It is almost always best to call in professional snow removers when dealing with the roof in the winter. It is very dangerous to attempt roofing work when it is icy and snowy. People die each year by doing it themselves. Snow removal professionals use protective equipment that is specially designed for them. Saving a few hundred dollars at the cost of your life is not worth it. If you need to call the professionals to remove the snow, understand that they cannot remove all of it, just the snow that is excessively weighted. For the rest of the winter, you should keep the bottom layer of ice on