Tonight, as forecast, the winds have become unfavorably northerly, and the average concentrations of migration tonight are light to moderate. This is, however, a time of year where many birds cannot miss a beat to move northward, and out of the millions of individual migrants moving through our state right now, some of them are moving in heavy concentrations. Dividing the state up by thirds wouldn't be as useful tonight, so let's take migration tonight on a case-by-case basis.
Northeastern Illinois (see right) is somewhat isolated from the light migration in the rest of northern and central Illinois, as according to the radar, it is currently host to moderate to heavy migration. This may be because of some alteration of the winds caused by Lake Michigan, as migration is also heavy in southeastern Wisconsin. But beyond that, the reasons for such movement tonight in northerly winds is beyond me. But hey, no complaints here!
As stated, migration in the majority of the rest of the state is light to negligible except for Southern Illinois (See left). Much of Southern Illinois remains host to only light concentrations, but the further south you go, the closer toward moderate levels you get. By sometime tonight, it seems likely that the furthest southern radar station in Illinois will be relaying images of heavy migration, so to any of you southern Illinois night-owls, this may be worth keeping an eye on. Like in Northern Illinois, I have only a shaky hypothesis to explain this at best.Winds right around far Southern Illinois are actually almost due westerly, though most of these winds are south of Illinois. Without the northerly influence of the winds, birds may be utilizing the westerly winds. But that's all I've got. Regardless, there may still be some influx tomorrow!
So that's that. Other than the named exceptions, migration is basically light in the Prairie State.
The winds are set to change throughout the state pretty soon, folks (N & Cent. IL wind forecast: http://bit.ly/1gqPFCAv, S IL wind forecast: http://bit.ly/124R3WX). Late Friday night, winds are forecast to shift to be more easterly, and by early saturday morning, these winds are forecast to become southeasterly, a definite improvement from our current northerly winds. So we all have that to look forward to.
Anyway, here's the eBird frequency chart to check out what birds may be around right now: http://bit.ly/1nS3bao
And with that, I bid you all a good night. Good birding!