Last winter I posted a couple of times about a cool phenomenon, when snow settles onto our metal roof and slides, very slow, over days, toward the edge. In the right conditions, the snow bonds together into a sheet and, despite sliding over the edge of the roof, stays connected as a sheet. Yesterday I awoke to see these impressive sheets hanging outside my bedroom window, each at least two feet long.
I opened a window, and reached out to touch them. They were soft, fragile, and slightly wet, despite the 20ºF morning temperature. It had been warm (above freezing) the afternoon before, allowing them to slide slowly off the roof, but the falling evening temperatures trapped them in this frozen form.
Some time later that morning they fell off, as the temperatures warmed and a windy cold front arrived. This morning I see their impressions in the snow where it thinly covers the deck below.