Most violent tornado in history?

[C M May]

In my opinion the Jarrel Tx tornado back in 1997 could be the most violent. The tornado of course was rated an F-5, but what made it so violent was the fact that it was moving so slow. Pretty much everything that was above ground was completely swept clean. (See pic below) Virtually everyone who was in shelter above ground didn't survive. Very sad. The tornado (like many other violent tornadoes) contained very violent updrafts that sucked away grass in fields. (Here is a pic below) Other notible tornadoes that have done that type of damage in fields include the EF-5 Philadelphia Ms tornado back on April 27, 2011. But we have to remember that large tornadoes are not the only ones that can be very violent. The small suction vortices can be just as strong if not stronger as the bigger tornadoes. Here is a video of a tornado from Australia.

It was very small in width but when it interacts with friction you increase surface inflow and at the corner flow you can have 200+ mph winds. Dr. Lewellen and Dr. Fiedler stated that in some cases in that region some tornadoes that have the structure of cyclostrophic balance aloft and a cyclostrophic imbalance at the ground can have winds close if not exceeding the speed of sound. View attachment 10872 View attachment 10873

Has some eerie similarities to Andover Kansas April 29, 2022 with those helical vortices.

 

[C M May]

Construction practices, survey practices, vegetation, population density, etc., all influence tornado damage ratings, and they've all (likely) varied quite a bit from time-to-time and place-to-place. The mobile radars and WSR-88D give us some chance to compare the larger-scale tornado circulations, but frequent radar upgrades leave us with a moving target. For what it's worth, here are the 10 strongest rotational velocities we've found with US tornadoes since 2009:

1. Tuscaloosa, AL, EF4 4/27/11 124 kt
2. El Reno, OK, EF3 5/31/11 124 kt
3. Calhoun Co., AL, EF4 4/27/11 123 kt
4. Tipton, OK, EF3 5/16/15 116 kt
5. Woodford Co., IL, EF3 11/17/13 116 kt
6. Cedar Co., NE, EF3 6/17/14 111 kt
7. El Reno, OK, EF5 5/24/11 110 kt
8. Yazoo City, MS, EF4 4/24/10 109 kt
9. Menifee Co., KY, EF3 3/2/12 108 kt
10. Jackson Co., AL, EF4 4/27/11 105 kt

For comparison's sake, Joplin was 99 kt, and the latest Moore tornado was 92 kt. The biggest question with radar data is sampling compared to ground level and the size of the tornado, which are obviously not equal in all cases. There are clear relationships between rotational velocity and EF-scale damage ratings, but it's still far from perfect given all of the different ways things can vary.

Can you elaborate a little on exactly what “rotational velocity” is referring to? I know it seems like it should be obvious but I figure I can’t be the only one with this question. Thanks.

 

[Jamie H]

Can you elaborate a little on exactly what “rotational velocity” is referring to? I know it seems like it should be obvious but I figure I can’t be the only one with this question. Thanks.

My understanding here is differentiating between the velocity recorded by radar (rotational velocity), against damage ratings on the ground. While a radar might record 200 mph winds rotationally, there may only be evidence of 160 mph winds when you assess the ground level damage.

I could be wrong of course!

 

[C M May]

My understanding here is differentiating between the velocity recorded by radar (rotational velocity), against damage ratings on the ground. While a radar might record 200 mph winds rotationally, there may only be evidence of 160 mph winds when you assess the ground level damage.

I could be wrong of course!

I don’t think I asked my question correctly. What I want to know is “what does rotational velocity” actually mean? It’s not the same as “wind speed” I assume. For example, Tuscaloosa 2011 is listed here with a RV of 124kt which is about 143mph. We know that the wind speeds in that tornado were well above that, so if RV doesn’t mean wind speed, what does it mean?

 

[C M May]

Re: Joplin, while the construction really doesn't support an EF5 rating, I think there are several other factors that do. In particular, the extraordinary debris granulation, extremely severe debarking/denuding of very large, healthy trees, very severe vehicle damage and extensive ground scouring. The debris granulation was probably as impressive as I've ever seen outside of possibly Jarrell and Parkersburg, as was the debarking/denuding of both large trees and low-lying shrubs. It may not be the most violent tornado on record, but I think it's a no-doubt EF5.

With respect to the parking stops, while I think the "anchored with rebar" bit is slightly misleading, it still seems to be a pretty impressive feat. I have several photos (ground level and aerial) of the parking stops, and it seems they may have been more twisted off than torn away from the rebar pins. I'm not sure what to make of the manhole covers being sucked away, but it's also pretty impressive.

Also I'm interested in where you heard this "sandblasting of rocks" and Jarrell being considered for an F6 rating. The original scale did extend all the way to 12 (in order to connect the Beaufort and Mach scales), but anything over F5 wasn't really intended to be used in practice. The infamous "____ tornado almost received an F6 rating" seems more of an urban legend than anything, as I've heard it connected with any number of tornadoes (Guin, Xenia, Bridge Creek, Jordan, Plainfield, etc).

I mostly agree with you about Joplin -- Again, I was not part of the survey.
But agreed it is a "No Doubt F5". And again, I am only addressing intensity - not violence.
I don't think Joplin is a candidate for "most intense".
I also think you are right about the parking stops.
As a kid, I used to do landscaping, and sometimes have to move parking stops around by hand to move equipment, etc.
I am a fairly strong guy, but you might be surprised how easy (ok not really easy) they are to move.
They are not really "anchored", I have seen a small car bump one and knock it off the off the rebar "pins".
They usually only weigh about 180 lbs, and can be rocked and twisted easy if they are not on flat ground.
A car being pushed forward (or backward for that matter) could easily scoot one of these things, and once
they get moving they are much easier to keep moving (static vs kinetic friction). Enough said.

Jarrell happened on Day 3 of an outbreak in KS, OK, and TX.

Shane -- You are right -- there was an unusual kind of gravity wave trigger in play at Jarrell.
I remember the day well. Part of our team moved south on Day 3, but did not go as far south as Jarrell.

The next day or so - at dinner, Matt Biddle and some others were discussing Jarrell and said that there
had been some speculation about F6, but I did not mean to imply that it was considered seriously.
There WAS apparently some amazing scouring of rocks.

The slow motion factor was a major part.

I saw a video by Al Pietrycha that showed an F0/F1 landspout that caused F3 damage.
It didn't move for 10-15 minutes, if I remember correctly.

-Truman

I’m confused by something you wrote regarding Joplin. You rank it high on intensity but not violence. I guess I look at intensity as meaning the same thing as violence. To me they both mean the same thing. Would you mind explaining your thinking on the difference between intensity and violence?

 

[C M May]

I always thought that the Pampa, Texas tornado packed some pretty strong winds, a real "drill bit" tornado

That Pampa tornado was amazing to watch. I think it was Tom Grazulis himself that said “if there was ever video evidence of 300mph winds at the surface, Pampa 1995 is it.”

 

[Jeff Wright]

A Lathe was made airborne.

Guin 74 was pretty stout.

My guess is that storms may have been more severe in prehistoric times...