Here is an image of the snow falling off the roof, taken on Saturday. This snow was very powdery, so the snow broke up as it left the roof. When there is ice mixed it, or it is a very wet snow, the snow comes down in large pieces.
After last years ice storm, the entire rear roof covering came down at once, in one large chunk. The front did the same a few hours later, when the sun had warmed that part of the house. When it struck the ground, large pieces were sticking vertically, like large icy tombstones. Fitting, had anyone been standing under there when it fell. On the Northwest corner, where there is no concrete walk, some of was embedded in the soil where it hit.
I thought I had taken pictures of it, but I haven't found them.
BTW, here is the rear of the house, showing the proximity of the trees.
And here is the creek that runs behind the house: