Migration Weather Advisory: Tuesday All Day

[Bryan Guarente]

COBirders,

Looks like tomorrow should be a good day for migrational turnover.  Expect that birds from farther south will have a chance to migrate through the area on stronger southerly winds (FROM the south) originating from OK/TX.  Unfortunately, there isn't a strong convergence zone that would help condense the birds into certain locations. You can expect convergence of birds nearer the foothills than farther east as the mountains act as a natural convergence area when southeast winds are dominant.  This doesn't preclude the fact that good habitat attracts birds better than bad habitat.  So it can always be worthwhile to check your patch multiple times on a day like tomorrow (4/21)

Yesterday (4/19) and today (4/20), the winds aloft have been very weak promoting more soaring-bird migration but still allowing direct flight migrations as well with less wind support to cover ground.  Tonight and into most of tomorrow (4/21), expect the winds to be stronger aloft and from the south for most of the day making for a stronger possibility of turnover of birds.  

https://earth.nullschool.net/#2020/04/21/1200Z/wind/isobaric/850hPa/orthographic=-105.00,40,1897/loc=-105.00,40 (The green circle is on Boulder for reference only)

I hope you can get a chance to get out (I know it is a work-day) for at least a walk in your local patch.  You should have a nice opportunity for some new birds (First-Of-Year/First-Of-Season), but they may not stick around for long with continued south winds throughout the day into the night unless your patch has good habitat and food.  

May the meteorology bless you tomorrow with birds.  Remember positive and negative data are both useful to help us understand the overall meshing between bird migration and weather patterns, so let us know what happens for you tomorrow.  Best of luck.  

Bryan

Bryan Guarente

Meteorologist/Instructional Designer

UCAR/The COMET Program

Boulder, CO

[Robert Raker]

Your reports are are excellent and the information well presented and very interesting to us non-meteorologists. Thanks so much and would love to see them continue! 

Robert Raker

Lakewood, CO

[Patrick O'Driscoll]

I agree with Rob, Bryan.

Anecdotally, I kept an eye on a couple of my patches on Tuesday, given your "migrational turnover" weather forecast.

Wouldn't you know it -- I had a yardbird first of 7 Chipping Sparrows at home off Colfax in very urban east-central Denver, and a FOS Ruby-crowned Kinglet and an unexpected Osprey soaring overhead, both in Denver City Park about a mile from home.

Thanks again for your interesting and informative posts.

Patrick O'Driscoll

Denver

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[Allison Hilf]

I agree.  Bryan's reports are fascinating.   Besides the massive numbers of Marbled Godwit and Long-billed Curlew sightings yesterday, I noticed several eBird reports stating "FOS".   

Yes, that's one "advantage" of being one of the RBA Compilers - you see whats going on around the state while looking for the rarities.  Any volunteers out there???   We are very short-staffed, and if you can help with one week a quarter we would very much appreciate it.

Thanks Bryan, your posts are much appreciated.

Allison Hilf

Aurora, CO

[Dave Hyde]

A FOY White-crowned sparrow – yellow bill, Gambel’s variety – here near Storm Mountain in Larimer Cty. It is not here today – Dave/nr Storm Mountain