Okay, in Kelso, I've only seen those visible easily from the freeway, but I've seen two from the freeway. One of them is siren no. 3 on the map, on Burcham St. But there is, or was, another Thunderbolt a little ways north of there, also on the east side of I-5, its pole mounted less than 15 feet from the freeway. I don't see it on the map, but on my last trip I looked and thought I missed it. Is it not on the map because it got removed in the past few years?
Edit: I found the one south of Kalama, on Todd Road, but I thought I'd seen one north of Kelso a bit, also immediately beside the freeway. I could easily be thinking of the one down south.