Well that's something i haven't seen :blink: That's the nice thing about the Wasteland, you see weird things.
The Firelance event leaves a similar smoketrail as the (endgame MQ spoiler)
Spoiler
mortars the enclave fires during the Take it Back! quest, as well as the Talon Company artillery support near the Capitol Building and in Takoma Industrial
. I've never seen or heard of a bug like that though.
Were you near Megaton by any chance? I saw some clouds sort of like those on my way back from the Super Duper Mart (I think that's it's name, the store just west of Megaton.). I thought to myself all this time playing FO3 and now it's going to rain for once.
I once had a enclave vertibird's smoke trail get stuck in my sky as it flew off. Might be that?
S'what I was thinking. I can often see a Vertibird in the sky that hasn't quite vanished from sight. One of those that do the fly overs all the time, or the one's dropping off troopers. Could be one he's shot and that's smoking, still stuck in the sky.
I usually see them stuck in the sky around the Mall.