The Great Migration: Birds on Radar

April 26, 2011


Tonight’s radar shows the last few showers dying out as the evening goes on, but it also shows what I consider a remarkable sight.  The spring migration of birds north into Canada and the Arctic.  Check out the image at 8:45pm, then compare it with one hour later.  Do you see the sudden explosion of echos in the Willamette Valley?  Those are migrating birds.  How do we know?  For several reasons.

-This only appears in Spring and Fall

-Our wind between 1,000′ and 10,000′ is light westerly tonight, but THESE echoes are moving straight south to north at 25-35 kts!  Those guys/gals are in a hurry to get up north and get on with the family-making!

-A study presented to television meteorologists a few years ago at a conference pointed out that it only takes a few geese for an echo to show up.  It’s not like there is a “wall of birds” moving overhead, but there is plenty of avian action!  Remember the surface area of a goose or duck (along with smaller birds) is significantly greater than a hail stone.

-The birds prefer to fly at night since there is less turbulence in the atmosphere then.

Now maybe I read too many issues of Mother Earth News while on vacation, but I think mass migrations are fascinating.  Year after year these birds, much smaller than us, fly thousands of miles TWICE.  So while you sleep tonight, think about the thousands of birds working their way north over your head.

By the way, it’s not exactly a party movie, but my kids enjoyed Winged Migration, a movie about this semi-annual phenomenon.

As for weather…more rain coming the next 3 days!

Chief Meteorologist Mark Nelsen