A plate fin heat exchanger is provided having: a core having a plurality of warm layers for conducting a warm fluid and a plurality of cold layers for conducting a cold fluid, the warm layers making a first pass parallel to at a front face of the exchanger, the front face being first exposed to the cold fluid, and then passing in an essentially counterflow pattern to the flow of the cold fluid through the exchanger from a back of the exchanger to near the front face thereof; and a baffle disposed at the back face of the heat exchanger, the baffle being adapted to create a high pressure profile at the front face such that the cold fluid is distributed upon the front face in such a manner that snow and ice build-up upon the front face is minimized.