How to Fix a Roof Leak in the Winter?

Ouch. The first thing you need to do is contact your insurance company! Ice and snow in the gutters shouldn't be causing this problem. The leak is coming from the roof itself. I would contact a professional and have them come out to assess it. Another source of the leak may be from poorly sealed windows in your basement. They will need to be recaulked or replaced. I strongly urge you to get the opinion of a professional. Any time there is moisture like this you run the risk of damaged studs, too.

It sounds like ice and snow is melting up behind your shingles. Until you get this ice and snow off, nobody can fix this roof. If the roof still leaks, you could temporarily patch it with black roofing tar. I'm not sure what a person would do in your situation afterwards; though, I wonder if your roof pitch isn't steep enough for your climate. In your situation I'd be thinking about a rubber roof, those things are pretty much watertight. I'd top it with lawn. :)