In the first place, previous weather of the snowy kind. And then, current weather of the indeterminate kind—neither here nor there, neither this nor that—but in between—with the temperature just below the freezing point of water but close enough to it that the sun can exert its influence.

I have to say that everyone around here is pretty much done with icicles, and all their antecedent causes, as well as the factors contributing to their generation.