience, disaster preparedness and water security in the Himalayan region.

Western disturbances are low-pressure systems that originate in the Mediterranean region and travel eastwards. They bring winter rain to north India and snowfall to the Himalayas. For decades, they have been linked mainly to the winter season, playing an important role in replenishing glaciers and supporting agriculture.

However, the new research shows that these systems are now becoming more active beyond winter, especially during the pre-monsoon months of March to May. The study, published in the International Journal of Climatology, suggests that climate warming is not only increasing extreme weather events but also altering the structure and seasonal role of large atmospheric systems.

Researchers analysed over 70 years of atmospheric and rainfall data. They found that western disturbances are now travelling longer distances and absorbing more moisture before reaching the Indian subcontinent.

Upper-level winds associated with these systems have also strengthened. Together, these changes are leading to heavier rainfall outside the traditional winter period.

Spandita Mitra, a PhD scholar in the Department of Hydrology involved in the study, said long-term climate data is essential to track these shifts. She noted that erratic rainfall and sudden extreme events seen in recent years reflect these broader atmospheric changes.