I'd vaguely heard of these home-maintenance things called snow roof rakes, but didn't really know why one would need one.
Well, now I know. It's so you don't have a little rain shower in your living room, thereby necessitating an afternoon outside in the rain, atop a ladder, swinging an ice axe.
Apparently the snow on the roof can melt and freeze into an ice dam. This ice dam will of course grow into the gutters, and if it's large enough it will cut off the exits for melted snow behind it. Water pools on the roof under the snow and ice, and eventually finds its way inside.
Our trouble spot (yes, this happened once before, but I managed to push it out of my mind) is the triple window in our family room. The water must be dripping down inside the walls, and it collects in the window sashing, completely saturating it. The sashing then drips water from every seam.
We have employed a steadily growing army of plastic cups to catch the drips, but it quickly became clear that we'd have to address the source of the problem. So as soon as S returned home from skiing, we marched outside, balanced ourselves atop ladders, and chipped away at the offending ice. Luckily S has a pair of ice axes from his ice climbing days, it would have been a much worse job without them. (We did this even though all the ice dam removal pages we found through google said "don't chip away at it!" What can I say, we were desperate.) Let me also say, ice axes are really sharp and pointy, and I've been known to make glancing blows at myself accidentally with the backsides of hammers, so this really intimidated me. Not to mention the fact that the ice shatters and flies everywhere when you hit it, which conveniently happens to be at eye level for me. So I donned my ski goggles, which made it so much better. We must have been quite the sight for the neighbors.
The dripping has slowed now, we're sitting around with crossed fingers and umbrellas.