I dont know much about the technical terms, but being an avid tracker myself and staying at las vegas, my simple explanation can be this:
During the evening times, the flights tend to take off from the east to west direction irrespective of the destination…the flights heading towards north east destinations such as new york, chicago etc tend to make an immediate turn once up in the air towards north east…u must have seen some flight following the similar path…
i hope u understood it…sorry for my rugged answer…
