Tornadoes with Tentacle Like External Vortices!!

[Bill Tabor]

As for all the external vortices. I'll put it into terms that I understand. Seems to me the air accelerating in so incredibly fast at ground level, and then spiraling up into the tornado causes the horizontal rolls... just like at the back side edge of a paddle through water. Seems logical to me the most violent tornadoes would have these... cause the rolls get tight enough, intense enough to become visible with condensation. What I'm describing is probably the same thing as the smoke ring effect Dan mentioned.

Yeah, I think you guys may be on to something there. Plus during the 'Tuscaloosa' outbreak day I remember watching mesoanalysis loop of 850-250mb Diff. Divergence which tracked right along with the violent outbreak cells. Seems like a large scale wave of lift was just sucking air from below. Perhaps those vortices are evidence of such large scale massive lift.

 

[Neal Wikner]

At the Minnesota Storm Chasing convention this year Kinney Adams of Tempest Tours had a presentation on the Keister, MN tornado of June 17, 2010. His presentation was all about the vorticity and his video had a great examples of this phonomenon as well. He called them 'vorticity noodles'. Don't recall any explanation of their creation though.

 

[Greg Blumberg]

The theory that I heard recently is that it's a combination of the multi-vortex nature of the tornado and the strong wind speeds literally tilting the sub-vortices into a horizontal direction. Thus I guess that it's a good sign of the violent nature of the tornado.

The problem with the tornado (from the theories) is that it's not formed by tilting of vortex lines into the vertical from the horizontal, but rather the vortex is being built by stretching and other different processes. If you tilt vorticity, you don't generate a circulation at the ground.

 

[Dave Kaplow]

The Cullman Tornado had even more impressive horizontal fingers than Tuscaloosa, starting at around the 4:45 mark on this tower cam video. They seem to be found on many of the violent tornados from the 27th. At a guess, I'd say you need strong vertical motion to generate them. The actual physics behind these things is probably pretty chaotic.

 

[J Tyler]

Last fall, my wife and I followed a HUGE wall cloud in Texas that had multiple (5-6) thin to moderate funnels that kept spinning up out the SIDES of the wall cloud, reaching outward. It was very dramatic to see. The wall cloud only produced two quick tornadoes that reached the ground, both of which were small and short lived. The whole thing looked more like "Medusa" moving across the sky. Of course, I didn't have the video camera rolling during the most obvious part of the event, but here is the wall cloud I'm talking about:

Watch video >

Totally off subject, but the discussion in the video was because we had placed ourselves between two areas of rotation (one in front of us, the big wall cloud, and a newly forming wall cloud to our 3 o clock), and we were trying to keep position on both of them, but hail was coming...

 

[Donovan Gruner]

My guess after watching several videos would be a combination of the violent upward motion creating some sort of horizontal rolls, and stretching of horizontal vorticity by the intense inflow of air getting sucked violently into the vortex. Generally, I believe tornadoes are thought to pull most of the air into the vortex near the surface, but maybe with some of the more violent examples, the pressure falls and violent upward motion become strong enough to the point where the vortex begins pulling more air in from the sides. Imagine hooking a vacuum up to some sort of brittle tube, and then impeding the flow of air into the base of the tube... the vacuum would likely break a hole in the side of the tube in an attempt to fill the void created by the vacuum. So maybe the pressure falls are so great in some of these examples that the vortex needs to pull more air in horizontally at different levels to attempt to equalize the pressure inside the vortex to that of the pressure outside the vortex. But as for the Cullman tornado, I have never seen anything like that. That is absolutely stunning!

 

[Jeff Duda]

The Cullman Tornado had even more impressive horizontal fingers than Tuscaloosa, starting at around the 4:45 mark on this tower cam video. They seem to be found on many of the violent tornados from the 27th. At a guess, I'd say you need strong vertical motion to generate them. The actual physics behind these things is probably pretty chaotic.

This kind of behavior is probably due to a phenomenon called vortex breakdown. There are a number of articles in the fluid dynamics world on this phenomenon. One such article in the Bulletin of the AMS is here.

 

[Skip Talbot]

I saw some of this going on with the Albert Lea, MN EF4 from June 17, 2010 as others have already mentioned in the thread. My take on the winds that might have been at play during the time with the RFD and inflow's vertical interactions creating strong horizontal vorticity:

Jesse Risley has a nice zoomed shot of the tornado a few minutes earlier and you can see tentacles within the main circulation.

These tentacles definitely need a subset of ingredients that not all tornadoes possess. I don't recall seeing any with the Bowdle, EF4. I'm guessing the inflow needs to be near saturation and there need to be a lot of small scale areas of rapidly rising and rapidly descending winds in close proximity as opposed to one dominant updraft and one dominant RFD.

 

[DRMabe]

A still from my video of the Tuscaloosa Tornado showing the Horizontal Vorticity

 

[Robert Edmonds]

I should go back to my simulations from earlier this year http://bit.ly/jjx9d9. Most of these tentacle vorticies wrap counter-clockwise with height around the main vortex. If you consider just a line vortex of this nature (wrapping in this manner), it should produce vertical velocity upwards. This would carry the line vorticity upwards (as it appears most of them do), with no stretching needed (assuming cyclonic rotation). If it was to wrap clockwise with height and still be cyclonic, the vertical velocity would be downward, and would carry the vortex lines downward too (but I don't see many with these attributes).

 

[Melissa Jablonski]

I've seen them. Palm sunday 1965 in Elkhart Indiana.Interesting thing I remember was the tentacle that was way too close to me was hissing.

 

[Dave Gallaher]

Well, the Weather Channel dubbed these 'mustache tornadoes' in their feature on the outbreak. I hope it doesn't stick.

 

[Dave Kaplow]

Here's another view of the Cullman tornado I found on Youtube. Pretty spectacular.

But... Mustache tornadoes?!? Hell no, there's got to be a better name than that. Agreed, this cannot stick!

 

[Dave Gallaher]

Here's another view of the Cullman tornado I found on Youtube. Pretty spectacular.

But... Mustache tornadoes?!? Hell no, there's got to be a better name than that. Agreed, this cannot stick!

Yep--tentacle is a better term to me. BTW, that last Cullman vid has some great footage, but unless you kill the volume you're stuck with a Saliva track.

As the power is coming back on, there will be a lot of phone videos uploaded over the next few days.

 

[Andy Wehrle]

I haven't seen this one mentioned in here, yet. A classic in the realm of horizontal vorticies:

http://www.youtube.com/watch?v=TUq7TTRXDSc