I hear these words about once a year, and they never cease to cause me extreme anxiety. Our house is a Gambrel, meaning two stories in the front, but three in the back as we have a walk-out basement. So there is no way to rake the back roof from the ground.
Raking roofs is serious business. Not only can you get the dreaded ice dams with accompanying leaks -- if you have a flat or low slope roof -- it can collapse from the weight of the snow. Typically this is more common in commercial buildings, but it can happen to houses too. So tonight while I'm praying and typing, I can hear the rake, as see the snow falling out my office window.
Yesterday, my neighbor had a guy with a shovel on her roof - but her house is a ranch - 1 story. Right now I'm wishing our house was only one story.