Migration Weather: Thursday Sept 2 through Friday Sept 3

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Bryan Guarente

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Sep 2, 2021, 8:24:01 AM9/2/21
to Cobirds
COBirders,
This morning, the cloud cover is relatively low, and I am sitting out on the patio right at sun-up to see if there are any birds calling while they are passing by.  No luck so far, but the winds aren't great for migration yet.  The day is young though.  Right now, the pattern looks like this:

NOTE: feel free to move the green circle to your location by adding your latitude and longitude to the URL.  After the "loc=", remove my longitude and latitude, add your longitude and latitude into that space making sure negative longitudes are "west".  Boulder, CO is right around 105W longitude which converts to -105.  Baseline Rd (named that for a reason) in Boulder is 40˚N which just converts to 40.  "loc=-105,40" will then be centered right near Boulder.

I have north winds overhead (but not at the surface), but the gates aren't opened for migration yet today.  Migrants are likely only short-range, if that.  Let's fast-forward to later: 9am

There is now a better connection to the large-scale northerly flow from Canada and the big cut-off low-pressure system up north (big spinning circle of streamlines).  Move forward in time a bit more: 6pm

The connection is now more obvious and the flow of migrants should be quite possible.  This is why Birdcast/Aeroecolab forecasts are starting to light up with migrants as Diana Beatty pointed us to on CFO's Facebook page yesterday.  

As the frontal passage continues to move on to the east (KS, NE, SD, MN), our winds end up n some nice concentrating patterns.  Map from 6am on the 3rd:

The big winners (in CO) seem to be in southeastern CO.  My initial click around the map pinpointing the location I was forecasting highest concentrations was just south of John Martin Reservoir.  So Lamar, John Martin Reservoir, and environs around that should be in for a good push and concentrations of migrants.  As Mark Peterson pointed out the other day with his Hale Crossroads observations, concentrations can happen along these northerly wind patterns where there is good habitat (even in small pockets), so if you are below the concentrating northerly winds get out for a quick look around that may turn into a long look around and some good migrants from Canada or anywhere along the path those winds took to get here.  

Best of luck out there.  May the birds concentrate in your area one day.
Bryan

Bryan Guarente
Meteorologist/Instructional Designer
UCAR/The COMET Program
Boulder, CO

Steven Brown

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Sep 2, 2021, 1:36:12 PM9/2/21
to COBirds
For what it is worth…. I checked Birdcast this morning pre-dawn, and was getting excited for banding possibilities at Clear Spring Ranch (El Paso Co). It was a dud. Maybe my slowest September day ever at CSR.

Few Chipping Sparrows (none netted), fewer warblers. Netted 8 birds all morning - banded 3, saw 2 more warblers. I DID band a young Red-eyed Vireo, and a Hatch-year Dusky Flycatcher, but it was SLOW.  The big events for the day were - (1) 500+ Common Grackles flushed from a field in one giant flock by a Prairie Falcon, and (2) 22 Western Kingbirds lining the fence on the way out - my second biggest arrival of those ever.

Hoping for more this weekend - 
Steve Brown
Colo Spgs

On Sep 2, 2021, at 6:23 AM, Bryan Guarente <bryan.g...@gmail.com> wrote:

COBirders,
This morning, the cloud cover is relatively low, and I am sitting out on the patio right at sun-up to see if there are any birds calling while they are passing by.  No luck so far, but the winds aren't great for migration yet.  The day is young though.  Right now, the pattern looks like this:


Bryan Guarente

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Sep 2, 2021, 3:18:20 PM9/2/21
to Steven Brown, COBirds
Steve,
I didn’t particularly think today was going to be good. Tomorrow is a better chance by a bunch. Birdcast, for clarity, is about whether there will be birds seen on radar. It is not necessarily about where the birds will land so be careful with that assessment. Birdcast certainly has its place in the conservation world and can inform the birding world (if those are different). My forecasts are a different role than what Birdcast offers and both, I believe, are beneficial just to different audiences. 

Good luck tomorrow. 
Bryan

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