The circular movement of synchronous extreme precipitation preceding Kerala floods in 2018 and 2019.

This article investigates the extreme precipitation (EP) events that caused devastating floods in Kerala, India, during the Indian Summer Monsoon (ISM) of 2018 and 2019, using a complex systems theory approach. By constructing time-varying functional climate networks based on event synchronization (ES) of precipitation, outgoing longwave radiation (OLR), and integrated vapor transport (IVT), the study reveals a large-scale, self-organized pattern of synchronized extreme rainfall originating in the equatorial Indian Ocean, propagating eastward across the Bay of Bengal and Maritime Continent, and then moving westward to accumulate over southwest India. The findings indicate that enhanced convective activity and atmospheric moisture transport were key drivers of these EP events, which unfolded over intraseasonal timescales and spatial scales of 100–1000 km. This network-based analysis offers improved understanding of the spatiotemporal dynamics of monsoon-related extreme rainfall and holds potential for developing early warning systems for such catastrophic floods.