Barn Swallow flock returns

The bright green burst in the center of the image above is the flock of Barn Swallows leaving their nighttime roost in a corn field along the Willamette River in Yamhill Co., Oregon. The image was made by NEXRAD weather radar at 6:00 a.m. on Friday morning, Aug. 24, a few minutes after the flock lifted off from the field on the west side of the river and began to drift eastward. The link to the NEXRAD site is
http://www.wunderground.com/radar/map.asp. Then click on the "X" in Oregon to go to the link to the radar facility that covers the northwest part of the state.

Weather permitting, it should be possible to watch this event live as it is repeated daily until early October.

A published paper providing more background information about this phenomenon can be found at:

http://www.engr.washington.edu/epp/psgb/2007psgb/2007proceedings/papers/P1_couse.pdf