Thurs 13 Oct 2011

First image is of the winds aloft at 850 mb (approx 5000 ft). Light and variable with a NNW bias.  Pretty good conditions for migration ready birds in the area.

Second image is of the surface winds and pressure. The low pressure system that was off the coast of BC the last couple of days has completely dissipated and has been replaced with a high pressure ridge a bit further inland.  Over Oregon the surface winds are light with an easterly flow.  Shouldn’t pose any barrier to southbound birds.

Third image is a snapshot of the base velocity showing the north to south directionality at a peak of 20 to 25 knots.

Fourth image is the animated gif with snapshots every half hour of the base reflectivity above radar station RTX.  There was significant movement over the whole range of the radar and heavy densities up to 25 dBZ.  There isn’t any prevailing barriers to movement so the birds will be well dispersed across the landscape. But usual concentration points should have new individuals in them today probably quite a few of them at that.

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.)

Taking a look at the regional mosaic we can see that to the north of us, while birds are on the move, it’s just not quite as dense.

Sunset last night was at 6:31 pm pdst.

Good birding!