PNW Migration Update – 17 April 2013

A decent night for flight; light NNW winds with gentle, diffused rain cells.  Migrants were in the air at moderate levels of 10 to 20 dBz.  Flight was sustained throughout the night so we should have had a pretty good turnover last night.  Birds will be dispersed but suitable habitats would be worth checking out for new arrivals.

The current weather pattern persists: high pressure ridge to our west and low pressure troughs forming in the Gulf of Alaska.  The interaction zone is the Pacific Northwest so we get NW winds with a few instabilities.  I don’t see that changing in the near future either.  I’m looking for another night of migration pattern pretty much like the past couple of days: moderate movement on clear skies and patchy movement through rain cells as they arise.

Nationally the extent of migration is being dictated by weather as always.  There is a wide ranging front from Texas to New York putting the breaks on northward advances.  Local fallout conditions will arise at the intersections of birds and weather.  Trans-gulf migration is in full swing.

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