I began by tweaking the color to a twilight blue and then did a 2nd edit turning it very yellow. Next came the overlay with the blue on the top layer. I then erased the windows so the yellow would show through hoping to give the windows a look that lights were on in the mansion. I'm not completely happy with how that turned out but...oh well :D. Next step was flattening it all and resizing for the web. Next I added snowfall. To do that I created a new file the size of the original image and filled it with black. To simply this detail I will number it. #1 Filter>Noise>Add Noise, 200%, check Gaussian, and monochromatic. #2 Filter>Blur>Gaussian Blur, 2 pixels, #3 Levels, blacks 127, mid range .74, whites 169, #4 Filter>Blur>Motion Blur, Angle -53 degrees, Distance 10 pixels, #5 This next part is a bit tricky. The snow needs to be smaller. Duplicate the snowy layer then select the top layer. I then reduced the size by the Free Transform tool to about 1/4 the size. Double click to set the layer. Now just hold down the alt key while moving this copy and paste it in different areas until the entire snowy layer is covered with the smaller layer. #6 change blending mode to screen. This youtube video explains it better than I can.

http://www.youtube.com/watch?v=A0-4p_65vxQ

Last couple of steps was I selected half the scene with the mansion and copied it. I then deselected it and copied it to the photo. Next flip it horizontally to make a mirror image. Last but not least, when I did that the tree trunk on the left didn't have the snow falling the same direction and the tree trunk has snow on the opposite side so I had to select the tree trunk on the right and carefully paste it to the other side on the left evergreen tree and tweak it with the Free Transform tool.