The high \(p_{\rm T}>3\) GeV azimuthal asymmetry, \(v_2(p_{\rm T})\), in non-central nuclear collisions at RHIC is shown to be a sensitive measure of the initial parton density distribution of the produced quark-gluon plasma. A generalization of the Gyulassy-Levai-Vitev (GLV) non-abelian energy loss formalism including Bjorken 1+1D expansion as well as important kinematic constraints is used.