This study documents the lifecycle and large-scale environment of a large-hail producing supercell that occurred in southern Brazil (SB) on 6 October 2015. The supercell underwent a merger with a nascent supercell near a Doppler weather radar and rapidly intensified shortly after the interaction. The original (premerger) supercell developed in a high-shear, high-instability pre-cyclogenesis environment and remained isolated un...