Seasonal Shifts and Structural Changes in Western Disturbances Over Hindu Kush Himalayas

ABSTRACT Western Disturbances (WD) are eastward‐moving extratropical cyclonic systems recognised as key contributor to winter precipitation (December–February) over northern India, Pakistan, and the Western Himalayas. Recently, their activity has been increasingly observed during the pre‐monsoon (March–May), yet systematic analyses of this shift remain sparse. The study evaluates behavioural and structural changes in WDs across two distinct periods (1950–1976 and 1977–2022). Here, the vorticity‐based WD track data coupled with the ERA5 reanalysis dataset has been used. Behavioural changes are investigated through frequency trends, maximum vorticity distributions, and mean track evolution, while structural shifts are examined using composite vertical profiles of key atmospheric variables. Our results reveal a notable increase in WD frequency during the pre‐monsoon season in recent decades, along with enhanced maximum vorticity and a westward shift in WD origins and longer track durations, enhancing moisture transport potential. Structural analyses further demonstrate significant strengthening of upper‐level zonal winds, intensified mid‐tropospheric convection and atmospheric moisture availability. Such transformations indicate a transition of WD towards hybrid systems with enhanced convective features, raising the likelihood of extreme precipitation events during pre‐monsoon. This improved understanding of the evolving WD dynamics is critical for hydrological planning, climate action, strategies, and disaster preparedness in the highly vulnerable Himalayan and adjoining regions.