Most violent tornado in history?

[Timothy Schaffer]

Great finds Shawn. Digging out gems is never spamming.

 

[Joshua Nall]

Yes Shawn, I enjoy you sharing your research with us. Thank you!

 

[TrumanBoyer]

Yes Shawn, I enjoy you sharing your research with us. Thank you!

I concur, and really appreciate you sharing. I have family in Middle TN, and I know firsthand of legends that go back many generations, "windroads", stone churches leveled, grave markers found miles away, no documentation -- no press, (no telegraph), just family stories...

Back to the "debate". My bet would be Jarrell TX, for wind intensity. I can't locate it at this time, still looking, but I have seen some video of its multivortex stage, before it darkened, and headed into town. I never saw a subvortex "cracking the whip" like in that storm. Coming around the back side of the circulation, then snapping forward and around to the north side, in the blink of an eye.

I was at Joplin, I personally put the damage at the high end of F4 - remember - it was the second survey that bumped it up to EF-5.
Tim Marshall cited the movement of concrete parking berms (or "car stops", or whatever they're called). I have other ideas about how they might have been moved, but I was not part of the survey. Anyway, I would rate Joplin as "low end" F5 at most.

There had even been some discussion about Jarrell being an F6, based on sandblasting of rocks outside of town. Ted Fujita's damage scale included F6 thru F12, I don't remember offhand exactly what F6 damage entails.

AGAIN I'M JUST TALKING ABOUT WIND INTENSITY HERE -- not really trying to address "violence".

Pavement Peeling is IMO the most astonishing thing to me. I realize that asphalt composition varies, as does road underlayment, strength of binder coats, etc., but watching (video of) ribbons of highway twisting through the air hundreds of feet high, and then scattering like a flock of scared birds. Takes my breath away...

Never seen this first hand, I have driven over stretches of (used to be) highway.

DOES ANYBODY have video, pics, stories of pavement-peeling storms ? Has an F4 ever done this ?

Thanks,

Truman

 

[Shawn Schuman]

I'm inclined to believe that ground scouring is a more reliable indicator of intensity than asphalt scouring, though neither of them is foolproof. Any number of F4 tornadoes have produced asphalt scouring (4/14/12 Kanopolis Lake, KS and 3/2/12 Henryville, IN being just two of a number of recent examples), and a number of tornadoes of EF3 or lower intensity have also produced scouring. Now that I think about it, the Pedernales Valley/Lake Travis F4 from 5/27/97 (mostly overshadowed by Jarrell) also caused ground scouring. Anyhow..

The 3/2/11 Henryville, IN EF4:



The 5/24/11 Canton Lake, OK EF3:



The 3/1/07 Americus, GA EF3:



And a 2004 tornado near Lind Center, WI which was rated F2:



Also I could have sworn there was a video shot near Watonga, OK back in the late 90s that showed a very narrow rope peeling up asphalt. It may even be on Youtube somewhere.

Of course, there are some caveats with this list. The Canton Lake tornado was almost certainly deserving of a higher rating, and NOXP recorded velocities of around 190 mph at something like 60m AGL, which is impressive. The Americus tornado also did some impressive damage to an industrial building if I recall, and a case could probably be made for an EF4 rating at some point. Still, I think it illustrates how many variables come into play with respect to asphalt scouring.

Ground scouring isn't a guaranteed indicator of violent intensity either, but it's pretty good supporting evidence, especially if the scouring is extreme and paired with severe debarking/denuding of trees and low-lying shrubs.

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.

Ryan McGinnis took one of the more impressive photos I've seen from Joplin.

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).

 

[Jeff Snyder]

I'm inclined to believe that ground scouring is a more reliable indicator of intensity than asphalt scouring, though neither of them is foolproof.
....
Ground scouring isn't a guaranteed indicator of violent intensity either, but it's pretty good supporting evidence, especially if the scouring is extreme and paired with severe debarking/denuding of trees and low-lying shrubs.
....
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.

My "issue" with ground scouring is that there is very little (if any) high-quality scientific experimentation examining ground scouring severity as a function of the many variables one experiences in a tornado (not the least of which is maximum wind speed). As far as I know, essentially the entirety of ground scouring information is anecdotal in origin (e.g., "this EF5 tornado had appreciable scouring, whereas this EF1 did not"). Of course, it makes some sense that the probability of scouring increases as wind speed increases, but I highly suspect that the duration of the wind, the amount of debris loading, soil type and condition (wetness, etc.), and specific vegetation type and health affect ground scouring. Consequently, I'm dubious of using scouring observations for inferring much about tornado intensity or behavior, particularly when there is massive debris loading (which there was in Joplin). I really hope that someone somewhere is looking into (or can look into) asphalt and ground scouring using calibrated wind research methods (e.g., wind tunnels, etc.) so we can better understand the relationship between scouring and wind speeds.

 

[Adam Lucio]

When talking about impressive damage done by tornadoes, probably the most Impressive one I've ever heard was the Greensburg tornado ripping at least on fire hydrant out of the ground. Im not sure if that was aided by a large piece of debris striking it, but still, thats impressive.

 

[Shawn Schuman]

I'd love to see some scientific rigor brought to the issue, but I'm not sure how practical that would be. It has the potential to be a valuable tool, though. As you said, there are many variables involved with both ground and asphalt scouring. It's all anecdotal, to be sure, but that's pretty much all we have. That seems to be the case with any number of issues when it comes to estimating tornado intensity.

As you said, debris loading pretty clearly makes a difference. This is most easily seen in rural areas where ground scouring begins (or intensifies) almost immediately downstream from a destroyed structure. The same can be said of debarking and denuding of trees. Of course, debris loading can play a big role in the damage caused to structures as well. Soil/vegetation factors also seem to play a role; for instance, at least subjectively, it seems that parts of Oklahoma and Texas may be more prone to ground scouring than other areas of the country. I'd be interested in digging into that a bit more at some point to see whether it's really borne out.

All of that said, I think we can still make some broad assumptions. At the very least there seems to be some sort of correlation between significant ground scouring and strong/violent tornadoes. It may not necessarily require a violent tornado to produce severe scouring, but I'd say it would add to the evidence. I don't think you can assign a rating based on ground scouring, but it's a useful piece of context. I feel the same about severe vegetation damage (particularly low-lying shrubs) and, to a lesser extent, vehicle damage.

I'm also interested in what role wind duration might play. The two extremes that come to mind are probably Jarrell, which lingered over some areas for 8+ minutes, and Philadelphia, MS which produced its scouring in literally seconds. Jarrell just scoured everything out and left nothing but a broad streak of mud. The Philadelphia tornado pulled up the grass in chunks, basically leaving large clumps of sod and an almost plowed appearance. The soil types are obviously very different, with what seems to be very clay-heavy soil in Neshoba/Kemper Counties.

Most have probably already seen it, but here's the scouring in question:

Watch video >

And Adam, I thought that was pretty impressive as well. Do you happen to remember where that occurred? I remember seeing the photos and the surrounding damage appeared to be pretty intense from what I recall. A vehicle or some other large debris strike seems most likely, but who knows. It reminds me a bit of the drive well pump (and, in a flourish of almost certain exaggeration, a full 40 feet of pipe) which was said to have been pulled from the ground by the 1893 Pomeroy, IA tornado.

 

[Shane Adams]

This topic is one of those that will always be open to interpretation. The Tri-State Tornado caused major damage while having an incredible forward speed while a tornado such as Jarrell caused complete destruction while moving very slowly. I've always wondered how much that has to be taken into account.

It almost seems more impressive (if also obvious) when a tornado causes complete destruction while barely moving, because a lot of what causes the destructive impact of violent tornadoes in many cases is the forward speed of impact onto structures. Imagine a tornado with >200mph top end winds, moving at 60mph, impacting a neighborhood. Though the tornado would move through the structures quickly and only impact them directly for mere seconds, that forward speed of impact would certainly aid in creating the damage, perhaps even compensating for the lack of time actual tornadic winds spent over structures. You could reverse this and talk about how a slow-moving tornado, while lacking the forward speed of impact, could just grind away at structures, aided by the airborne debris which keeps bashing at everything still standing.

IMO the reason Jarrell is so unique is the mesoscale processes which lead to it. My ultimate chase goal is to witness a storm/tornado evolution such as Jarrell was. But I think that was a once-in-a-lifetime event.

 

[TrumanBoyer]

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

 

[Shawn Schuman]

IMO the reason Jarrell is so unique is the mesoscale processes which lead to it. My ultimate chase goal is to witness a storm/tornado evolution such as Jarrell was. But I think that was a once-in-a-lifetime event.

It's certainly unusual, but it's not entirely unprecedented, at least in terms of the basic evolution of the event. I was doing some research when I wrote my blog and came across a handful of events that featured similar basic pieces (extreme instability in the presence of modest shear, gravity waves and a tornadic supercell sorta back-building along a boundary like a zipper). Except, you know, those events didn't happen to feature one of the most intense tornadoes ever recorded.

I don't think I have any of that info on hand, but I can try to find it if you'd like.

Concerning the parking stops, the NWS survey said they weighed "approximately" 300 pounds. I don't know where they got that figure from, but it's possible. It seems most of them weigh between 200 and 275 lbs from what I've seen. Another thing I noticed is that the rebar "anchoring" appears to literally be pieces of rebar. Most of the time, at least with modern parking stops, they use a pin with a head on it that looks sorta like a really big nail. I don't know how much difference the head would make in practice, but it seems like it'd provide a little more anchoring and resistance than just a straight piece of rebar.

Anyhow, this is what I was talking about. Note how the stops seem to have been twisted more so than torn away.







Location of photos in 1-2-3 order:

 

[TrumanBoyer]

...a tornadic supercell sorta back-building along a boundary like a zipper).

I don't think I have any of that info on hand, but I can try to find it if you'd like.

Concerning the parking stops, the NWS survey said they weighed "approximately" 300 pounds. I don't know where they got that figure from, but it's possible. It seems most of them weigh between 200 and 275 lbs from what I've seen....

...Anyhow, this is what I was talking about. Note how the stops seem to have been twisted more so than torn away.

I love the description "like a zipper". In 2000, I worked a small outbreak in the extreme North TX Panhandle. It was a classic upwelling type of setup with an almost parallel Warm Front and Cold front clash. The scrimmage line was a nearly perfect East to West line. I caught a couple of spin ups at Texhoma, but the big cell of the day raced eastward so fast I could not catch it.

"Like a zipper" is EXACTLY what I thought... (Great Minds think alike !!)

You have already done so much, but if you have info on setups similar to Jarrell - AND you don't have to do too much digging.....
I am super curious about these setups where you get basically one big giant violent storm, and pretty much nothing else.

I think the Barneveld Wisconsin F5 was like this, but it was after midnight, and I bet there is not a lot of documentation.

Maybe sometime in the future we'll be able to feed some of this info into a computer model and see what happens...

As for Parking Stops - WOW. I never saw those pics. I have seen them as listed as low as 150 lbs, and as high as 300. The ones in your photo look large and heavy, and the one in the foreground definitely looks twisted. I also don't see any "skid marks" from tires OR THE STOPS. And in the mud there are no apparent marks in the turf leading up to the car stops. WOW. HOW COULD THAT HAPPEN ??

 

[Shane Adams]

As for Parking Stops - WOW. I never saw those pics. I have seen them as listed as low as 150 lbs, and as high as 300. The ones in your photo look large and heavy, and the one in the foreground definitely looks twisted. I also don't see any "skid marks" from tires OR THE STOPS. And in the mud there are no apparent marks in the turf leading up to the car stops. WOW. HOW COULD THAT HAPPEN ??

Perhaps being hit squarely by a suction vorticy at just the right angle? A lot of upward thrust inside violent tornadoes, and maybe that force compressed down into a small, only-seconds-long sub-vortex could've provided the momentary upward blast to dislodge and throw them?

 

[Dan Robinson]

The movement of anchored concrete parking stops is by far the most impressive tornado damage I think I've ever seen. I always envisioned surface friction would temper tornadic wind speeds that close to the ground. Normally a parking stop wouldn't need bracing against vertical movement, hence the lack of the 'nail head' on the rebar. It's interesting that all of the stops look like they twisted off as they moved, as each stop's rebar is bent in opposite directions. I think Shane's theory is probable - could this have been a subvortex that traveled right along the line of stops, plucking each one as it went?

And is it certain that those are concrete stops? They make them out of plastic and rubber in the same colors.

 

[Shawn Schuman]

...a tornadic supercell sorta back-building along a boundary like a zipper).

I don't think I have any of that info on hand, but I can try to find it if you'd like.

Concerning the parking stops, the NWS survey said they weighed "approximately" 300 pounds. I don't know where they got that figure from, but it's possible. It seems most of them weigh between 200 and 275 lbs from what I've seen....

...Anyhow, this is what I was talking about. Note how the stops seem to have been twisted more so than torn away.

I love the description "like a zipper". In 2000, I worked a small outbreak in the extreme North TX Panhandle. It was a classic upwelling type of setup with an almost parallel Warm Front and Cold front clash. The scrimmage line was a nearly perfect East to West line. I caught a couple of spin ups at Texhoma, but the big cell of the day raced eastward so fast I could not catch it.

"Like a zipper" is EXACTLY what I thought... (Great Minds think alike !!)

You have already done so much, but if you have info on setups similar to Jarrell - AND you don't have to do too much digging.....
I am super curious about these setups where you get basically one big giant violent storm, and pretty much nothing else.

I think the Barneveld Wisconsin F5 was like this, but it was after midnight, and I bet there is not a lot of documentation.

Maybe sometime in the future we'll be able to feed some of this info into a computer model and see what happens...

As for Parking Stops - WOW. I never saw those pics. I have seen them as listed as low as 150 lbs, and as high as 300. The ones in your photo look large and heavy, and the one in the foreground definitely looks twisted. I also don't see any "skid marks" from tires OR THE STOPS. And in the mud there are no apparent marks in the turf leading up to the car stops. WOW. HOW COULD THAT HAPPEN ??

The photos are on my blog. The parking stops were almost certainly impacted by intense subvortices, likely several of them as they translated very quickly around the core, and they were lifted and thrown by wind alone. There are too many of them for it to be caused by debris strikes or something of that nature, and that wouldn't really aid in tearing them from the anchoring and lofting them anyway. The thing I find interesting is that they were thrown in completely different directions. The first two photos are almost due west, and the third is north-northeast. The second location is around 150 yards east-southeast of the first, as you can see in the aerial photo. There were probably another two dozen parking stops thrown from the parking lots immediately north and northwest of the hospital as well, and most of those were thrown in directions ranging from east to north. Most of them seem to have been thrown 30-40 yards, but some of them traveled 100+ yards.

Re: Jarrell-like setups, I'll see if I can dig up some of the examples I mentioned when I have time. Barneveld was actually part of a pretty significant tornado outbreak, with nearly 50 tornadoes in total and I believe four or five strong tornadoes besides the F5. The setup was also more of a typical scenario, and there was a very intense jet streak punching into Iowa/Wisconsin so I'd assume the shear was pretty impressive.

 

[Shawn Schuman]

The movement of anchored concrete parking stops is by far the most impressive tornado damage I think I've ever seen. I always envisioned surface friction would temper tornadic wind speeds that close to the ground. Normally a parking stop wouldn't need bracing against vertical movement, hence the lack of the 'nail head' on the rebar. It's interesting that all of the stops look like they twisted off as they moved, as each stop's rebar is bent in opposite directions. I think Shane's theory is probable - could this have been a subvortex that traveled right along the line of stops, plucking each one as it went?

And is it certain that those are concrete stops? They make them out of plastic and rubber in the same colors.

Yeah, they're concrete. The NWS survey said they were "approximately 300 lbs."