Migration last night

Birds were on the move over the Northeast last night. The radar loop is from sunset last night through 8:30am this morning, and shows a moderate amount of migration over New Jersey. There is some anomalous propagation present, due to the significant difference in earth and air temperature after sunset (resulting in temperature inversion) but the velocity still shows objects moving across the radar at speeds +10-20kts faster than the prevailing winds (ie. birds).

Hopefully Bill gets a good day up on the hill…wish I could be there!
Good Birding!

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4 Responses to Migration last night

  1. Noel Wamer says:

    I rarely disagree with David’s radar interpretations, but for this night I would have concluded NMD – no migration detected. It is true that the radial velocities are faster than the surface winds — all New Jersey NWS stations that I checked indicated calm to light winds (<10 kts) from variable directions. However, upper air data at typical migrant altitudes show a high pressure center west of NJ. This would have produced winds in a north to northeast direction, very similar to the trends shown in the radial velocity images.

  2. HillBilly Bill says:

    I got a mention of the woodcreeper site!!!
    I did get some birds 40+ only 2 GCth but it was a good warm morning.

  3. David says:

    Noel and Bill, thanks for the comments.
    Noel, I think we’ll have to agree to disagree (or maybe we disagree that we actually agree…or something), since I think that some of the signal could be due to whatever is ‘blowing in the wind’, although I also think that some of it is due to migration. If you check the NCAR data (which seems to have its resolution set a little finer, ie. the signal is better divided into more colors) it looks like there’s a proportion of the total signal that’s moving at a significantly higher velocity than the prevailing wind ( Such as in this image from 3am ). Unfortunately when Rutgers set up their display they seem to have lumped the 0-25kts display a little more than they should have for discerning bird migration (although they really don’t care about it unless it’s precipitation anyway).

    Cheers! 🙂


  4. David says:

    hehe…a Scottsman calling himself a HillBilly…that just tickles me to no end.