First image is of the winds aloft at 850 mb (approx 5000 ft). Winds are moderate and out of the NW behind the latest cold front. Migration ready birds have nothing really holding them back except the occasional shower which they can avoid if necessary. In fact there was a fairly heavy flight last night
Second image is of the surface winds and pressure. You can see how the relative low has slipped inland just a bit leaving the strong NNW winds still offshore.
Third image is a snapshot of the base velocity showing north to north to south directionality at a peak of 15 to 25 knots.
Fourth image is the animated gif with snapshots every half hour of the base reflectivity above radar station RTX. The radar was in precipitation mode last night so density readings are shifted a bit. Animation runs from around 8:00 pm pdst yesterday evening through 5:00 am pdst this morning. (Click on the thumbnails to view the full-sized images and animation.)
Sunset last night was at 6:44 pm pdst.
Below is a snapshot of the national mosaic at 10 PM PSDT. The conditions remain the same as yesterday with a bit more wind assist along the eastern seaboard. Look back at the 850mb winds and you’ll see why the Central and Mississippi Flyways are devoid of birds.