Peaches
JimmyG–I’m not sure how big the trees off your alley are, but I’m wondering if they are big enough to host a roosting raptor/owl. Since your war starts at dawn, it may be the crows are coming off their roosts (they roost communally in at least one place along the Duwamish River), and happen upon a raptor that sleeps in a bit. I always know there’s a raptor in my area, as the crows go ballistic when a red-tail hawk or eagle lights on a limb of the big cottonwoods behind my house. The crows can’t seem to get out of their own way in their efforts to dive-bomb the hapless raptor, even crashing into each other in flight. And the crow-racket that gets going must be some kind of APB, as it seems to attract even more crows that appear from every direction.
Crows are also familial–youngsters generally hang out with the parents for a year or two after fledging. Not sure how much food competition there is between generations, but I’ve seen full-grown crows begging to be fed by equally full-grown crows. Could be some kind of extended family feud going on in your backyard!