The rapid melting of glaciers due to the warming climate has led to increase in water levels of glacial lakes, thereby posing concerns about their stability. The rupture of moraine dams due to excessive pressure of the accumulated meltwater results in widespread destruction downstream. A number of such events leading to GLOFs has occurred in the Solukhumbu region of Nepal where five glacial lakes are present. This study focuses on the Thyanbo glacial lake, which experienced a GLOF on 16th August, 2024. Synthetic Aperture Radar (SAR) data has been utilized from the Sentinel-1 satellite to perform detailed analysis for monitoring the changes in the lake extent and trace the pathways of the floodwater. A comprehensive methodology, combining digital elevation models (DEMs) and backscatter analysis of SAR was employed to delineate the floodwater pathways and estimating the changes in the lake area. A peak lake area of \(0.048 , \text {km}^2\) has been observed and corroborated with the ground truth sources, immediately before the occurrence of the disaster, focusing on the lake’s critical stage prior to the failure of the moraine dam. The results provide significant insights into the vulnerability of the lake systems and accurate identification of floodwater pathways, aiding in disaster preparedness and risk mitigation. This study demonstrates the potential of SAR-based monitoring as a reliable, all-weather tool for early monitoring systems in areas of high altitude which are prone to GLOFs.