Suction vortices

[Tomas Pucik]

I was trying hard to search the internet, though I have not found much literature on how are suction vorticess created and sustained within a tornadic circulation. Their formation seems to be related to process called vortex breakdown and depends mostly on swirl ration ( what is this?) and complexity of terrain over which tornado is passing. Do you have any more information on this topic? Or is there any good literature/papers that would cover this problem?
Thanks for responses

 

[Willie Dines]

Hey Thomas, how are you?

I am beginning to believe that suction vortices are a part of the life cycle of quite alot of tornadoes, mostly at the stage of when they have just touched down, as this still give the possiblity of any breakdown bubbles, to travel down the funnel, where internal downdrafts can come out under (or through) the base of the funnel, depending on the intensity of the rotaion and width of the funnel itself

Suction vortices aren't necessarily resticted to being in a vertical manner, they can come out of a large tornado horizontally, (May 3rd '99 F5 being the prime example of that) as well as smaller tornadoes, but this is a rarity.

Swirl ratio, is something that I simply haven't looked into at all, as I never looked to use that data when I was operating the tornado machine I had, but to my understanding of it, the swirl ratio would be more or less how flat or acute the angle, to the side of the funnel, that the inflow jets would the drawn in from, but I believe that angle of updraft plays a part in this also, but I'm not sure because this is only my take on it, because I haven't been interested in looking to read up on all the scientific terminology, but I'm here to live and learn

I'm not aware of any papers/studies on suction vorticies as I simply haven't been on the look out for them, but I suspect that the late Ted Fujita, or else Howard Bluestien, Josh Wurman, Chuck Dowsell, Erik Rasmussen, or some of the other well known legends out there would be able to point you in the direction of any studies made on suction vrtices

I do know that Dr John T Snow, once turned a science lab into a 10ft tornado machine at one time, and he was able to reproduce some excellent multi-vortex tornadoes, in fact, he had recorded some of the experiments on microfilm, but I asked John about these clips and he said that the microfilm would be too delacate to try and transfer to any other format now, which is a pitty, but it would be worth sending him an e-mail if you get the chance and see if he may be able to help you

I don't know if this is of any help or not, but I wish you the best of luck reguardless

Willie

 

[Donald Rosenfeld]

Hi Thomas

Re Swirl Ratio, take a look at:

http://ams.allenpress.com/archive/1520-0469/57/4/pdf/i1520-0469-57-4-527.pdf

 

[Gene Moore]

This reminds me of the tornado cyclone thread also in progress. Another term that I believe is somewhat useful, but not heard so much these days. Suction spots, made popular by Fujita in his Lubbock tornado damage assessment paper has been around for 35+ years.

Reference:
http://www.srh.noaa.gov/lub/events/1970/19700511/index.php

Photo justification of suction spots:
http://www.srh.noaa.gov/lub/images/events/1970/19700511/aerial_suction_swaths.jpg

As for the thread comment about suction spots are a phase most tornadoes go through....I would like to add one to that. It's that many tornadoes have this feature, suction spots or sub-vortices and we can't see them. They are buried within the funnel wall or obscured by dirt and or debris. That's not to say all tornadoes have them, but evidence from damage paths appear to support they are there more often than we are visually observing them. There are some cases where they become almost as large as the main parent vortex with 2-3 huge vortices rotating about each other. Reports from people that witness large tornadoes often say "two or three tornadoes came together to form one large funnel....." This is often the result of someone with an untrained weather eye trying to describe what suction spots look like.

As for the term, although its got some history I prefer sub-vortex and that's what I see most often in more recent publications.

Gene Moore

 

[Justin E. Reed]

That is very true, large suction spots. If you look at the video footage taken north of Andover, KS, you can see very massive vorticies. Just before it enters town and zooms in to the large homes, it reveals a small, split-second hole, showing one large vortex on the right, and 1 or 2 on the left. This is also evident that as it moves, it appears to expand and contract, essentially breathing, that, my guess, would be the 2 large, and possibly only vorticies rotating around the common center. It also shows this as it passes through a clearing in the trees west of town, just after it passes by the Terradyne Country Club building, I counted 4 vorticies rotating around, I think some merged to make the larger ones I mentioned above. Very interesting video, kinda like a peep show( figurative speech), it'll give you a quick show, and then hide them again in a second. That tornado is still the one tornado I continue to research like a mad man, just can't get enough info or video of it. If any one can help me out, greatly appreciate it.

 

[ELY M.]

the urls in your post are broken. I know NWS have redone their website.

I find the new urls again.

http://www.srh.noaa.gov/lub/?n=events-1970-19700511

http://www.srh.noaa.gov/images/lub/events/1970/19700511/aerial_suction_swaths.jpg

This reminds me of the tornado cyclone thread also in progress. Another term that I believe is somewhat useful, but not heard so much these days. Suction spots, made popular by Fujita in his Lubbock tornado damage assessment paper has been around for 35+ years.

Reference:
http://www.srh.noaa.gov/lub/events/1970/19700511/index.php

Photo justification of suction spots:
http://www.srh.noaa.gov/lub/images/events/1970/19700511/aerial_suction_swaths.jpg

As for the thread comment about suction spots are a phase most tornadoes go through....I would like to add one to that. It's that many tornadoes have this feature, suction spots or sub-vortices and we can't see them. They are buried within the funnel wall or obscured by dirt and or debris. That's not to say all tornadoes have them, but evidence from damage paths appear to support they are there more often than we are visually observing them. There are some cases where they become almost as large as the main parent vortex with 2-3 huge vortices rotating about each other. Reports from people that witness large tornadoes often say "two or three tornadoes came together to form one large funnel....." This is often the result of someone with an untrained weather eye trying to describe what suction spots look like.

As for the term, although its got some history I prefer sub-vortex and that's what I see most often in more recent publications.

Gene Moore

 

[Greg McLaughlin]

I am working on an illustration of how a tornado with the nw Oklahoma supercell on April 14th developed suction vorticies. As for the tornado cyclone, this is something I have learned much more about after this past year. The sunset tornado southwest of Russell, KS on May 25th is the best observation I have had yet of the development of the tornado cyclone within a low-level mesocyclone. Along with that, I have video evidence that appears to support some of the latest ideas when it comes to tilting horizontal vorticity into the vertical. It just takes time to put all of this together into some sort of media format.

 

[Shane Adams]

Probably the best example of a Tornado Cyclone I've ever seen personally was near Conway Springs, KS on the evening of May 29, 2004, just before dusk. In fact, during the video I remarked about stories Gene Moore had posted in the past about them, and how it was amazing to finally be seeing what he was talking about. Tornadoes are of course hard to exactly predict, but I have seen many cases where a sustained Tornado Cyclone often precedes a strong/violent tornado. That "carousel" look is a red flag for imminent incredible tornadic action.

On the topic of multiple vortex tornadoes/sub-vortices, I believe all tornadoes display some type of multi-vortex behavior at some point in their life cycle. Just watching videos of tornadoes, seeing them personally, and also the several dust devils I've observed, they all seem to indicate at least marginal instances of "vortex breakdown" or multiple-vortex phase.