Copy paste from one of my recent posts: I've had this happen numerous times without True Storms installed while working solely on my weather mod Wander. While I'm not sure what the root cause is, it only ever happens to me when I either: - Forced the weather to change, which I've done thousands of times in testing Wander. - Fast traveled to new locations mid-storm while testing. - When I swapped versions of my weather mod while testing. These were all on existing saves while testing, I've never experienced this effect, myself, on a fresh save with a fresh game load with Wander or True Storms. Best that I can tell, it occurs when there is an unnatural transition in weather. Hope this helps.