A turbine rotor blade is provided for a turbine section of an engine. The turbine rotor blade includes a platform and an airfoil extending from the platform into a mainstream gas path of the turbine section. The airfoil includes a first side wall; a second side wall joined to the first side wall at a leading edge and a trailing edge; a tip cap extending between the first side wall and the second side wall; a first parapet wall extending from the first side wall; and a first cooling hole through the tip cap and the first parapet wall configured to deliver cooling air. The first cooling hole has a closed channel section and an open channel section. The open channel section forms a slot.