"The heat inside the house rises and causes the snow and ice to melt so there's an under layer you can't see of a couple inches of water."
Barry says the biggest issue is many drains are frozen solid and the water has nowhere to go.
So here's what you need to do:
"Shovel gently and clean the area around the drain box."
Use plastic shovels since they won't puncture or cause any damage to your roof.
"Put some hot water down there that loosens it up real quick and then put some salt."
That'll keep your drain box from re-freezing. But salt only around your drain box, salting your entire roof can degrade the coating. And think safety first don't get too close to the edge and go slowly so you don't slip.
Other tips:
-Do not use heavy equipment like snow blowers unless you're sure your roof is strong enough to handle that load
-If you have a flat roof or live in a row home look at your ceilings for new signs of stress like cracking, splitting, or sagging
-Evacuate immediately if you have any suspicions your roof may be over stressed
