UFO Sighting in Issaquah, Washington on August 30th 2015 – Saw a blinding bright streak fastly descending in the evening sky

I was at a local park with a friend of mine sitting on the swingset and talking. It was early evening, getting darker but still plenty of light - the sky was still blue. There were some clouds but they were light and only covered about 40% of the sky I would say. Both of us were looking out at the sky in front of us. The park is on a very slight hill, enough of a hill to put us at about the same height as the two-story house's rooftops across the street in front of us. There is a small marshy forest behind us, a public outdoor swimming pool to our left, a retention pond to our right, and a tennis court, a two-lane boulevard, and some houses in front of us. We are sitting almost directly under some powerlines that stretch for miles in front of and behind us. We are sitting on some swings side by side and my friend is bent over tying his shoe. I'm still staring straight ahead. I see a bright flash and immediately ask my friend if he saw it too. He says no - he was looking at his shoes. This flash is unlike anything I've seen before. Sort of like a falling star but huge. I've worked in metal shops before and staring right at the flash is kind of like staring at welding torch's flame. Different colors but the same intensity. I can see it for at most five seconds, it is gone quicker than I can properly process it. Bright, bright white, maybe a little green or even pink around the edge, like a huge streak of TV static falling down the sky. It appeared out of nowhere close to the horizon and quickly dissapears behind it, falling diagonally and so so fast. I think it was comet-shaped, but so bright I can't be sure. It looks very small and very far away, miles and miles away I would guess. I remember just being very, very confused and wondering why a shooting star was out so early, how it was so bright and slowly thinking that it couldn't be a shooting star could it? I regularly go watching for shooting stars at night so I've seen my fair share, and even the biggest ones I've seen didn't compare to this. It was bigger around, much faster, and fell at an angle I don't see stars fall at. I ask my friend if he saw it, he says no, I describe it to him, and he says maybe it was a crashing plane or something. We both agree it couldnt be. We stay there watching the sky for about another hour to see if we can find anything else before giving up and moving on to meet up with some other friends. I get a little excited and tell a bunch of my friends about it, sending them a picture of the evening sky taken minutes after I saw the flash. Sadly I no longer have that photo, though I have no idea if it could've done any good. I feel confusion and excitement are pretty reasonable things to experience and don't think my mental state was affected much, if at all, by this. If anything, it gave me an odd sense of calm but I was already feeling pretty relaxed so I couldn't blame it all on that. I have waited almost a month to make this report because a) I've been trying to figure out exactly what it was I saw and b) I wasn't sure if it was a big enough deal to make a report on. I figure it couldn't hurt though. And I can't think of anything reasonable that this flash could have been. Regardless of what this streak actually is it isn't something normal, it isn't something that I have ever seen before, not something anyone I know has seen before. It's weird and I can't explain it. Thank you for your time and I hope this helps you out somehow.