Tornado or Funnel?

Aug 9, 2012
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I'm stuck on whether this funnel cloud appears to be on the ground as a tornado. I shot this on October 9th outside Cedar Rapids Iowa. There was a velocity couplet before this storm formed a funnel cloud that appeared high based but upon editing there appears to be some spin up underneath it. Was looking for other opinions. Thanks!

Edit: I do not have video from this partiicular vantage point, I was shooting photos as it caught me off guard somewhat.
 

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Tyler Burton

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I'm stuck on whether this funnel cloud appears to be on the ground as a tornado. I shot this on October 9th outside Cedar Rapids Iowa. There was a velocity couplet before this storm formed a funnel cloud that appeared high based but upon editing there appears to be some spin up underneath it. Was looking for other opinions. Thanks!

Edit: I do not have video from this partiicular vantage point, I was shooting photos as it caught me off guard somewhat.
Hi, Ethan. I’m pretty sure that at the moment that photo was taken, you’re looking at a funnel cloud. I don’t see any dirt or debris getting kicked up at the bottom, plus do you see how the funnel has those scud clouds hanging off of it, and how the clouds around it are just kinda loose and not very compact? Well, that might be sign that the updraft is going through a rough time. So no debris at the bottom combined with the looks of the updraft base makes me think that it’s just a funnel cloud.
 
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Mar 8, 2016
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I've seen tornadoes with smaller funnels personally, but without being up close enough to observe any potential ground circulation as is the case with that image, I would just go with funnel.
 
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Nov 13, 2017
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Generally speaking, we're the ones defining whether something is a tornado or funnel - nature doesn't really care about the distinction - so it's not a tornado unless someone has clear evidence that it was a tornado. If there was no survey and you can't actually pinpoint a ground circulation, I would use caution calling it a tornado.

As for whether or not I think that that was ever on the ground (very subjective viewpoint here), more often than not in my experience a funnel extending downward out of the cloud base likely stirred up something on the ground, even if for just a moment. There is no scientific basis for that thought, though.
 
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Aug 9, 2012
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I definitely agree. I was just looking for others opinion. I think it was just a funnel, but I thought it would be a good discussion. Excuse my grammar. I broke my arm this week and its my right hand, so I am having a hard time typing.

I appreciate everyone's input on this.

For the record, I wasn't claiming this as a tornado. Just questioning its validity as a tornado vs being a funnel.
 

Dan Robinson

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I think this most likely had something capable of damage on the ground underneath. Right now the NWS wouldn't count it as they are still in the "funnel to ground or some visual of debris" requirement. I think the recent paper about tornadoes developing ground-up might put a rest to any speculation about these in the future.
 
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rdale

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I think the recent paper about tornadoes developing ground-up might put a rest to any speculation about these in the future.
Don't overinterpret that :) The paper is not saying that all tornadoes form from the ground. That's pretty obvious from cases where funnels are aloft and never cause damage at the surface.
 
I think the recent paper about tornadoes developing ground-up might put a rest to any speculation about these in the future.
I've seen this work presented a couple times now. I think that all tornadoes forming in this manner is possible, especially if observations support it. However, as a scientist, it irks me somewhat to hear see the authors' conclusion that all tornadoes form this way based on a handful of observations when roughly 1,000 tornadoes occur every year. I'm not saying the work is flawed or the results are impossible. There just needs to be more tests and/or observations to make sure that is 100% the case before saying so.

Supercell and tornado simulations are providing some great data on what goes on during tornadogenesis. These simulations show that there are numerous vortices that form along various boundaries (RFD and FFD) under the supercell that get drawn toward the meso. It's when the low-level meso can stretch one of these vortices enough do you get a tornado. So yes, the example provided by the OP could have a circulation on the ground, but possibly the vortex was not stretched enough to become visually tornadic. However, by the AMS definition of a tornado, that would mean this example could be a tornado.

The NWS needs ground truth (pun intended) that a tornado did occur. This is done by observing visual damage or through photographic evidence of ground circulation. So if OP's example is tornadic based on the AMS definition, but there was no evidence of a ground circulation whatsoever, most likely because the circulation was too weak, then no, the NWS is not going to count it. This is why there has been unofficial talk recently on what actually constitutes a tornadic circulation. The atmosphere underneath a supercell is extremely chaotic and has numerous eddies and vortices. The science needs to be vetted before every funnel cloud and weak circulation is considered a tornadic circulation.
 
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rdale

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...and to add on, they aren't saying that you can't have funnels aloft because tornadoes form on the ground first. Just that those tornadoes formed near the surface. In either event, the circulation exists aloft long before the tornado starts, and the public couldn't care less - if there is damage on the ground it's a tornado, if not it wasn't.
 
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So yes, the example provided by the OP could have a circulation on the ground, but possibly the vortex was not stretched enough to become visually tornadic..

Alex your commentary was very interesting but I am having trouble understanding the part that I excerpted above: I certainly understand that there is not always visible condensation, but if there is circulation on the ground, the tornado formed on the ground first (per the subject of your commentary) AND there is a funnel above, then how could it be that “the vortex was not stretched enough”? Wouldn’t having a circulation both on the ground and up above indicate that it was indeed stretched enough, and it’s simply lacking condensation all the way between cloud and ground?
 
Alex your commentary was very interesting but I am having trouble understanding the part that I excerpted above: I certainly understand that there is not always visible condensation, but if there is circulation on the ground, the tornado formed on the ground first (per the subject of your commentary) AND there is a funnel above, then how could it be that “the vortex was not stretched enough”? Wouldn’t having a circulation both on the ground and up above indicate that it was indeed stretched enough, and it’s simply lacking condensation all the way between cloud and ground?
You're right, but I also said "... stretched enough to become visually tornadic", i.e., complete condensation funnel and/or debris or dirt being vigorously lofted at the surface that provides visual truth that the circulation does exist. There are other reasons as to why a vortex may not be visually tornadic, and this is just one of them. I'm also bouncing between the official AMS definition of a tornado and what the NWS considers a tornado. This is not to say there is a disagreement between the two sources, it's just that the NWS needs visual proof of a ground circulation. This could change if the previously mentioned research and additional studies eventually come to find that if there is evidence of a vortex at the cloud base (e.g., a funnel cloud), then there is a circulation extending to the surface.
 
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Dan Robinson

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This may be a very interesting area of research that to my knowledge has never been done in detail. The hypothesis is that most, if not all, "tornado sized" funnels below cloud base (that is, not "shear funnels", midlevel funnels or other small transient features) have a damage-capable circulation at ground level given moderate-or-lower LCLs. That is, it would be more accurate to assume they are tornadoes than not, for all practical purposes.

A damage-capable circulation will only manifest itself to an observer at distances greater than a half-mile or so if there is enough material to loft (dirt or debris). Without anything to loft (such as over a rain-soaked field), the circulation at ground level will present at minimum with lighter debris and periodic small suction vortices. To gain a positive visual of these features, you quite literally have to be right there next to it. A spotter a half-mile away or farther will never see these, but we know they are likely there as a result of dozens of chasers making close intercepts of them.

The primary evidence to support this hypothesis comes from chasers who have witnessed and documented quite a few of these. How many times have chasers been right under a funnel and it's been observed with certainty that there *hasn't* been something at ground level? I can't think of any.

The best example I have with good video documentation is the Meredosia, IL tornado on 12/1, with emphasis on the ground-level circulation crossing the road on my front dashcam at 3:03 in the video. One of the suction vortices was no bigger than 10 or 15 feet above the ground:


I think that most funnels (again, "tornado sized", not small transient features) have *at least* something similar underneath, and I believe this might be confirmed by research if it were undertaken. A mobile home or weaker structure would be damaged or even destroyed if hit directly by such an innocuous-looking circulation, so the paradigm of always dismissing them as non-tornadic has real-world implications.

We might have 50 to 100 case studies for a paper just from chaser observations. I have at least a half dozen myself.
 
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rdale

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Good stuff Dan... The primary tool to rebut that hypotheses is the lack of any signs of damage underneath the areas the funnel traveled over. If the winds were strong enough to destroy a mobile home, there'd be SOME evidence at the ground.

But I strongly disagree with your "real world implications." I can't see any it. It provides for good discussions like this, but these discussions don't impact the "real world."
 
Apr 23, 2016
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Don't overinterpret that :) The paper is not saying that all tornadoes form from the ground. That's pretty obvious from cases where funnels are aloft and never cause damage at the surface.
Exactly. It seems evident to me both logically and from experience that there are multiple different ways to achieve tornadogenesis. I don't think its strictly from the ground up or from the top down, I think it varies on a case by case basis.
 

Jeff Duda

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What this really boils down to is the fundamental minimum vortex strength to distinguish a tornado from non-tornadic vortices.

What is a tornado? It is only officially defined qualitatively as

AMS Glossary said:
A rotating column of air, in contact with the surface, pendant from a cumuliform cloud, and often visible as a funnel cloud and/or circulating debris/dust at the ground.
So...all we need is a rotating column of air in contact with the surface? Check out any number of papers that perform simulations of tornado-like vortices from very high resolution models. Here are a few to whet your appetite:
Schenkman et al. (2012)
Schenkman et al. (2014)
Xue et al. (2014)
Roberts et al. (2016)
Lee et al. (1997)

I'll save you the effort by summarizing what they all show - there is some magnitude of vortex (closed, roughly circular vorticity contours exceeding some background value) present in advance of official tornadogenesis in all of these cases. So that means we have a rotating column (btw, what defines "column" here? how much vertical extent is needed before a rotating blob of air is considered a column rather than strictly two-dimensional? that is an issue I will not further cover) of air attached to a cumuliform cloud...isn't that a tornado then?

Well, no...because someone probably wouldn't classify such a vortex that might only be producing, for example, 35-mph surface winds, as a tornado. If you disagree, tell me what the wind speed range of EF0 tornadoes is. The answer: it bottoms out at 65 mph. Why did the architects of the EF scale decide to restrict EF0 to >65 mph wind speeds? I don't know, but I suspect it has to do with the fundamental issue (repeated from the top) - the minimum strength to regard a vortex as "tornado strength".

My previous comment was based on the above criterion. But is that immutable? Of course not. But with an issue like this, some sort of quantitative threshold will need to be implemented to separate tornado-strength from sub-tornado-strength vortices.
 

rdale

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Good stuff Jeff. The 65mph number is likely going to be modified with the new EF-scale. After it was implemented, it became very obvious that this was written by a group centered in TX/OK :) Michigan tornadoes can easily be under 65mph, which is probably a reason the F-scale did NOT have a lower bound. In any event, I've not heard an exact number but the 65mph (which is already ignored) should be getting a tweak.
 
But with an issue like this, some sort of quantitative threshold will need to be implemented to separate tornado-strength from sub-tornado-strength vortices.
That was an excellent scientific summary of the topic, Jeff. I pulled the above quote because I feel this should be one of the main takeaways from this discussion. As has been discussed in other threads, what defines a tornado and how we rate them needs to be adjusted. Deciding what is and is not a tornado is far more than just a count. It has far-reaching scientific implications that need to be considered by experts and researchers when coming up with criteria. Until this is addressed, don't expect the NWS to count every funnel as a tornado.
 
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To clarify your last line Alex - the NWS will NEVER classify a funnel as a tornado. If there is no circulation or damage on the ground, it's not a tornado.
In the eyes of the NWS, exactly. I was addressing the possibility of, based on the "ground-up" research discussed prior, the chasing community and others challenging the NWS to verify every funnel as a tornado when there is no definite evidence of anything occurring at the surface. I've already seen this happen and the research has only been made widely known as of a few weeks ago.
 

Dan Robinson

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The point is that it can probably be established that most funnels *are* tornadoes. Absent research to prove it, I wouldn't expect the NWS or the meteorology community to accept the new paradigm.