I know it has been a long time since I have poster here. Sorry, I have been busy. (That is the best excuse I can come up with at least)
Here are some pictures that I took in March. I had seen this twice, but only got around to taking pictures the second time: (You can click on the pictures to get a larger version.)
We had just gotten a big snow the night before. Earlier the same morning this area had all been covered in snow. But as you can se, some snow had melted. What was unusual was that instead on melting in splotches, it had melted along a straight line.
You can see there is quite a sharp devision between the snow and grass.
I have seen this happen along a wall, but as you can see there is no wall parallel to this line.
You have to look up for the answer to this one. The cross walk had apparently cast the shadow that defined the line in the snow. The shadow moved away, but the line stayed.