Convectively Coupled Kelvin Waves and Extreme Rainfall in Northern South America

Convectively Coupled Kelvin Waves (CCKWs) play a key role in synoptic variability and can trigger extreme hydrometeorological events. This study characterizes the influence of CCKWs on seasonal precipitation patterns and extreme precipitation events (EPEs) over northern South America. Using a filtered OLR dataset, we found that precipitation anomalies associated with CCKWs are sensitive to the selected index region. A sensitivity analysis identified a region in the Colombian Pacific exhibiting the strongest precipitation anomalies linked to CCKWs. At seasonal scales, March–May (MAM) is the season with the highest CCKW activity, and its convective phase is associated with enhanced precipitation over the far eastern Pacific, western Amazonia, and northern Colombia, while suppressed convection dominates northwestern Brazil. In addition, three regions exhibit increases of up to 30% in EPE occurrence during convective-phase Kelvin waves: (i) the northwestern Amazon, (ii) northwestern Colombia, and (iii) the Peruvian coast. In contrast, EPE occurrence in the Colombian Pacific appears largely independent of CCKW passage, likely due to the strong background climatological rainfall in the region. We also analyze a flooding event in Turbo, Colombia, on 9 May 2007, that occurred during the passage of a convective-phase Kelvin wave and was preceded by days of enhanced low-level southwesterly flow convergence and persistent rainfall. Understanding the influence of these intraseasonal oscillations on precipitation and EPEs is essential for improving regional weather forecasts and supporting the development of early warning systems.