Mid-Latitude Dynamical Changes Explain Persistent Glacier Stability in the Karakoram

Western Disturbances (WDs) are upper-tropospheric synoptic-scale systems embedded in the subtropical westerly jet stream, playing a critical role in winter precipitation across the north and northwest Indian subcontinent, including the Himalayas. This study synthesizes insights from multi-decadal analyses (1980–2019) using reanalysis datasets (ERA5, MERRA-2, NCEP-CFSR/CFSv2) to characterize the evolving dynamics, precipitation patterns, and regional impacts of WDs. In the core WD zone of north India, although WD frequency remains relatively stable, a sharp decline (~49%) in intense (strong and extreme) WDs and associated precipitation suggests an increasingly inhibitive dynamic environment with reduced moisture advection. Conversely, over the Karakoram region, WDs have intensified in recent decades, exhibiting a ~10% rise in precipitation intensity and contributing up to ~65% of the total seasonal snowfall. This enhanced snowfall sustains the so-called “Karakoram Anomaly”, a regional glacier stability or mass gain contrasting widespread glacial retreat elsewhere in the Himalayas. The anomaly correlates with declining non-WD snowfall (~17%) and increased baroclinic instability, along with a notable eastward shift (~9.7°E) in the genesis zone of Karakoram WDs toward regions with higher cyclogenesis potential, convergence, and moisture availability. Furthermore, a slowdown in WD propagation speeds has led to more intense and prolonged precipitation events in the region. Collectively, these findings highlight the divergent regional impacts of WDs across the western Himalayas and underscore their central role in driving winter hydroclimate variability, glacier dynamics, and climate change responses in one of the most climate-sensitive regions on Earth.