Shock/boundary layer interaction alters the near field mean flow of a transverse jet in supersonic crossflow by bifurcating the phase portrait of the separation topology through the addition of saddle points, nodes and separation lines. Moreover, the interaction generates additional flow structure in the near field that affects the surface pressures and ultimately the jet interaction performance coefficients. This study examines the flow structure, separation topology and performance characteristics of an underexpanded transverse jet issuing normally into subsonic and supersonic freestreams. New flow structure in the near field of the jet has been identified adding to the basic understanding of jet interaction.