The only creatures that watch the sky more carefully than meteorologists are…well… birds.
Our feathered friends spotted a perfect meteorological situation for their flights south and headed into the sky in great numbers on Thursday morning.
Nothing shows up better on weather radar than a nice plump bird. To illustrate, below is the radar image at 3:30 AM Thursday morning that combines all Northwest radars, with the shaded area showing radar returns (greens show more reflected radar signal than blue).
Normally, radar shows mainly precipitation, but none was falling at this time. This time it was birds, all birds.
From the intensity of the radar echoes there were a LOT of birds in the air. Note that birds don’t like to fly too far offshore.
And don’t think there were no birds over southern Oregon. No low-level radar coverage there.
The national bird migration website, BirdCast, makes intensive use of weather radar to track birds. Their analysis at 2:40 AM on Thursday morning shows the intense migration southward along the West Coast.
The migration was less on Wednesday morning and this morning.
First, birds prefer not to fly in the rain, and who would blame them for such a preference? And earlier this week it was raining.
Second, they like having a tailwind…yes, literally a tailwind. And they hate a headwind.
Let me show you the wind situation at approximately 5000 ft (850 hPa) at two times: when the birds mainly stayed on the ground and later when they took to the skies.
On Wednesday morning at 2 AM, a low center was found near our coast and moderate southerly (from the south) winds were found over western Washington and Oregon. Winds are blowing in the wrong direction for the migration south!
But on Thursday morning, the low center is gone and the winds are weak from the north over some of western Washington. A bit warmer. No rain. Bird migration paradise.
During the next week, a series of storms will be moving through so the birds will have to keep watching the sky.
