What am I looking at? Book End Vortex?

[Shane Lee]

As I'm overseas in the military right now I am learning from today's severe weather outbreak vicariously from web resources. I like to look through radar loops to see tornado warned areas to try to decipher what I'm looking at and what caused the warning. I have read about book end vortices during linear storm events. I saw this one in Ohio today and wonder, is this what I'm looking at? Thanks in advance for your insights.

 

[rdale]

No, a book end would be on the end of the line. This is just an embedded rotation around the "kink" in the line.

 

[George Widener]

Hi Shane!
You can find a very good example of a bookend vortex at this link:
http://www.crh.noaa.gov/grb/events/061101.php

I lived through this storm, lost most of my trees and got a new roof. Very ugly!

 

[Greg Blumberg]

Just to let you know about your goal to find what caused warnings. Since the warning type is somewhat subjective in the Weather Forecast Offices, sometimes a tornado warning is not exactly for a tornado, but can be used for high wind events to warn others with the same "severity/urgency" of a tornado warning. It has been done before.

Also, the tornadoes that were appearing along the line would form and disappear very quickly, so some of the warnings were put in place because it was a precautionary thing based on past evidence of tornadic activity along the leading edge of the line.

 

[rdale]

Since the warning type is somewhat subjective in the Weather Forecast Offices, sometimes a tornado warning is not exactly for a tornado, but can be used for high wind events to warn others with the same "severity/urgency" of a tornado warning.

That's incorrect... Tornado Warnings are only issued when the forecaster think a tornado is occurring. If the threat involves high-end winds, they issue a SVR and put "enhanced" text in the product.

http://www.weather.gov/directives/sym/pd01005011curr.pdf

3.1 Mission Connection. Tornado Warnings (TORs) are issued to protect lives and property. WFO forecasters issue TORs to provide the public and emergency managers with advance notice of tornadoes.

3.2.2 Issuance Criteria. WFOs should issue TORs when there is radar or satellite indication and/or reliable reports of a tornado or developing tornado.

It has been done before.

If so, that was in error and goes against the NWS procedures (and common sense.) All that does is confuse people and harm the warning process.

 

[Skip Talbot]

Greg may be referring to those times when they will tornado warn an entire line. There were some warnings yesterday that spanned multiple counties, and probably a hundred north/south miles of squall line and embedded cells. As Rob pointed out, they aren't actually warning for straight line winds but using a tornado warning to get attention. I believe in these instances, tornadoes (especially brief/smaller ones) are possible at many points along the line at any given moment, so they just tornado warn the entire thing. The warning text probably says something along the lines of "a line of thunderstorms capable of producing a tornado...".

 

[rdale]

It was interesting watching that happen yesterday, as some offices issued SVRs and then would pop a TOR when appropriate covering a smaller area. I think that was a great idea.

Those that blanketed 4-8 counties at a time with TORs are guilty of a little overkill, but I think given the fact that everyone got at least "some" gusts out of the line means they don't really feel it was a false alarm.

 

[Nick Nolte]

It was interesting watching that happen yesterday, as some offices issued SVRs and then would pop a TOR when appropriate covering a smaller area. I think that was a great idea.

Those that blanketed 4-8 counties at a time with TORs are guilty of a little overkill, but I think given the fact that everyone got at least "some" gusts out of the line means they don't really feel it was a false alarm.

Yeah, I agree with that. Severe warn the line, then tor warn the areas that are most likely to produce spin-ups.

The effect at those locales that were tornado warned for the entire line is this: line passes, a few 60 mph wind gusts occurred, nothing out of the ordinary, everyone is going "wtf?"

 

[Shane Lee]

Hi Shane!
You can find a very good example of a bookend vortex at this link:
http://www.crh.noaa.gov/grb/events/061101.php

I lived through this storm, lost most of my trees and got a new roof. Very ugly!

Thanks a lot for the graphical example, George. I find that when I read something I can't get a great idea of the scale of it unless I find a good picture. This phenomena is on a lot larger scale than I had thought.

 

[Bob Hartig]

At one point during this past Tuesday's event, a tornado warning extended along a segment of the line in Michigan from slightly south of I-94 to slightly north of I-96. It struck me as the darndest thing, and I assumed that it was issued because GRR considered that section of the squall line to be capable of producing near-instantaneous spinups across a very broad swath.

 

[Bart_Comstock]

As stated above for it to be a BEV (bookend vortex) it would need to be at the end of the line. The BEV will typically take on a coma head like appearance on radar. As a bow echo surges out it causes two areas of rotation to form.If we look at the bow from above and consider the front of the bow the direction it is moving towards we can assign the ends of the bow echo as the right and left side. On the right side (typically the north in the northern hemisphere) you will get cyclonic rotation and on the left side you will get anticyclonic rotation.

Bellow you will find a graphical representation of the progression of how a bow echo would look on radar as it evolves. The non-bold "A" stands for anticyclonic and the non-bold "C" stands for cyclonic. Although there is a slim chance that the anticyclonic will become rooted, typically it is the cyclonic rotation that does and thus is the more likely of the two to produce a tornado.

The best way to picture how a BEV forms is to picture a person who is paddling a canoe. Picture the blade of their paddle pushing through the water. on either side of the paddle as it pushes through the water little eddies will form. Since the air behaves as a fluid the same principal happens with a bow echo.

If one where to try and chase this system they would find that more often than not the possible tornado will be unapproachable due to it being tightly wrapped in rain. Unfortunately, just as is the case with a LEWP (line echo wave pattern), these tornadoes tend to be very brief and nearly impossible to safely see through the rain.

Shane, the radar image you posted in your post looks like a typical LEWP, or line echo wave pattern. Bellow is a perfect example of what one would ideally look like on base reflectivity. The LEWP is located inside the tornado warning box. A LEWP, as Rdale mentioned, will typically look like a kink in the line.

Hopefully this helps you understand what is a bookend vortex, how they form, and how to spot one a bit better.

 

[George Widener]

Very informative post, thank you Bart!

 

[Bob Hartig]

Does anyone on this forum have any actual photos of bookend vortices? I've seen plenty of them on radar, but it seems to me that visually they'd be hard to instantly identify the way one can a mesocyclone associated with a supercell. The fact that they're filled with precip suggests that any features would necessarily be obscured, but beyond that, the structure is different, and I wonder what feautures a bookend vortex would exhibit if the rain could somehow be taken away.

I don't generally chase bow echoes, but I've nonetheless encountered my share of them. I can recall only one time when I saw something that made me think, "Hmmm...could be a bookend vortex."

 

[Bart_Comstock]

Does anyone on this forum have any actual photos of bookend vortices? I've seen plenty of them on radar, but it seems to me that visually they'd be hard to instantly identify the way one can a mesocyclone associated with a supercell. The fact that they're filled with precip suggests that any features would necessarily be obscured, but beyond that, the structure is different, and I wonder what feautures a bookend vortex would exhibit if the rain could somehow be taken away.

I don't generally chase bow echoes, but I've nonetheless encountered my share of them. I can recall only one time when I saw something that made me think, "Hmmm...could be a bookend vortex."

I'd imagine it would likely look like a HP supercell, really they are almost always wrapped with heavy precip so you wont find any photos of one. Like I said in my earlier post, just as with a LEWP, you really can't chase one and they are almost impossible to actually see due to the heavy precip associated with them.

 

[Tim Shriver]

"Since the warning type is somewhat subjective in the Weather Forecast Offices, sometimes a tornado warning is not exactly for a tornado, but can be used for high wind events to warn others with the same "severity/urgency" of a tornado warning. "

Not true and if your WFO is doing this then they need to be reported for not following the set guidelines for doing so. It is not subjective and well spelled out in the NWS protocols and guideline's.

A t-storm with high damaging winds will contain the words "Hurricane force winds"
if the winds reach that level. Anything less then that but above 58 mph is just a severe t-storm warning.

To abuse tornado warnings is not wise and should not be allowed to occur.

rdale said "It was interesting watching that happen yesterday, as some offices issued SVRs and then would pop a TOR when appropriate covering a smaller area. I think that was a great idea"

I agree with his statement. (shocking ain't it) but he is very correct on this.

Tim