Migration Forecast: Thursday and Friday August 18/19

[Bryan Guarente]

CoBirders,

It has been a nice summer including some unexpected migrants that have made little sense meteorologically (Red Knot).  

Here we are though at the edge of Summer/Fall and amply into the monsoon season (yes, it is a thing --> ask if you want to know more).  What does this mean for ornithological migration?  It means mostly shorebirds, but we are getting close to the earlier migrants.  Where are most of our shorebirds coming from?  The northern prairies into the Arctic of Canada.  

So look at this pattern:

https://earth.nullschool.net/#2022/08/18/2000Z/wind/isobaric/850hPa/orthographic=-105.93,52.84,1333/loc=-105.120,40.191 (Green circle is Longmont, CO for reference). 

What do you think will be coming our way on Thursday?  By midday on Thursday, it looks like we are set to receive 850mb winds from the correct direction to see a good push of migrants from the middle of Canada, likely mostly shorebirds, but some of the earlier passerines are possible.  It is also possible that some of your locals will be leaving you if they are earlier migrants so get in your goodbyes while you can. 

Later that evening, the winds look better, but that doesn't last forever: 

https://earth.nullschool.net/#2022/08/19/0400Z/wind/isobaric/850hPa/orthographic=-105.93,52.84,1333/loc=-105.120,40.191 (really good looking pattern, but with the wrong timing; Longmont is the green circle).  This pattern, although really nice, occurs at sunset and doesn't last through the night to make the migrants end up here in CO with as high of probability.  Here is what it looks like on Friday morning: https://earth.nullschool.net/#2022/08/19/1200Z/wind/isobaric/850hPa/orthographic=-105.93,52.84,1333/loc=-105.120,40.191 (Green circle is Longmont.). The wind strength has weakened and the convergence into Colorado is weaker, so we shouldn't expect a lot of movement overnight that ends up in CO, but it is worth a glance on Friday morning to see what has come in.

As usual, if you have questions, please ask.  I am here to be your guide to weather and migration.

Happy migration to you!

Bryan

Bryan Guarente

Meteorologist/Instructional Designer

UCAR/The COMET Program

Boulder, CO

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Bryan Guarente

Meteorologist/Instructional Designer

UCAR/The COMET Program

Boulder, CO