Expanding ring on radar

Joshua Nall

Joshua Nall

EF4
Joined
Feb 27, 2009
Messages
463
Location
Texarkana, AR
This morning, July 13th, on the Shreveport, LA radar-KSHV, starting at about 6:15 local time... three separate low intensity blob returns appear and quickly spread out forming well defined rings. I noticed this yesterday morning as well, though I can't remember if it was the same time, and places. Does anyone have a guess as to what is being picked up here? It looks very similar to the radar returns I have seen of bats leaving caves in south, TX. I'm pretty sure there are no large concentrations of bats around here to be causing that. This morning one is very near Tyler, TX, another is just north of Shreveport, LA. The third one is near Walters, LA. It could be that it is a somewhat common occurrence, but I have never noticed it before.

Josh
 
Bart_Comstock said:
My guess is that you are looking at birds or or insects taking flight after awaking in the morning. Do you maybe have a few screen shots of said blobs?
Click to expand...

Yep, it's the time of the day when flocks of birds depart where they nested for the night and go back out searching for food etc.
 
This image is at 6:15 and clearly show the three rings just after they form, the one on the left near Tyler, TX appeared as a perfect complete expanding ring for a few scans.

expandingrings.png


Below is a close up of the far right ring near Walters, LA just 30 minutes later. It has expanded in size 4 or 5 times and become more defined, except for the Western part.

expandingring.png


I had read about birds causing this, but never seen it before. I assumed that they would not spread out nearly as fast, or the ring of birds get this big. Also after I mentioned bats I realized that they take flight at dusk. It would be interesting to go to this spot at dawn, if it is a daily thing, make a visual on this as to what kind of bird, how many, etc...

Josh
 
Last edited by a moderator:
I'm pretty sure those are bats: http://www.spc.noaa.gov/coolimg/
Click to expand...

The blobs that transitioned into expanding rings first appeared at dawn this morning on radar, so it can't be bats as bats take flight at dusk every evening. I'm really interested now in finding out what kind of birds? these are and why they would be congregating at these specific sights to roost.
 
That's one massive flock if that's birds/bats or a very very tiny county.
 
Very possibly caused by a few descending air parsels after sunrise. Humidity causing radar beam to hug the ground, so the radar beam can easily pick up insects that are in the ring of ascending air rising around the edges of the 'sort of' downdraft. Thats my guess.

Tony
 
I would just about bet that you have a colony of Egrets (large white birds quite common in Texas and Louisiana.)

This is the time of year that the nesting is done and the colonies are at their largest. Egrets form large colonies that can become a nuisance, and even a health hazard (don't park your car under the trees).

Like Bats they leave en masse and return at about the same time but not in the same large grouping. You can probably see some of the returns if you watch the location at or near sundown.
 
Very possibly caused by a few descending air parsels after sunrise. Humidity causing radar beam to hug the ground, so the radar beam can easily pick up insects that are in the ring of ascending air rising around the edges of the 'sort of' downdraft. Thats my guess.
Click to expand...

That's certainly what it looks like, just like an outflow boundary from a thunderstorm, but I'm not sure you can have descending air parcels this localized and intense in the absence of a thunderstorm. I did some figuring and it appears that the rings expanded at around 30 miles per hour. That would mean that you would have had to have surface winds of near that in these areas, right? I'm pretty sure that did not happen.

It must have been birds, Egrets maybe, since they nest together... and there are plenty around here. Even if the birds were spaced out pretty well that would be a lot of birds in that ring, we are talking about a diameter of 30 to 50 miles at the largest when the radar was still picking them up. It's hard to imagine a flock of birds equally dispersing in all directions like that also, but that must be what caused it.
 
Same three rings showed up this morning as well. Just for the heck of it here are a couple of radar scans from the Tyler, TX area this morning. First one just after it first appeared and the next a few scans later. Looks to be a daily thing for now anyway, and in the same spot each morning. If it's birds then they are returning to the same spot every night. Wish I knew someone that lived near there, see if they could poke their head out at dawn and see anything :)

expandingrings17-15-09.png


expandingrings37-15-09.png
 
Tyler has been experiencing extreme dry heat. When cool moist air aloft come in contact with the hot rising air it triggers very violent thunderstorms. There's a good chance you may see some tomorrow morning as well.
 
Kirk Chestnut said:
Tyler has been experiencing extreme dry heat. When cool moist air aloft come in contact with the hot rising air it triggers very violent thunderstorms. There's a good chance you may see some tomorrow morning as well.
Click to expand...

?

The radar returns on that are nowhere near strong thunderstorms. :rolleyes:

Returns he's experiencing are like everybody else said, most likely birds/insects of some sort.
 
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