Yeah, I’ve had that happen to me just south of Flagstaff too.
But the worst case I ran into was just south of Denver on I-25 on Monument Pass. Not much of “pass” by Colorado standards, actually pretty similar to interstate just south of Flagstaff, just windy enough that there’s some blind corners where you can enter the corner in full clear and run into a zero visibility fog bank in the middle of the turn.
And just like Flagstaff, just a little band of Armco between you and a several hundred foot drop.
Yikes! I forgot to say that was I-17 (as you know) — and you’d think it would be marked. There are so many spots marked “icy bridge” or “watch for ice” or whatever — maybe “watch for fog” would be helpful. I had no idea it was so common there, until after it happened to us and then all of our friends said “oh yeah, that happened to us too.” (We only go up there about once every couple of years.)
Oh, scary about Denver.