A fan shroud for a cooling fan assembly with a fan that is rotatable about an axis of rotation defines a downstream direction along the axis of rotation. The shroud includes a barrel for containing the fan. The barrel is concentric with the axis of rotation and further includes a base portion. A plenum includes a plenum body extending radially from the base portion. The plenum body defines at least one edge of length L1. A skirt extends proximate the at least one edge of length L1 and substantially parallel to the axis of rotation. An interface joins the at least one edge of length L1 and the skirt and has a length L1. The interface comprises an underside having a transition surface of a length less than length L1.