Most violent tornado in history?

[MClarkson]

That is impressive. They look pretty aerodynamic too... It would be interesting to put a typical parking stop in a wind tunnel and see when they cut loose. The terminal velocity equation (I estimated 125kg, a 0.4m surface area, slightly more aerodynamic than a human, and a typical 950mb atmosphere) gives about 170mph. They probably cut loose above that speed, especially with a bit of anchoring. So I'd guess greater than 175mph at that level(about 10cm). Maybe even above 200mph. Pretty impressive so far into the friction layer. Someone with a better knowledge of tornado boundary layers than me would have to tell you what that relates to at house or human height.

 

[Shawn Schuman]

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.

Okay, I can't seem to find the research I had saved, but I know of at least one example off-hand. First, obviously, the other tornadoes on 5/27/97 formed under similar conditions: extreme instability, relatively weak shear and initiation along a surface boundary aided by a gravity wave. Each of the tornadoes formed along the same boundary and shared the same rough southwesterly motion as they propagated "backward" along it.

Anyhow, the event that immediately comes to mind is the Lake Whitney, TX F3 on 5/12/00. The setup was decidedly Jarrell-esque. There was a stalling cold front and prefrontal trough drifting southeastward into an extremely unstable airmass (4,500+ j/kg), with the cold front also acting as sort of a pseudo-dryline with much drier air behind it. Winds were fairly weak throughout the column, but a mesoscale low had formed to the southwest and caused winds in the Waco/Lake Whitney area to back. As with Jarrell, the storm propagated to the southwest along the boundary with the tornado near the leading edge. I don't believe this event featured a gravity wave, however.

The boundary is clearly visible on both visible satellite and radar.





Shot of the tornado for good measure:

There have been other cases, mostly in Central Texas, but I can't remember them right now. It's a pretty unusual sequence of events, but certainly not unprecedented in that particular area.

Edit: Actually I just found the website those photos came from. Lon Curtis has a fantastic summary here.

http://homepages.vvm.com/~curtis/May_12.html

 

[Dan Robinson]

The Jarrell storm evolution/tornadogenesis seems oddly similar to the May 19, 2012 event in Kansas, where convection 'unzipped' along a boundary. The 5/19/12 tornadoes appeared to begin in landspout fashion, with high cloud bases and no apparent wall clouds or RFD clear slots (at least from the images and videos I know of). The 5/19/12 Rago tornado was particularly intense and fully condensed, but could arguably still be considered a landspout, or at least some sort of landspout hybrid. I haven't seen a clear storm structure shot of Jarrell - is it possible that the genesis of Jarrell was more landspout-ish similar to 5/19/12?

 

[Marcus Diaz]

One storm that comes to mind in terms of a SWrly storm motion was a tornado near White Deer, TX back in the early 00s. I want to say Tim Marshall chased that storm and got some pics and vids of that tornado. I was much younger back then so I don't remember the exact date.

 

[Shawn Schuman]

The Jarrell storm evolution/tornadogenesis seems oddly similar to the May 19, 2012 event in Kansas, where convection 'unzipped' along a boundary. The 5/19/12 tornadoes appeared to begin in landspout fashion, with high cloud bases and no apparent wall clouds or RFD clear slots (at least from the images and videos I know of). The 5/19/12 Rago tornado was particularly intense and fully condensed, but could arguably still be considered a landspout, or at least some sort of landspout hybrid. I haven't seen a clear storm structure shot of Jarrell - is it possible that the genesis of Jarrell was more landspout-ish similar to 5/19/12?

You're correct. Here's a good paper on that very topic:

http://journals.ametsoc.org/doi/abs/10.1175/MWR3301.1

And I'd forgotten about the Rago event. I'm a little fuzzy on the details, but I do remember it being something of a mesoscale accident, with the same sort of "zippering" back-building along a boundary. I'll have to go dig more into that.

 

[Mike Johnston]

Yeah, I guess you can find similar events, but don't you almost have to cite the gravity wave when talking about Jarrell? It seemed like a key, probably even necessary, to the genesis of that storm. As I recall, the gravity wave originated in Arkansas the previous day? Seems like it was about the closest thing to a "mesoscale accident" you could find.

 

[Shawn Schuman]

Yes, the gravity wave originated from a dying MCS that had formed in Oklahoma the previous day and passed into Arkansas overnight. It's hard to say whether the gravity wave was a necessary component. It looks as if the initial updrafts formed prior to the gravity wave in the presence of extremely strong moisture convergence (further aided by a nearby mesoscale low) on the boundary. The Jarrell storm did develop explosively coincident with the passage of the wave, though, which certainly suggests it played some sort of role. I believe it was a paper by Corfidi that made the case that the gravity wave may have played a role in the "zippering," allowing new updrafts to continually form along the southwest flank as it propagated along the boundary.

Whether any of this would have happened without the gravity wave is anyone's guess. My sense is that things would have played out differently without it. The cap was very strong that day (and had been for several days previous, which is what allowed such tremendous instability to build up), so clearly something was needed to break it. I'd imagine it may be the case that gravity waves contribute to a number of events like this.

 

[Shane Adams]

Anyhow, the event that immediately comes to mind is the Lake Whitney, TX F3 on 5/12/00. The setup was decidedly Jarrell-esque. There was a stalling cold front and prefrontal trough drifting southeastward into an extremely unstable airmass (4,500+ j/kg), with the cold front also acting as sort of a pseudo-dryline with much drier air behind it. Winds were fairly weak throughout the column, but a mesoscale low had formed to the southwest and caused winds in the Waco/Lake Whitney area to back. As with Jarrell, the storm propagated to the southwest along the boundary with the tornado near the leading edge. I don't believe this event featured a gravity wave, however.

I've always wondered about these two events. Something about central TX because these are likely the best two examples of such an extreme (and somewhat rare) event. You mentioned a gravity wave that possibly enhanced the Jarrell event, but beyond that, the setups were fairly similar. My question is, could this perhaps be some type of phenomenon that's indigenous to that particular geographical area (central TX) such as the Denver Convergence Zone or the caprock....but just with far less frequency?

 

[Simon Brewer]

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.

I agree, more research is needed with respect to tornado ground scouring. The large, slow moving (crawling) & debris loaded 1997 Jarrell, TX tornado scoured a relatively thin layer of asphalt over a matter of minutes. The skinny (at the time), fast moving (50-60mph), and significantly less debris loaded 2012 Henryville, IN tornado had an individual suction vorticy north of Palmyra, which peeled large sections of very thick asphalt (one section weighing 10,000 to 20,000 lbs) over an estimated time period of less than half a second, throwing them 30-50 meters causing deep impact craters downwind! Possibly even more impressive was the deep trench scoured from the fast moving and relatively skinny 2011 Philadelphia, MS tornado. Highest wind speeds occur with these individual suction vorticies, which can cause incredible damage in a fraction of a second.
Friction at ground level is an incredible force for winds to overcome, which makes damage very close to the ground very significant. Because suction vorticies can be so small in diameter and short-lived I'm not surprised some tornadoes can cause significant ground scouring in one area, but not have widespread significant damage over the entire path length.

 

[Zack Hargrove]

I view the Plainfield, IL F5 in 1990 as a similar type setup as Jarrell... Not too sure about gravity wave interaction, but it was all about a well placed boundary, modest shear and insane CAPE (>8000 J/kg)

 

[Skip Talbot]

I view the Plainfield, IL F5 in 1990 as a similar type setup as Jarrell... Not too sure about gravity wave interaction, but it was all about a well placed boundary, modest shear and insane CAPE (>8000 J/kg)

Another good example is the Roanoke F4 in central Illinois on July 13, 2004. At face value it seems similar to Jarrell, but I haven't read too much on that event. Roanoke has been compared to Plainfield, however. The event featured dews over 80, was weakly sheared, extremely unstable and resulted in a slow SE moving violent tornado. Intersecting outflow boundaries played a key part in storm initiation and tornadogenesis:

http://www.crh.noaa.gov/images/ilx/pdf/Bak_Shimon_Huettl.pdf

 

[Pete Kustra]

I noticed that there's no mention by anyone of the 4/27/2011 Philadelphia, MS tornado here - it scoured soil down to 2 feet, much deeper even than the scouring from the 1999 Bridge Creek tornado. It probably had some of the highest ground-level winds of any tornado in recorded history.

 

[Royce Sheibal]

Call me a Homer, but how about the Easter Sunday Tornado of 1913 in Omaha, NE? Surprisingly well documented for being so long ago, and the damage / toll was just incredible. The tornado was so terrible that Omaha set out to build the world's first Tornado-Proof office building, which is still standing right next to my office today!

 

[calvinkaskey]

I would think Joplin would have to at least be in the Discussion with the high death toll in more of a "modern time".

Maybe in terms of energy because it seemed like ef-3 damage made up half or more of the total area covered.

 

[calvinkaskey]

Because it's impossible to record at-ground tornadic windspeeds, determining which one was "most violent" is also impossible. But, here's a list of some of the most-noteworthy F5 tornadoes in recorded history...might be a good place to start the debate:

Tri-State tornado(es) of MO/IL/IN - March 18, 1925

Xenia, OH - April 3, 1974

Andover, KS - April 26, 1991

Jarrell, TX - May 27, 1997

Bridge Creek/Moore/OKC, OK - May 3, 1999

Greensburg, KS - May 4, 2007

This is a conversation that could go on forever. It will be interesting to see who bites.....

Yeah the tri state tornado/es reached over 73mph in foward motion adding to it's wind speeds. No way you could chase it safely.