Thurs 24 May 2012 – PNW Migration Update

The low pressure system offshore to our NW continues to weaken.  The competing high pressure ridge organizing off the California coast is asserting itself – but mainly to our south. We’re still getting the SW winds and the occasional rain shower.  Last night local migration was detectable between the clouds and rain.  There was a rather heavy movement in the west counties from McMinnville to Hillsboro and along the N-S section of the Columbia.

In the field the migration news on the listserves shows some migrants still around and a few rarities. Like the Stork in the Rogue Valley, Black Swifts here and there, Whimbrels still in the area, and oddball Sandpipers. Checking in on eBird for Multnomah and Washington Counties arrivals, we find nothing new in the area.

The outlook for migration over the next few days continues to be dependent on the timing and occurrence of rain and, most importantly – a supply of birds.  The wind is forecasted to begin shifting to mainly westerlies throughout the day.  As the fronts move east and compete it looks like the high pressure ridge has the edge but the forecast is for mixed weather through the weekend.

Regionally migration in the Rogue Valley was minimal at best.  Being quite a bit further south they are still seeing northerly surface winds and westerlies aloft associated with the frontal boundaries.  Again, I’m not sure if that is what is holding up the birds or just the tail end of the season.

The Californian portion of the Pacific Flyway has a couple of pockets of heavy migration around the Central Valley.  Overall migrant blooms are moderating.

Nationally the weather is still favoring the southern portions of the Central Flyway and most of the of the Mississippi Flyway up into the Ohio Valley. We find the birds are still pinging heavy returns over the Mexican and Texas borders, but definite signs of moderation are being seen. The Dakotas had a few hot spots behind the storm front that can be seen from Colorada to Minnesota .  The Southeast look to be spent; we haven’t had any significant movement there in a while now.

As always — For more detailed migration updates in other regions check:

Wisconsin and New Jersey – woodcreeper  by David LaPuma (currently on hiatus – 5/21)
Michigan’s Upper Peninsula – The Northwoods BIRDAR by Max Henschell <- NEW!
New England – Tom Auer’s blog
Florida/SE – Badbirdz Reloaded by Angel and Mariel Abreu
PA/Ohio Valley – Nemesis Bird by Drew Weber
NW Ohio – Birding the Crane Creek by Kenn Kaufman
Arizona – Words About Birds by Tim Schreckengost <- NEW!
New Mexico – Albuquerque Birding by Matt O’Donnell <- NEW!
Continental US – eBird BirdCast Forecast & Report by Team eBird

Also found under NEXRAD Trackers in the sidebar to the right.