I apologize @Ruin , Some nights I tend to over indulge in Grams old fashioned Nug top Cake . I'm sure there are more ways this could happen than I am aware of. All I am saying is there can be air aloft of a different temperature that can get mixed in , or warmer/cooler air nearby that can work its way in/out , expanding ,shrinking or simply just moving in slowly. These guys here are incredibly cold shouldered to nubes around here that don't kiss the back side , and my humor can certainly be offensively confusing when it's even humor lol . There are plenty of guys here that could have given you a great answer quickly, but because you question the computer and media gods that can't get a single synoptic detail correct a majority of the time inside 48 for a huge chunk of the US unless the pattern is locked , so you have very few friends around here . I suggest you look up mesoscale analysis on YouTube, and you will find your answers there in time.