The complex flow within the molten metallic pool, during advanced manufacturing and joining processes such as welding and additive manufacturing, directly affects the performance of the final components; through the generation of various microstructures and strain gradients. Understanding of the flow within such melt pools can enhance the predictability of the final microstructures and therefore component performance. In situ synchrotron X ray imaging is employed to observe and map the evolving flow patterns within gas tungsten arc weld pools using the tracking particles. The experimentally observed flow patterns are compared with numerical simulations to gain additional insights on accurate predictability in relevance to the physical driving forces within the flow. The spatio temporal distribution of the flow using the mapped data is analyzed by considering the evolution of driving forces acting throughout the weld pool. The results demonstrate quantitative benchmark flow mapping with confirmation of the overall mechanisms of weld pool flow.