I found this really difficult as the snow kept melting and sliding down the window. This would have been ok except I was using a macro lens and 3 extension tubes and a time delay on the camera.
It doesn't take that long to lose a snowflake....... :o(
I believe there are more on the way though. ;o)
I tried this before and this is marginally better as there is actually a snowflake. Next time I might get it right.
Scavenger hunt item #34 - Snowflake