Signs of a tornado being "violent"?

[ChristofferB]

I have seen thousands of videos of tornadoes and somethings that strikes me from time to time is the use of the word "violent" about a tornado. Obviously, this is a highly relative term since all tornadoes are violent in their nature but let's talk about them in terms of Violent and Less Violent. I guess the definition of Violent in terms of tornadoes must be the maximum wind speed.

The video that led me to think about it again was this one:

The tornado never hits him but I would guess this is a Less Violent tornado (otherwise he would have been in much bigger problems). It suprised me since it was rather big. As far as I understand size is not directly related to how violent a tornado is.

This leads me to the following questions:

- What would be signs of a tornado being Violent? I have read horizontal vortices would be one sign, for example.

- I anticipate responses like "look at the rotation and wind speed" but to me all tornadoes look violent. It would be helpful to see an example of both a Violent and Less Violent in that case.

- is size at all related to wind speeds and how Violent a tornado is?

- As far as I understand the strongest tornadoes (most Violent ones) have sub vorteces which, I assume, are difficult to see after it has formed. Looking at the El Reno footage one can see them during the shaping of that tornado - and, apparently, there were sub vortices in that one. Are sub vorteces a key feature of a Violent tornado.

I am asking out of curiousity but also considering safety while chasing. It would be good to know when to stay far away and when it is "safer" to be at a reasonable distance..

 

[Andy Berrington]

I personally have developed a sort of criteria in terms of visual cues (not really quantifiable in any way) that I usually look for when determining the overall intensity of a tornado. One, as you mentioned, is horizontal vortices, which generally indicate an extreme amount of horizontal vorticity being ingested into a storm/updraft and thus most likely a stronger tornado.

On top of that, size of lofted debris, the height of the lofted debris and just overall horizontal and vertical motions near the ground level, in the wall cloud and within the funnel itself would be the other signs that a tornado is becoming intense. Violent tornadoes often have a very loud and distinct roar that tends to exceed the noise produced by weaker tornadoes (as you would expect).

As for the Rochelle tornado there, that was an EF4 (and a high end one at that, although it may have not been quite at that strength when it crossed I-39). That guy probably was feet away from his car getting lofted/rolled and sustaining serious injury if not becoming a fatality.

 

[Nick Wilkes]

I too, like Andy have some criteria.

1. The rotation. For example watch videos of Tuscaloosa and Andover. They have what I consider "violent rotation".

2. Horizontal vortices. This is something that only violent tornado produce, I have not seen any tornadoes other than F4 and F5 produce these. (If you know of any weaker tornadoes producing these, please let me know).

Damage:

When looking at the damage there's things violent tornadoes do that weaker ones don't (obviously)

Sometimes when looking at weaker damage with some shingles pulled off of rooms, trees down, and windows broken, I could be hard to determine between EF0 or EF1. Even a EF1 tornado can push a "slider home" off its foundation. But when you look at the damage of the stronger tornadoes, it becomes clear what is "violent".

1. Ground and pavement scouring. Such as Philadelphia MS and Jarrell TX, they produce what is arguably the most intense ground/pavement scouring ever caused by a tornado.

2. Shredded or severely mangled cars. An EF0 can flip a car. But what an EF5 tornado does to car is just incredible. Such as the 2011 El Reno tornado, and the 1999 more tornado. Cars were shredded! Joplin didn't shred card, but some of the cars where rolled up into balls of metal.

3. Well built homes totally swept away, with the debris finely granulated. Like I said above a 100MPH EF1 can sweep a "slider" home away. But when you have large, well built homes and mansions that in some cases were built to be tornado proof that were swept away leaving nothing on their foundation and the debris was finely granulated and wind-rowed and deposited miles away, you definitely have a violent tornado. Often with this, large furniture and appliances are shredded and can't be found.

For example in the 2011 Chickasha EF4 (though many including myself believe it was a EF5) a large "tornado proof" home was swept away, and even had some of tile flooring pulled of the foundation. And in Parkersburg, a newly built home was totally swept away, and it's walk out basement walls were destroyed, the debris left from that house was no bigger than mulch.

4. If the tornado does something "incredible" I'd classify it as "violent" but usually tornadoes that do something incredible tend to the things I have listed above. The Wheatland PA F5 swept away the Wheatland Sheet and Tube company, but what if to the Sheet and Tubes parking lot is something that's consider incredible. Pavement was scoured from the parking lot, the parks of the parking lot that weren't scoured had paper wedged under them! And during the 2011 Super-outbreak, I can't think of the tornado off the top of my head but it was on of the EF5 in Alabama, I believe either Smithville/Hackleburg or Rainsville, an underground storm shelter had all of the top soil blown off it and it was partially pulled out of the ground!

So that's how I classify if a tornado is violent, based on the rotation, horizontal vortices, and based on certain damage they do.


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[Brad Dormer]

I too, like Andy have some criteria.

1. The rotation. For example watch videos of Tuscaloosa and Andover. They have what I consider "violent rotation".

2. Horizontal vortices. This is something that only violent tornado produce, I have not seen any tornadoes other than F4 and F5 produce these. (If you know of any weaker tornadoes producing these, please let me know).

Damage:

When looking at the damage there's things violent tornadoes do that weaker ones don't (obviously)

Sometimes when looking at weaker damage with some shingles pulled off of rooms, trees down, and windows broken, I could be hard to determine between EF0 or EF1. Even a EF1 tornado can push a "slider home" off its foundation. But when you look at the damage of the stronger tornadoes, it becomes clear what is "violent".

1. Ground and pavement scouring. Such as Philadelphia MS and Jarrell TX, they produce what is arguably the most intense ground/pavement scouring ever caused by a tornado.

2. Shredded or severely mangled cars. An EF0 can flip a car. But what an EF5 tornado does to car is just incredible. Such as the 2011 El Reno tornado, and the 1999 more tornado. Cars were shredded! Joplin didn't shred card, but some of the cars where rolled up into balls of metal.

3. Well built homes totally swept away, with the debris finely granulated. Like I said above a 100MPH EF1 can sweep a "slider" home away. But when you have large, well built homes and mansions that in some cases were built to be tornado proof that were swept away leaving nothing on their foundation and the debris was finely granulated and wind-rowed and deposited miles away, you definitely have a violent tornado. Often with this, large furniture and appliances are shredded and can't be found.

For example in the 2011 Chickasha EF4 (though many including myself believe it was a EF5) a large "tornado proof" home was swept away, and even had some of tile flooring pulled of the foundation. And in Parkersburg, a newly built home was totally swept away, and it's walk out basement walls were destroyed, the debris left from that house was no bigger than mulch.

4. If the tornado does something "incredible" I'd classify it as "violent" but usually tornadoes that do something incredible tend to the things I have listed above. The Wheatland PA F5 swept away the Wheatland Sheet and Tube company, but what if to the Sheet and Tubes parking lot is something that's consider incredible. Pavement was scoured from the parking lot, the parks of the parking lot that weren't scoured had paper wedged under them! And during the 2011 Super-outbreak, I can't think of the tornado off the top of my head but it was on of the EF5 in Alabama, I believe either Smithville/Hackleburg or Rainsville, an underground storm shelter had all of the top soil blown off it and it was partially pulled out of the ground!

So that's how I classify if a tornado is violent, based on the rotation, horizontal vortices, and based on certain damage they do.


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EF-0s can blow sheds with lots of things in them across the street and into the neighbors yard as well! Found that out for myself in 2004...

 

[Mike Marz]

In my opinion, the following videos all show signs that a tornado is "violent".

Obviously there are hundreds of great video examples of violent tornadoes out there, but these 3 are fairly recent, high-quality, and all contain great violent tornado observations... the waterfall/jet sound, especially with headphones, the clear horizontal vortices in the Twistex video, and the absolutely astonishing, both vertical, and horizontal motion, with the Oklahoma drill bit. Also, there are two other links I've included at the bottom. One is another great example of violent tornadic acoustics taken by @Dan Robinson from the Bennington tornado, and the other shows the type and size of debris that violent tornadoes can loft into the air, as Andy mentioned.

http://youtu.be/4vpO7SolpvM

http://youtu.be/RpnNz2dJ0R0

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[Caleb Routt]

A great way to tell if the tornado is violent or not is to concider the environment in which the supercell is in. On the tornado scale you may want to look at the edges of the vortex. Usually if you see a very crisp funnel on each side that is an indication of strong updrafts. Of course horizontal vorticies is also a sign if you have large amounts of SRH that get pulled into the vortex.

No a tornado's size dosnt really indicate it's wind speeds. Friction can cause a vortex to shrink up and some articles I've read show that when you stop the flow at the base of the funnel you can have eruptions of updrafts that can be very violent. And of course suction vorticies inside the tornado could theoretically reach the speed of sound.

 

[MClarkson]

An EF0 can flip a car.

Not true. Cars are pretty aerodynamic from all sides, and they tend to have low centers of gravity. Not all cars are equal of course, but typically you should be thinking winds in the mid to upper 100s(mph) to massively move or flip a stationary car. A fast moving car would be more vulnerable, because its own momentum can work against it especially in a turn, but at lower end tornado speeds you'd have to blame the driver more than the wind.

Low end tornado winds can pretty easily knock a high sided commercial truck on its side, but that is completely different in terms of aerodynamics and center of gravity than a car.

 

[Nick Wilkes]

Not true. Cars are pretty aerodynamic from all sides, and they tend to have low centers of gravity. Not all cars are equal of course, but typically you should be thinking winds in the mid to upper 100s(mph) to massively move or flip a stationary car..

http://www.kptv.com/story/28804111/tornado-flips-vehicle-at-lane-community-college-in-eugene EF0 tornado in Oregon last year flipped a parked car.


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[Nick Wilkes]

My point being a weak tornado can flip a vehicle (better wording than car?) but it takes a violent tornado to loft them far distances and mangle/shred them.


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[MClarkson]

That car was either flipped by the poor choices of its driver OR the wind was much faster than EF0. Its not physically possible for a EF0 to have done that on its own, and its not close. But yes, some vehicles are much more vulnerable, and the more damage done to a vehicle, the more violent the tornado doing it was, for the most part.

 

[Wes Carter]

The driver didn't have a parking sticker or double parked? I'm trying to figure out how poor choices of the driver can affect a parked car.

I agree it was probably stronger than an EF0 at that point.


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[Royce Sheibal]

I've been actively chasing for going on 11? years now, and everything I've caught has always been F0-F2 range, other than 1. The only F3+ I've seen in person was the Beaver Crossing, NE Tornado in 2014. 1.5 Miles wide F3, totally rain wrapped. We knew there was a tornado, but it was virtually impossible to distinguish from the rain, the photos we took were a total fail.

We parked well to the SE of the rotation to be safe, and i noticed something I had never had in any of my other spots, a truly insane inflow. In every other F0-F2 I've seen, the inflow area dominated by vertical motion from the updraft, and much less horizontal. Sometimes the air is even calm despite proximity to the supercell. Meanwhile our F3 experience was quite the opposite. The inflow was 50-60mph well ahead of the storm in the inflow quadrant, in addition to a truly scary wall cloud around the entire cell unlike any I had ever seen. This was very similar to another large tornado back in 2002 that I happened to be in close proximity to whilst driving home from a competition (not chasing related). That day inflow winds were clocked at 80-90mph and nearly took us off the road despite being 2-3 miles from the tornado.

So for those of you looking to figure out of how to figure out when things are going to get nasty, check your inflow quadrant surface wind speeds, it might help.

 

[MClarkson]

I'm trying to figure out how poor choices of the driver can affect a parked car.

That it was in a parking lot does not mean it was parked.

 

[chrisbray]

This is what I always think of when I heard Violent Tornado.

 

[Dan Robinson]

Motion is a key identifier of a violent tornado. The more classic examples I know of had motion that is sometimes hard to believe you're not looking at something timelapsed.

Tuscaloosa definitely fits the bill. Watch this video at 2:30 and see how fast the dirt mass gets entrained in the vertical, probably the most rapid I've seen in any tornado:

9:59 or so in this video of the '98 Columbus:

And of course, Andover: