I took photos of all this, so I really should post the followup. On 4 January we had more snow, drifted again from the back of the main roof to the garage roof, obscuring my studio light again.... but even if we pushed a hole in the drift from the window again, the weather forecast worried us.
The weather was warming, and by 5 January, we were sure the morrow would bring rain, and temperatures over 10C - that's ten degrees above freezing! I imagined all that snow on the garage roof filling with rain like a gigantic, soppy, heavy, sponge. Even if the garage roof did not cave under that weight, I didn't like the thought of all that waterlogged snow freezing into a giant block of ice, and stay that way until it one day slips off onto the hood of the car. I was really feeling gloomy about this when Judy came to work on the 5th. When I explained my foreboding to her, she offered to go out the window and shovel off the roof, with the enthusiasm of a rock climber with cabin fever! So she and Fred tied a rope around her waist, with the other end wrapped around the handle of a dipnet braced inside the window, and out she went -
our garage roof hero!