6 May 2018:
How to predict a great birding day in early May? Find out last night’s weather.
At this time of year migrating songbirds spend the day eating and resting, then fly north overnight. Their decision to move depends on the weather. Here’s what they like best:
- New leaves on the trees at their destination. (The Leaves! article explains why.)
- A south wind, preferably a light one.
- No rain, no storms. If they’re flying north and encounter bad weather, they land right there!
- Pent up desire: If they’ve had to wait for good weather, the first favorable night will see huge movements of birds — thousands and thousands.
Weather radar is sensitive enough to show rain and snow. Did you know it also shows migrating birds?
The screenshot above shows the central Great Lakes weather radar at 4am, 6 May 2018. Yellow, orange and red indicate rain of increasing intensity. Green and blue are either light precipitation or birds. Green circles with blue edges are birds. Birds show up as circles because the detection limit of each radar installation is circular.
So what does this radar plot mean for Pittsburgh? Here’s a marked up version.
The red circle shows an area of bad weather. (Heavier rain is yellow and a hint of orange.) The red line marks the northern limit of the bad weather. Notice that there are no green circles north of the red areas. The birds stopped south of there.
Bad weather stopped the birds last night. Will we see the same birds in Pittsburgh today as we did yesterday? And in the same places?
Let me know what you find out.
p.s. Click on the radar images above to see the current Central Great Lakes radar map at weather.gov.
(screenshots of Central Great Lakes weather radar, 6 May 2018, 3:58 EDT from weather.gov)