These features look related to the flutings described by Joe Simpson in his book Touching The Void. In the second picture there is a stone at the far end of the snow ridge. I was wondering whether a uniform blanket of snow fell and then the wind removed sections that weren't sheltered. I find it more likely that the snow was being fired in at speed by the wind and built up in sheltered areas. If that's the case then it will be like diffraction round objects. The wind would be being into the space behind the stone but have less energy and so deposit snow.
