Examining the Changes in Precipitation Patterns Across the Western Himalayan Region During the Winter Season

The Himalayas are associated with ever-challenging topography and changing dynamic climatic conditions. The climatological winter precipitation was studied over the Western Himalayan region (WHR) during two time periods spanning 30 years each (1961–1990 and 1993–2022) using ERA5 reanalysis. Analysis illustrates that the decline of the large-scale precipitation is much more prominent than convective precipitation over the WHR. Although large-scale precipitation decreases, a greater fraction of it falls as rain rather than snow, partially offsetting the reduction in snowfall. The study reveals that the atmospheric dynamics favours the influx of moisture into the study domain; however, the combination of the rising temperatures, which increase the water-holding capacity of the atmosphere, and the decreasing strength of vertical winds reduces the updraft, resulting in a greater decline in precipitation in recent times. Further, the decreased transport of moisture into the upper troposphere leads to a decline in the cloud micro-physical parameters that support large-scale precipitation. The study also revealed that, although the number of western disturbances (WDs) and WD days are on the rise, their track density passing through the WHR has declined due to a northward shift, resulting in a decrease in the large-scale precipitation. These findings indicate potential shifts in precipitation types and patterns, which could have significant climatic implications for the regional hydrological cycle.