First image is of the winds aloft at 850 mb (approx 5000 ft). The winds up in BC are favoring inland exodus tonight and will be pushing birds toward the Central Flyway where the winds are out of the north and 20 to 30 knots. As migrants hit the gorge in our area they will encounter some 30 knot westerlies to contend with. Surface winds are quite a bit calmer so the birds might be migrating at lower elevations — like, right into buildings, towers and windmills.
Second image is of the surface winds and pressure. There is a high pressure system off the coast and there are some northerly winds along the coast that could entice some migrants to take to the skies.
The RTX radar was down last again night.
(Click on the thumbnails to view the full-sized images.)
Sunset last night was at 7:16 pm pdst.
Below is a snapshot of the national picture. Note the heavy density of nocturnal flight down the Central Flyway in response to the favorable conditions.