Okay, so here’s the base reflectivity image from sunset last night until sunrise this morning. Notice we get a strong signal after sunset (relatively speaking, since the radar is on “clear air” mode) but it quickly drops off after 10pm. The velocity image (from 9:30pm EST) shows some movement that could be birds, but it’s light compared to what we see in the base reflectivity*. This is likely due to some amount of anomalous propagation caused by the temperature inversion after sunset (AP has no velocity but shows up in the base reflectivity). My interpretation is similar to the past few days, where we see a small movement out of New Jersey first thing after sunset, and then a quick tapering off soon thereafter.

* for more information on how to interpret the velocity image, see the “Why NEXRAD and Birds?” link to the right