Here you can see how the wind signature almost perfectly coincides with nocturnal avian migration on NEXRAD. Gulf winds across the southern United States, coming up into the midwest and then Wisconsin. Even as the wind angles out of the southeast it's still a tailwind and that's what birds want/need. They can double their flight speed and use less of their fat stores when migrating with a tailwind. Now through the end of May and part of early June you can observe migration on NEXRAD whenever the winds are out of the south.
