Roof valley water backup.

The pool of water that has built up behind the roof eave ice dam. At this point, about two feet up the valley, the water is about three inches deep. As it can't get past the ice below, the water will run horizontally and seep under the slate until it finds a hole. It does'nt take long for the water to find a nail hole, or in this case, a gap in the old deteriorated tar paper, and find it's way into the interior of the house.