I know it looks like someone drew this on my window; but, I swear it is authetic.. It formed on the outside screen on my upstairs hall window. Last year we had one form on the Kitchen window. It's weird but it's true.
It's from your secret admirer!
(lol) That's a thought. Of course, the window is on the second floor and the yard has about four feet of snow in it. Anything is possible though.
I live in Houghton County in the Upper Peninsula of Michigan.
The white, two story Colonial, 3rd house on the right with the ladder lying in the side yard.