Thank you for your insightful guidance this Bryan. I'd like to learn more.
Is there anywhere to actually find instructions and guidance to use this site? This is obviously a valuable tool in the hands of someone who can actually use it!! Tim Tim Barksdale Choteau, MT Mokane, MO On Monday, May 3, 2021 at 8:54:08 PM UTC-5 Bryan Guarente wrote: > COBIrders, > *TL;DR (Too long; didn't read):* I don't know why the Hudsonian Godwits > showed up today in Boulder County, but I wanted to let you know some things > about numerical weather models that make them not always the best way to > answer the bird migration question I often pose on COBIRDS. There is more > to weather forecasting than just what the model data says. > > *Full story:* > Eric DeFonso spread the word this morning that there were 15 Hudsonian > Godwits seen at Lagerman Reservoir SW of Longmont in Boulder County, CO. > I was surprised to hear this as yesterday's frontal passage wasn't > remarkable for driving birds into the Front Range. Here is the pattern for > the same time that Eric reported these birds on eBird. > > > https://earth.nullschool.net/#2021/05/03/1500Z/wind/isobaric/850hPa/orthographic=-102.64,34.64,2728/loc=-105.187,40.138 > (Green > circle is the location of Lagerman Reservoir) > > Seems like quite the wrong pattern for birds to be coming into CO... hmm. > > So maybe we need to look late yesterday (sunset on May 2nd) to see what it > looked like then: > > https://earth.nullschool.net/#2021/05/03/0200Z/wind/isobaric/850hPa/orthographic=-102.64,34.64,2728/loc=-105.187,40.138 > (Same > green circle on Lagerman Reservoir) > > No better and you can see the cold front more clearly from Iowa through > Nebraska and into Kansas (blue squiggle of convergent winds on this > image). Again, it doesn't look like a good time for birds to be coming to > CO as the winds are from the north making most birds want to stop their > journey rather than face the north winds. > > Let's keep going backwards in time though. Here is 12pm May 2nd. I am > choosing this time for a reason that will become clearer later. > > https://earth.nullschool.net/#2021/05/02/1800Z/wind/isobaric/850hPa/orthographic=-102.64,34.64,2728/loc=-105.187,40.138 > (Same > green circle) > > Still in that same boat... not good migration conditions into CO. This > was the last observation time as well from a birder on eBird at Lagerman > yesterday... leaving a large window of opportunity for these birds to come > to Lagerman and go undetected until this morning. > > But this is where the story goes off course from my normal posts to > COBirds. The website data is from a computer model. Computer models are > right in many ways and I love their output for posts like the ones I > normally make. One of the ways that meteorologists are still important is > that we can sometimes tell when the model data needs some nudging to make a > good public forecast. Or we can use the observations in hindsight to > compare to the models and we can see when something was missing. This is > one of the latter cases. > > Let's look at a variable that I don't normally ask you to look at: 3-hour > precipitation accumulation. This is how much rain or snow accumulated over > the last three hours from the time of the plot. So at the following map > time, the data show precipitation from 9am until 12pm. > > > https://earth.nullschool.net/#2021/05/02/1800Z/wind/isobaric/850hPa/overlay=precip_3hr/orthographic=-102.64,34.64,2728/loc=-105.187,40.138 > (Same > green circle) > > The amount of rain near Lagerman Reservoir was expected to be .06 inches. > This is light rain for a bit. Nothing much. In reality, let's see what > was happening: > https://climate.cod.edu/data/nexrad/FTG/N0Q/FTG.N0Q.20210502.1653.gif. > > This is a pretty strong line of thunderstorms moving from west to east > that was barreling down the foothills to change the local smaller scale > weather pattern compared to the model output. This wasn't going to be a > little bit of rain for a bit. This was a thunderstorm that was meaning > business for those in the way of it. That radar image was a few minutes > after Boulder Municipal Airport had received .9 inches of precipitation in > the last *hour*. > > This is a major departure from what the model was saying! This model > wasn't expecting a thunderstorm like we ended up receiving. This means > that some of the local winds (at the surface and aloft) are likely > different by a large amount compared to the model output. This could have > led to a situation where the Hudsonian Godwits found a different pathway > through the meteorological pattern that we just aren't seeing in the model > data. I don't know for sure how the Godwits got here, but I am speculating > that this thunderstorm and its resulting change in the wind pattern as it > moved off of the foothills and out into the eastern plains of CO caused a > nice migration pathway to help them find Lagerman Reservoir. > > Now, since you have read this far, I have to give you something else to > work with. I believe the Hudsonian Godwits have a chance of sticking > around through the night if you didn't get your chance today. Here is > tomorrow morning (7am May 4th): > > https://earth.nullschool.net/#2021/05/04/1300Z/wind/isobaric/850hPa/orthographic=-102.64,34.64,2728/loc=-105.187,40.138 > . > > This is the first solid south wind for these birds to leave on. So if you > get to Lagerman at around sun-up, you have a chance of seeing these birds > in the morning. They may not last long after that though as the winds pick > up and give a nice south wind for these birds to migrate on. > > So when is the next chance of anything in CO? It looks like May 5th there > is a small push of migrants in the southeast. I would suggest a rectangle > from Cheyenne Wells south to Lamar, west to John Martin Reservoir, and > north to Kit Carson. > > > https://earth.nullschool.net/#2021/05/05/1200Z/wind/isobaric/850hPa/orthographic=-102.64,34.64,2728/loc=-102.370,38.802 > > (Green circle is Cheyenne Wells, CO) > > Hope you enjoyed this and get a chance to see the Hudsonian Godwits like > the 76 observers who reported to eBird today from Lagerman Reservoir > (compare that to three the day before). > > And lastly, if you are thinking ahead to the weekend and the CO Birding > Challenge, check out the first look at Saturday's forecast winds: > > https://earth.nullschool.net/#2021/05/08/1800Z/wind/isobaric/850hPa/orthographic=-104.64,39.77,5329 > > Any guesses where the best location to go birding will be? > > Ask questions, be curious, and keep the reports coming. Migration and > weather are slowly unravelling this year's mysteries of movement. > > Rambling email concluded. > > See ya in the field, > Bryan > > Bryan Guarente > Meteorologist/Instructional Designer > UCAR/The COMET Program > Boulder, CO > -- -- You received this message because you are subscribed to the Google Groups "Colorado Birds" group. To post to this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/cobirds?hl=en?hl=en * All posts should be signed with the poster's full name and city. Include bird species and location in the subject line when appropriate * Join Colorado Field Ornithologists https://cobirds.org/CFO/Membership/ --- You received this message because you are subscribed to the Google Groups "Colorado Birds" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. 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