A first stage turbine stator vane used in an industrial gas turbine engine, the vane having an outer endwall and an inner endwall with the airfoil extending between the two endwalls. A showerhead arrangement of film cooling holes is located along the leading edge region, and a row of exit cooling air slots is located along the trailing edge of the airfoil. A slanted rib extends from the outer endwall to the inner endwall and separates the vane into a forward cavity and an aft cavity. A leading edge impingement tube is secured within the forward cavity to provide impingement cooling to the leading edge walls of the airfoil. The leading edge impingement tube includes a cooling air inlet section extending out from the inner endwall so that a vena contractor forms in the tube entrance before the impingement holes begin. The leading edge impingement tube narrows in the cooling air flow direction. The trailing edge impingement tube has similar construction but has the cooling air inlet extending out from the outer endwall. With this design, the first stage vane can use both impingement cooling of the leading edge region and showerhead film cooling of the leading edge airfoil surface to allow for a higher gas flow temperature across the vane.