The back of our house faces North, so doesn’t get much sun. Higher up the roof, the sun melts snow, which runs down and re-freezes in the gutter, blocking it:
My favorite “appetizer” at the Cheesecake Factory restaurant:

… I pass this little shopping square on the way to work every day (“Highwave” is where I get my hair cut) – this view of snow piled up (plowed from the parking lot) is repeated all over the place, at least until the weather is warm enough to get some melting:
