I got a referral for a roofer from a friend. I called them, and they going to send someone by in 2-3 hours to do an emergency patch and give an estimate on a more thorough fix.
Most of the water is running down the inside of the main exterior wall, so I hope I don't end up having to replace that too because of mold or something later.
Roofing crew showed up and inspected the roof. They discovered over six inches of standing water up there (it's a flat roof), and said I was in danger until it's cleared off. They managed to get the drain open again and cleared it out. I took a video of the water flying out, which I'll post after I do some minor editing.
They recommended replacing the roof entirely, and are going to give me a quote to that end.
Ugh. I wasn't planning on spending that much money right now, but I guess I'm lucky enough to have savings for this kind of thing.
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