Mon 17 Oct 2011

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

Second image is of the surface winds and pressure.   Over Oregon the surface winds are light.  Shouldn’t pose any barrier to southbound birds.  The fairly strong high pressure system currently off the coast should provide some nice weather for both birds and birders.

Third image is a snapshot of the base velocity showing the north to south directionality at a peak of 15 to 20 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 Portland last night.  Heaviest densities, up to 25 dBZ, were to the east along the west side of the Cascades.  There was no event to concentrate these birds so i’d expect them to be well dispersed across the favorable landscapes.

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 there was a significant lack of migration relative to the movement over our area.  With the observations of Shrikes, Swans, and Snow Geese being reported we may be on the tail end of this season?  Anyway, without many birds in the pipeline migration birding will slow down.  However, winter birding in the area is fantastic and the ducks are beginning to come out of eclipse plumage — my favorite time of the year.

Sunset last night was at 6:24 pm pdst.

Good birding!