How rising heat and shifting WDs are fuelling extreme weather, ‘blurring of seasonal boundaries’

Heavy rains, thunderstorms, flash floods and landslides in several parts of Jammu and Kashmir last week led to widespread damage and loss of lives. Parts of Himachal Pradesh and Uttarakhand also recorded heavy rains earlier this month.

Meteorologists say back-to-back Western Disturbances that caused the heavy spells in hill states while keeping prolonged heat waves away from the plains of Northwest India all point to a significant shift in behaviour. 

“The traditional dynamics of WDs are undergoing a profound shift due to climate change,” they add.

The rise in the frequency of WDs has made Himalayan states more vulnerable to extreme weather events. There has also been a shift in precipitation seasonality, with peak snowfall moving from February to March by the end of the 21st century, according to experts.

“Increased frequency of WDs affected the flow of dry and hot northwesterly winds. Warmer winds were replaced with comparatively cooler easterly winds, bringing temperatures down. Parts of Central and West India also have not seen prolonged heat wave spells in the season so far,” says Mahesh Palawat of the Skymet Weather.

Climate change and WD; frequency

The signs of climate change are all visible.

According to former IMD Director General Meteorology KJ Ramesh, WDs picked up frequency from late January onwards and since have been affecting Western Himalayas at regular intervals. Their influence is growing significantly over J&K, Himachal Pradesh and Uttarakhand—where they have been dumping more rainfall.

Quoting the latest research, experts say higher elevations are very likely to receive significantly more precipitation in a warmer climate with insignificant drying in the foothills and increased rainfall over the plains of north India and Pakistan.

Storms that predominantly affect North India and Pakistan during winters, WDs are weather systems embedded within the subtropical westerly jet that lies over the Indian region.

They travel across the year, but in different latitudes.

In winter, they travel in lower latitudes, bringing significant amounts of rain and snow over North India.

In summer, they normally travel in higher latitudes, confining snow and rainfall activities to the higher reaches of the region.

WDs—their importance

Accounting for nearly 15% of annual precipitation, WDs have a vast impact over economic and agricultural outcomes.

During winter they provide rain to the agricultural tracts, the snow they bring sustains reservoirs, providing irrigation for rabi crops. This water helps bridge the dry pre-monsoon months of May and June while late-season WDs impact the kharif crops.

They are also essential for maintaining glacier mass balance in a region noted for its unusual glacial stability.

But amid global warming scientists are warning against “increasing erratic trend”.

Ramesh explains that global warming has led to rapid warming of the Arabian Sea, which then emits more moisture northwards.

“Now, when the amplitude of WD extends up to the North Arabian Sea, more moisture is fed into the system, resulting in intense weather activity over the hills.

“If we see, snow water equivalent anomaly, there is the presence of unusual snowfall. In a large sense, their weather patterns this year show a different trend.”

Snow water equivalent is the depth of water that would cover the ground if the snow cover was in a liquid state.

What to expect

According to Prof AP Dimri, Director, Indian Institute of Geomagnetism, increasing heat stress has altered characteristics of WDs and will continue to do so if global temperatures continue to rise.

“There is growing evidence that WDs are impacting weather outside the winter season, leading to extreme precipitation events. There is no doubt that increasing heat stress is the basis of everything, as it is generating more energy and at the same time pushing moisture upwards,” he adds.

The subtropical westerly jet (SWJ) has widened because of climate change, providing a wider area to WDs to travel in different directions.

“WDs will now have more meridional oscillations, meaning that they can now travel to the north boundary as well as to the south boundary of the jet. Earlier, there was not enough space for such oscillation in comparison to the present situation. They are also getting uplifted and are now reaching up to Karakoram range bringing more snowfall there,” says Dimri.

Fears are that climate change will cause winter precipitation to increase over the western Himalayas but to decrease in the foothills.

Climate change may also cause the ratio of snowfall to rainfall across the region in winter to decrease.

“Snowfall will tend to decline at the expense of increasing rainfall across the foothills but will tend to increase over the Karakoram and Tibetan Plateau. Glaciated regions like much of the Karakoram are projected to witness increase in snowfall,” they say.

With more space available for oscillation, WDs are also now able to split their track.

“The traditional dynamics of WDs are undergoing a profound shift due to climate change. This year-round moisture feed is making the Himalayas increasingly vulnerable to extreme weather events like flash floods and heavy snowfall.

“What we’re witnessing is the blurring of seasonal boundaries and a restructuring of atmospheric behaviour. These aren’t isolated anomalies — they’re signals of a changing climate that is re-engineering India’s weather systems. Policymakers, disaster authorities, and communities must adapt swiftly to this new normal,” says Prof Anjal Prakash from Bharti Institute of Public Policy.

India