Observed Trends in the South Asian Monsoon Low‐Pressure Systems and Rainfall Extremes Since the Late 1970s

Abstract The core Indian monsoon region receives more than half of the rainfall extremes from low‐pressure systems (LPSs), which typically form over the Bay of Bengal and propagate upstream against the time‐mean low‐level westerlies. Yet, the relationship between the trends of LPSs and rainfall extremes remains uncertain. Using two tracking algorithms and reanalyses‐derived LPSs, we find that LPS activity and extreme rainfall exhibit coherent trends during the post‐1979 satellite era. Over time, the LPSs propagate preferentially into south‐central India rather than north‐central India, imparting a corresponding dipole footprint in rainfall extremes. Consistent with existing theories that the diabatic heating is instrumental in shifting the LPSs west‐southwestward, the LPSs traveling through south‐central India have stronger updrafts on their west‐southwestern flank than those passing through north‐central India. The increased frequency of LPSs propagating into south‐central India is likely due to a strengthened cross‐equatorial moisture transport, which favors stronger storm ascents.