Migration Weather Special Report: Hermit Warbler

[Bryan Guarente]

I need to congratulate Luke and Tracy Pheneger for finding the Hermit Warbler in Melody Tempel Grove this morning!  Great find!  For me, this is a great data point because bird migration in the Intermountain West is a messy world.  This bird is a great data point!  Let's analyze some of the times before now and see what we can find out about the appropriate wind patterns aloft to produce Hermit Warblers in CO.  So again thanks to Luke and Tracy Pheneger for finding the Hermit Warbler so I can write such a fun post...

All but three Hermit Warbler records in Colorado happens in the last week of April or the first two weeks of May.  This should lead you to look at timing of Hermit Warbler migration, but also to ask the question (if I haven't trained you well enough yet) of what makes these weeks interesting for winds from Hermit Warbler territory?  I cannot answer that question easily aside from analyzing what is currently happening to get this Hermit Warbler into CO.

This warbler's story likely starts on May 3rd, but we cannot guarantee what time, so here is a guess (feel free to look at the times around this too to get an idea of what I mean):

https://earth.nullschool.net/#2020/05/03/2100Z/wind/isobaric/850hPa/orthographic=-102.78,38.22,1325/loc=-102.780,38.220 (Green Circle is Melody Tempel Grove for reference)

The winds over the Desert Southwest (not knowing exactly where this bird originated from we can only generalize) are broadly southwest winds and end up traveling into southern CO.  Over the next six hours, you can watch the convergence of winds over SE CO to see that the SW winds are consistently projecting into CO from the Southwest US. Let's watch this over time below and I will walk you through what I see.

6pm Sunday: https://earth.nullschool.net/#2020/05/04/0000Z/wind/isobaric/850hPa/orthographic=-102.78,38.22,1325/loc=-102.780,38.220

Continued SW winds pointing into southern CO with a convergence zone SW of Melody Tempel Grove

9pm Sunday: https://earth.nullschool.net/#2020/05/04/0300Z/wind/isobaric/850hPa/orthographic=-102.78,38.22,1325/loc=-102.780,38.220

Continued SW winds pointing into southern CO with a convergence zone now just SW of Melody Tempel Grove

Midnight Monday: https://earth.nullschool.net/#2020/05/04/0600Z/wind/isobaric/850hPa/orthographic=-102.78,38.22,1325/loc=-102.780,38.220

At this time, there is likely a frontal passage near the surface that likely grounds the bird due to northerly winds.  

3am Monday: https://earth.nullschool.net/#2020/05/04/0900Z/wind/isobaric/850hPa/orthographic=-102.78,38.22,1325/loc=-102.780,38.220

At this time, assuming the numerical model is correct, there would now be a solid convergence over Melody Tempel Grove and birds won't likely move from this location as the lowest pressure is upon them.  

6am Monday: https://earth.nullschool.net/#2020/05/04/1200Z/wind/isobaric/850hPa/orthographic=-102.78,38.22,1325/loc=-102.780,38.220

Continued Northerly winds holding the bird in place... and this pattern continues through today (May 5th).  

This pattern loosely continues until 6pm May 5th (this evening) where there will be a mixture of northerly and southerly winds since the grove is right under the convergence zone again.  This likely means VERY NICE conditions at Melody Tempel Grove tomorrow May 6th.  

https://earth.nullschool.net/#2020/05/06/0000Z/wind/isobaric/850hPa/orthographic=-102.78,38.22,1325/loc=-102.780,38.220

Over the following forecasted 12 hours, it looks like the convergence moves south of the Arkansas river into the Raton Mesa region of NM, but this doesn't mean there won't have been the addition of birds in the overnight hours.  

https://earth.nullschool.net/#2020/05/06/1200Z/wind/isobaric/850hPa/orthographic=-102.78,38.22,1325/loc=-102.780,38.220

So, if you are in SE CO, keep your eyes peeled for an injection of more birds (and likely convergence of birders).  My prediction is this will get better in terms of the density of birds at Melody Tempel Grove, or anywhere along the Arkansas River.  

With how many Arkansas River forecast convergence zones I have predicted so far, no wonder the folks down there love April and May, and why lots of birders travel that direction to find nice migrants.  Good luck down that way!

NOTE: This email does not mean you should break any laws or restrictions from your local governments.  

Thanks and Great Find!

Bryan

Bryan Guarente

Meteorologist/Instructional Designer

UCAR/The COMET Program

Boulder, CO

[Robert Raker]

Thanks Bryan!

Nice travel disclaimer. 😉

Rob Raker

Lakewood, CO

[Jean Stevenson]

Hopefully we will all be able to meet and bird in this important area early next May 2021 for the CFO Convention.

Jean Stevenson, Aurora CO

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[Adrian Lakin (adrianlakin1@gmail.com)]

Hi Bryan,

This is fascinating. Keep them coming.

Thanks,

Adrian Lakin

Mead, CO

On Tuesday, May 5, 2020 at 8:59:39 PM UTC-6, Bryan Guarente wrote: