I will describe joint work with Jared Wunsch on propagation of singularities for some semiclassical Schrodinger equations where the potential has singularities normal to an interface. Semiclassical singularities of a given strength propagate across the interface, but only up to a threshold. This is due to diffracted singularities which are weaker than the incident singularity by a factor depending on the regularity of the potential. Time permitting, I will give applications to logarithmic resonance-free regions in scattering theory.