Migration Forecast Thursday Oct 5: Heads up

[Bryan Guarente]

COBirders,

I've been waiting for a good migration forecast to come together for CO as the migration season is passing us by, what feels like, pretty quickly.  This Thursday has the potential to be a good day for Coloradoans.  Here is 6am on Thursday Oct 5 (green circle is Longmont, CO, but feel free to move around in time to see when the front is near you):

https://earth.nullschool.net/#2023/10/05/1200Z/wind/isobaric/850hPa/orthographic=-108.66,43.60,1918/loc=-105.120,40.191

The forecast calls for frontal passage at 850mb to be right around sun up for a bunch of Colorado.  This means any birds looking for a meal after traveling overnight behind that front could put down in your area at sun-up to get some chow.  The origins of this frontal airmass are Northern Canada, with our local winds maybe only originating from WY/MT depending on how the forecast pans out.  

There are no strong areas of convergence for birds to concentrate on, so expect that we will see an increase in migrants overall, but no particular location getting the best of it based on the weather (based on the food sources, that may be a different story).  

Best bets: Eastern plains lakes/reservoirs.  

Also, if you have any desire/need to chase the Kansas American Flamingo, you should probably do it before Thursday, because my educated guess is this bird will move on with this frontal passage.  And it will be moving southeast, not west, no matter how much we want it to.

I'll keep you posted as this week moves along.

Thanks,

Bryan

Bryan Guarente

Meteorologist/Instructional Designer

UCAR/The COMET Program

Boulder, CO

[Bryan Guarente]

Hey COBirders,

Here is an update to the previous migration forecast.  

There isn't much change from last forecast except that there is a longer period of time when migrants could be coming into the Front Range.  Instead of it being a quick blast of winds into the Front Range with a passing cold front, the front will hang up a bit on the Raton Mesa (southern CO/northern NM) and should give us a longer period of time with winds turning into the Front Range (All day Thursday instead of 3-6 hours).  Here is the "best-looking" map to show you what I mean: https://earth.nullschool.net/#2023/10/06/0400Z/wind/isobaric/850hPa/orthographic=-101.79,44.36,1404/loc=-105.254,40.036 (10pm Thursday night; Green circle is Longmont).

Bird concentrations should pick up with the frontal passage tomorrow morning (early morning for Northern CO, later morning for southern CO).

Still, I am not seeing any specific areas where birds will concentrate due to the wind pattern.  It looks like a broad brush of birds along the entire Front Range.  The overall pattern and connection to the Arctic should give higher probabilities of bird concentrations on the Eastern Plains of CO and into KS, but if you aren't willing to make the drive, there should be birds showing up all along the Front Range so don't feel like you will be missing too much.  

Please provide updates as you have them tomorrow and beyond.  All data is good data.  And help keep me honest by letting me know if the forecast is "right" or not for your area.

Good luck out there!

Bryan

Bryan Guarente

Meteorologist/Instructional Designer

UCAR/The COMET Program

Boulder, CO