We spent 6 years living in Minnesota before we moved to North Carolina and warmer climes. I will admit that I never got completely used to the cold winters there, but we did have some great times, especially when the Rowen got old enough to play outside in the snow for a little while.
To create the overlay, I used the Bamboo to trace several snowflake patterns, filled some of the shapes with color, and then used the Magic Wand tool to extract the color and place it on its own layer behind the white overlay. I offset the colored shapes just a bit, to give it a bit of an overprinted feel.