Tues 18 Oct 2011

The blog is going into winter hibernation.  This will be the last post of this migration season but i’ll be back in the spring once the radar lights up.  See the post titled “Supplemental” below for more information.

First image is of the winds aloft at 850 mb (approx 5000 ft). Light and variable with a east 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 and variable.  Shouldn’t pose any barrier to southbound birds.  The fairly strong high pressure system remains off the coast but sliding a bit further north which is kicking up some stronger winds offshore.

Third image is a snapshot of the base velocity showing an interesting NE to SW directionality at a peak of 15 to 20 knots.  Really, this is the first time i’ve seen that type of directional movement.  I doubt it is because of the wind and suspect is it is a particular species pattern.

Fourth image is the animated gif with snapshots every half hour of the base reflectivity above radar station RTX.  There was movement over Portland last night but it wasn’t particularly dense.  I do suspect we’re on the tail end of the season.

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.)

Sunset last night was at 6:22 pm pdst.

Good birding!  See you in the spring.