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Enhanced Fujita Ratings Debate Thread

So I came across this thread over on the Stormtrack forums talking about the Fujita Scale(s), and thought I'd share a link to it here as I would recommend checking it out:


The OP even has a possible suggestion on dealing with discrepancies between radar-based wind measurements and damage-based wind estimations:

Whatever the reasons, I personally think they need two scales (or just do away with the Enhanced Scale and return to the original Fujita scale).

Tornado Intensity Rating (TIR)
One for actual measured wind speeds at any point during its tenure between touchdown to lifting. I believe the original Fujita Scale ratings would be acceptable here.

Tornado Damage Rating (TDR)
Ratings here would be based on the damage done. Do away with the Enhanced Fujita nonsense. Call it the TDR Scale. Levels 1-5.

I just thought it was worth sharing, and I think I'll let you guys peruse and discuss that 'til the cows come home (then rope the cows into the discussion:p).
 
1: it's an analogy about distributions, not literal.
2: that doesn't mean the relationship can't hold in general.
3: the relationship's clearest at the strongest categories and I wouldn't say there's too much overlap. Survey issues could just as easily be making the relationship less, not more clear.
4: I don't have the data to judge exact locational correlations (which could get very problematic due to DI sparseness), you could ask Emmerson. The sample was about four hundred which I'd prefer to a couple of anecdotes.
5: There's no such thing as the 'physical wedge' that's distinct from the 'visible wedge'. 'Wedge' is a description of the condensation funnel and/or debris cloud's shape. The shape depends on factors like humidity, cloud/LCL height etc. as well as pressure drop and gradient. I don't have time to do a literature review, though I've seen at least one case where the doppler max was outside the visible funnel and one paper claim the top of the funnel is a better indicator, but it's not been systematically explored. John T. Snow's 1982 caution "care must be taken in inferring the size or structure of the core from the shape of the condensation funnel" applies.

My example was intended to show that there's no need to invoke a 'hidden violent core', a 'secondary stove pipe shaped column hidden inside the main condensation funnel' or a 'separate smaller tornado inside'. Of course they're not going to neatly coincide (see above). I just think these analogies are based on a poor heuristic that appears to nearly equate surveyed and visual widths, which often isn't the case.

6: you said "in reality, tornadoes (particularly wedges) fail to develop a violent core". 'Particularly' can be reasonably construed as implying wedges are more prone to not developing a violent core than non-wedges.


I don't think I've missed your points (there's about three issues at play here) I just don't agree with many aspects of them.
With all due respect, you have, but again, it’s my fault for, quite honestly, piss poor clarification.

Obviously “wedge” is nothing but a visible representation of what a tornado looks like.

Im using the word “wedge” just as a descriptive term for the outer parent funnel since it’s easier to visualize. Which is why I distinguished between “visible” and “physical” (Again, a substantial clarification fault on my part)

Going back to the violent core, this quote from my response to Grand Poo Bah is what I was actually trying to say here.

“Exactly what I’m talking about, a rare group of wedge tornadoes develop a central core, and it’s these tornadoes that cause the most extreme feats of damage known.

Obviously though when this being say said, I don’t mean that tornadoes that lack a violent core don’t produce extreme damage.

All wedge tornadoes have a meso vortex structure, but only few manage to develop a central core structure.

Greensburg and Joplin are examples of meso vortex structures that never developed a violent core, but the meso vortices are what did the extreme damage.

Smithville, Bass-field, Jarrel, Bridge creek, Moore 2013, and Piedmont are examples of wedges that did manage to develop a violent core.

The main point being that despite how impressive a TVS looks, it doesn’t always correlate to where the most extreme damage is going to be because in the vast majority of cases, meso vortex structures simply can’t produce a consistent swath of extreme damage due to the instantaneous nature of violent winds.”


And another quote talking about the same thing.

To clear up any confusion, meso vortices can in fact inflict extreme damage as well, but the area of damage is consequently more random and patchy rather than consistent. Violent tornadoes can produce that sort of damage just from meso vorts alone. Which I can assume is where the confusion came from when you responded to my point about “most wedges fail to develop a violent core” which is true. Core structures inside wedges are rare, again, most wedges are dominantly meso vortex structures, and these meso vortices can produce violent damage, but aren’t considered a core.

I’m not “invoking” anything, these structures inside tornadoes do exist, Ted Fujita, and many studies including the one I posted a few comments back (Figure 6) confirms this. Which just by looking at the damage path of wedge tornadoes, it’s easy to make out if they are meso vortex dominant (which almost all of them are, and again, can do extreme damage themselves) or the rare few that do develop a violent core. (Which again, “core” is a structural term, and is not in any way saying that non wedges or even wedges that never develop one don’t do violent damage)
 
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With all due respect, you have, but again, it’s my fault for, quite honestly, piss poor clarification.

Going back to the violent core, this quote from my response to Grand Poo Bah is what I was actually trying to say here.

“Exactly what I’m talking about, a rare group of wedge tornadoes develop a central core, and it’s these tornadoes that cause the most extreme feats of damage known.

Obviously though when this being say said, I don’t mean that tornadoes that lack a violent core don’t produce extreme damage.

All wedge tornadoes have a meso vortex structure, but only few manage to develop a central core structure.

Greensburg and Joplin are examples of meso vortex structures that never developed a violent core, but the meso vortices are what did the extreme damage.

Smithville, Bass-field, Jarrel, Bridge creek, Moore 2013, and Piedmont are examples of wedges that did manage to develop a violent core.

The main point being that despite how impressive a TVS looks, it doesn’t always correlate to where the most extreme damage is going to be because in the vast majority of cases, meso vortex structures simply can’t produce a consistent swath of extreme damage due to the instantaneous nature of violent winds.”
And another quote talking about the same thing.

To clear up any confusion, meso vortices can in fact inflict extreme damage as well, but the area of damage is consequently more random and patchy rather than consistent. Violent tornadoes can produce that sort of damage just from meso vorts alone. Which I can assume is where the confusion came from when you responded to my point about “most wedges fail to develop a violent core” which is true. Core structures inside wedges are rare, again, most wedges are dominantly meso vortex structures, and these meso vortices can produce violent damage, but aren’t considered a core.

Obviously “wedge” is nothing but a visible representation of what a tornado looks like.

Im using the word “wedge” just as a descriptive term for the outer parent funnel since it’s easier to visualize. (Again, a substantial clarification fault on my part)

I’m not “invoking” anything, these structures inside tornadoes do exist, Ted Fujita, and many studies including the one I posted a few comments back (Figure 6) confirms this. Which just by looking at the damage path of wedge tornadoes, it’s easy to make out if they are meso vortex dominant (which almost all of them are, and again, can do extreme damage themselves) or the rare few that do develop a violent core. (Which again, “core” is a structural term, and is not in any way saying that non wedges or even wedges that never develop one don’t do violent damage)
I've never understood why people consistently call Greensburg the "lowest-end EF5" since the implementation of the EF scale. Is it just due to only seven houses receiving EF5 damage, according to Timothy Marshall's survey of the town (which is actually quite fascinating)? Possibly. I mean, it produced some very extreme tree damage:
1749049724437.png
I just feel like Greensburg, and the family it was part of, are very underestimated in terms of power.
 
I've never understood why people consistently call Greensburg the "lowest-end EF5" since the implementation of the EF scale. Is it just due to only seven houses receiving EF5 damage, according to Timothy Marshall's survey of the town (which is actually quite fascinating)? Possibly. I mean, it produced some very extreme tree damage:
View attachment 43634
I just feel like Greensburg, and the family it was part of, are very underestimated in terms of power.
This comment here does a good job showing the damage implying a meso vortex structure through town.
Yeah that is scouring, the core was pretty narrow - but not crazily small - main swath of that inner vortex ranged from 75-130 yards wide or so, but EF3+ damage extended very near a mile in width at its peak. I won’t lie I myself am very perplexed at the structure and damage pattern of the tornado. Satellite imagery like that image shows a well pronounced vortex and centerline (along with some very impressive wind-rowing as it enters town) but then when it gets to Greensburg it kind of just disappears I guess lol. The main violent damage swath is skewed quite a lot more toward the left of the center of the vortex than on the right side, but structural damage was rather inconsistent for its entire path. On Highway 183 there was scouring and damage approaching or exceeding EF4 intensity evident along a nearly 1.3 mile stretch from north to south along the highway, albeit the scouring was sporadic at times and there wasn’t really a clear defined centerline.

Here’s some photos that really show just how completely random the bursts of extreme winds were.
View attachment 22218
View attachment 22219
View attachment 22225
Three homes that sustained EF1-EF2 damage surrounded by incredible vegetation damage, including completely stripped and debarked shrubbery in the second photo, and grass ripped from the ground in the last image.

View attachment 22220
This area of damage genuinely confuses me. An extremely intense subvortex misses the house to the left by literal feet and the property is surrounded by extreme vegetation damage yet no where near violent structural damage to this relatively poorly built home. Reminds me of the image from Guin showing an intact home right next to EF5-level vegetation damage.
View attachment 22222
Same home from the south looking north, homes a block south and north were completely flattened or wiped away experiencing winds that were no doubt well into the EF5 range, not to mention the ridiculously high-end debarking including low-lying shrubs on both sides of the property. A couple home owners never located their vehicles in this area, mainly because they were essentially pulverized to pieces which you can make out within the debris field, yet that lone home remains standing.

And this photo taken outside of Greensburg is a good example that meso vortices can produce extreme damage.
1749050389927.jpeg
 
Regarding physical evidence of tornado structures.

Here a three examples of tornadoes that contained a violent core. Hackleburg, Bridge Creek, Smithville.

Notice the total lack of any random damage patterns (the damage isn’t patchy) and cycloidal markings, instead, you have a simple, consistent path of extreme damage. Also notice that your extreme damage area is narrow, then you have an broad area of light damage.
1749051287835.jpeg1749051398047.png1749051444507.png

This photo from Smithville shows this well.
1749051831358.jpeg
The core hit this unfortunate residence square on, ground scouring, clean slab, completely debarked trees, and then just 150yards away sits a house that’s completely intact. Only a small part of the roof was lifted off.

One would think the tornado was a drill bit, but this tornado was over a thousand yards wide when it passed through here. However, instead of containing a multi vortex structure, it had a core structure. So even though the house was well inside the wind field of the tornado, it survived; I doubt it would’ve escaped this lightly had the tornado contained a multi vortex structure within its parent funnel.
 
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I've never understood why people consistently call Greensburg the "lowest-end EF5" since the implementation of the EF scale. Is it just due to only seven houses receiving EF5 damage, according to Timothy Marshall's survey of the town (which is actually quite fascinating)?
It's because until relatively recently there weren't a lot of damage photos associated with the tornado's most extreme feats. I think @Western_KS_Wx's research (mainly digging up a TON of new damage photos) was the turning point in shattering that misconception.
 
The only EF5 I could actually consider marginal would be Rainsville. Mainly due to the fact the buildings it swept away weren’t that well built. But if you look at some of the contextual damage from Rainsville, it yet again speaks for itself.
 
It definitely is, A Guy is a clever fellow, but the post completely misses my point though, all fault does lie with me for not clarifying what I meant regarding the violent core bit, which is what led to the misunderstanding in the first place.
I completely understand what both of you are saying. You two are very intelligent and are discussing things in a logical (non-emotional) manner which is rare these days. So it is a great discussion.

Now, I do strongly disagree with this comment: “A lot of tornadoes that exhibit ef5 level damage look relatively “unimpressive” on radar velocities even while in close proximity, and even ones that do fail to match or surpass other TVS on weaker tornadoes".

Given personal experience (subjective of course) and current research, I see no merit in this point on the whole. There are always exceptions, of course. I don’t think we’re changing each others mind though.
 
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Now, I do strongly disagree with this comment: “A lot of tornadoes that exhibit ef5 level damage look relatively “unimpressive” on radar velocities even while in close proximity, and even ones that do fail to match or surpass other TVS on weaker tornadoes".

Given personal experience (subjective of course) and current research, I see no merit in this point on the whole. There are always exceptions, of course. I don’t think we’re changing each others mind though.
I can think of a few examples of this, but can also think of a lot where the radar presentation matched the violence. Jarrell, Matador, as well as some of the 4/27/11 tornadoes didn't look over-the-top on radar, yet produced some incredibly violent damage. Smithville is an example of this, reflectivity and velocities on that storm didn't scream "ultra-violent EF5" to me, yet it was potentially the most violent tornado we've ever accurately documented. Of course, you could attribute that to the fact that it reached EF5 intensity in literal seconds, so I guess it's not a perfect example. Others from 4/27/2011 include Philadelphia, Cullman, and Rainsville (the lattermost was in a radar hole so it isn't a great example either).

Mayfield, Greenfield, Greensburg, Joplin, Tuscaloosa, and Moore 2013 absolutely matched the violence of their radar presentations though. It's a bit of a double-edged sword in that sense, I guess. There's definitely a few more that I'm not naming ATM but it's strange how you can give a lot of examples of very violent tornadoes with a mixed bag of radar presentation. It may have to do with the orientation of the radar beam in conjunction with the storm/mesocyclone geometry or something.
 
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There have really been only two legitimately violent tornadoes in recent memory in my mind that had a radar velocity signature that generally betrayed their intensity, and they were the Cookeville tornado in 2020 and the Matador tornado in 2023.

GWX had various issues back on 4/27 (and in that era in general). If you increase the radar tilt slightly in the Smithville or Phil Campbell cases, it becomes much more obvious. Actually in the Phil Campbell case, it was evident on the lowest tilt.

1749073322854.png
 
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I completely understand what both of you are saying. You two are very intelligent and are discussing things in a logical (non-emotional) manner which is rare these days. So it is a great discussion.

Now, I do strongly disagree with this comment: “A lot of tornadoes that exhibit ef5 level damage look relatively “unimpressive” on radar velocities even while in close proximity, and even ones that do fail to match or surpass other TVS on weaker tornadoes".

Given personal experience (subjective of course) and current research, I see no merit in this point on the whole. There are always exceptions, of course. I don’t think we’re changing each others mind though.
Matador and Jarrel definitely didn’t look like they were capable of the damage they did based on radar, even Smithville didn’t look like it was capable of the damage it did on radar, and those are just a few examples.

Obviously though we can respectfully agree to disagree.
 
There have really been only two legitimately violent tornadoes in recent memory in my mind that had a radar velocity signature that generally betrayed their intensity, and they were the Cookeville tornado in 2020 and the Matador tornado in 2023.

GWX had various issues back on 4/27 (and in that era in general). If you increase the radar tilt slightly in the Smithville or Phil Campbell cases, it becomes much more obvious. Actually in the Phil Campbell case, it was evident on the lowest tilt.

View attachment 43652
Correct me if i’m wrong, but the Grinnell, KS tornado didn’t look super impressive on radar as well.
 
IMG_9851.jpeg
On the other hand, the recent Plevna, KS tornado had one of the most impressive velocity couplets I have ever seen. But so far with the damage photos/videos avaliable, I’ve seen nothing that suggests a tornado higher than a typical EF4.
 
Unrelated to the current discussion, but I recently came across this photo from the 2024 Minden tornado and it made me go "hmmm..."

I initially agreed with the EF3 rating, but I have to say this particular home is definitely a head scratcher. It appears to be a large and well-constructed home swept completely away, and this photo was taken the day after the tornado, so no cleanup here. Unless there were major construction flaws not visible here, the adequate anchoring + the partial debarking in the background seems like enough support for at least low-end EF4. Plus, the 224 MPH DOW measurement is (IMO) further credence that the original F scale's wind speed estimates were more accurate than the EF scale.
73481571007-minden-tornado-004.jpg


And to alleviate any confusion, the home above is a completely different structure from this one. For the second one, I actually agree with EF3 as it was much smaller than the home above and was obliterated in a sub-violent fashion despite the anchoring.
Minden%2C_IA_EF3_tornado_damage.jpg
 
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