Migration Weather Advisory: Monday (May 11) Northern Front Range

[Bryan Guarente]

COBirders,

Tomorrow morning (6am) is one of those times that I hope to be really right because it looks amazing for bird migration into the Northern Front Range (from Denver through Fort Collins).  The low-level winds are funneling into the Northern Front Range.  Think of the Northern Front Range as the small end of the funnel.  The opening of the funnel (the other end) is from Houston to Del Rio, TX.  Let me show it to you here:

https://earth.nullschool.net/#2020/05/11/1200Z/wind/isobaric/850hPa/orthographic=-105.10,40.19,3000/loc=-105.000,40.000 (Boulder is the green circle)

Track any single streamline that touches the Northern Front Range to its "origin" and you will get what I mean.  I will also attach a few images as well to show you the funnel at different times.

Now, this could mean just that the winds happen to be opened up to migration at that time only, which would be a bummer.  But, lo and behold, the winds are like this starting tonight around Midnight.

https://earth.nullschool.net/#2020/05/11/0600Z/wind/isobaric/850hPa/orthographic=-105.10,40.19,3000/loc=-105.000,40.000 (Boulder is the green circle)

I think there are multiple other places along the Front Range that have a chance of getting migratory turnover (most of Eastern CO) and some areas of lesser convergence (between Pueblo and Rocky Ford) but the best convergence is up here in the Northern Front Range and points directly into the mountains which is really nice for meeting the greatest population densities.  

If you wonder about whether this is starting to occur or not, you can go check the radar and see how it looks for migration.  An easy way to do that is with Cornell Lab's birdcast:

https://birdcast.info/live-migration-maps/

This is derived from radar imagery and gives you some clear indication that this is going to be the case tomorrow morning as the winds are starting to come into line with what is posted in the midnight link above.  

So, my recommendation, as usual, is to get out birding locally (abiding by all social distancing and local regulations).  Prove me right or wrong.  More datapoints = more clarity.  Best of luck with the winds and I wish you great birding tomorrow!

Thanks,

Bryan

Bryan Guarente

Meteorologist/Instructional Designer

UCAR/The COMET Program

Boulder, CO

[Steven Rash]

Bad weather, good birds wins again for us in SE Denver. We had 50 species at Overland Pond Park. This is 10 more species than our best effort to date, including 4 previously unreported birds for the hot spot. Highlights were a green-tailed towhee, female lark bunting, a common yellowthroat, lazuli bunting, and MacGillivray’s Warbler.

Thanks again for the forecast!

Steve Rash
Denver Co.

[Bryan Guarente]

Great to hear Steven!  Glad you had a good morning, and I hope your day continues in the same way.

Your intensification of birds into your area jives with what I saw up my way in Longmont.  I didn't get anything particularly amazing but did get 50 species for the first time in one hotspot this year.  That was a jump of about 13 species from my previous high species counts.  This is another way of verifying migration and I think it is worth others noting their experiences today.  Increases in the density of individuals (twice as many yellow-rumped warblers as yesterday) or increased diversity of species (50 species instead of 37 in previous recent visits) can really show some great data.  Not all days are going to be "rarity" days.  

If you haven't emailed me directly and want to reach out to COBirds to let us all know, that would be great to hear.  More data is a good thing even if it means proving me wrong.  I am prepared for that reality.  

Thanks,

Bryan

Bryan Guarente

Meteorologist/Instructional Designer

UCAR/The COMET Program

Boulder, CO

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[Adrian Lakin (adrianlakin1@gmail.com)]

Hi Bryan,

We just had a flock of at least 30 Chipping Sparrows in my backyard in Mead. Previous high count was 1!

Adrian Lakin,

Mead, CO (Weld county)