Enhanced Fujita Ratings Debate Thread

[Lake Martin EF4]

It absolutely did. Some of the photos I've seen were amazing and pointed to extreme intensity. I'll post them later.

Here you go @slenker:

I take back what I said about the sterling tx tornado being mid range ef4, upon closer inspection through numerous photos of the survey, I have no doubt in my mind this was en ef5; I don’t say these things willy nilly either.

Mesquite trees in some of these were actually completely debarked, some photos look like a galactic laser atomized the area. This scouring combined with tree damage puts this thing on par with matador, 2013 Moore, and Chickasaw to name a few.

Keep in mind there’s no debris loading that could’ve enhanced the scoring or debarking, I don’t even want to imagine this hitting a town.

Yes, those are, indeed, fully debarked mesquite trees. Mesquite trees, for the record, are some of the most durable trees ever, and I believe I saw them mentioned as the poster child for "indestructible trees". It's apparently very hard to remove the bark even partially, and yet...

EDIT: I'm not even sure 30 seconds have passed and 2 people have already liked this post. Lol

 

[jiharris0220]

While I agree with the overall message he’s attempting to convey, El Reno 2013 and Hollister 2024 aren’t great examples for conveying how misapplied the scale is. El Reno 2013 IMO is very overrated in its intensity to the general public outside of some impressive vehicle damage, and I haven’t seen a single image from Hollister 2024 that even remotely points to a significant EF2+ tornado. Extremely violent tornadoes are fully capable of incredible damage to the ground and trees, and neither of those two did such a thing (El Reno 2013 did have like, one tree that was debarked impressively though). Hollister 2024 literally did nothing substantial on the ground at all, it wasn’t even close to being a violent tornado.

Better examples for this argument are Grinnell and Lake City from this year, and Matador. All three of these inflicted violent damage without a doubt in my mind (Matador arguably inflicted full on EF5 damage for Pete’s sake) yet they were rated EF3. Sterling City potentially reached violent status as well, but I question the validity of that statement TBH.

Sterling city I argue had Ef5 winds, the contextuals weren’t as bad as Matador but were definitely “low end Ef5”.

Regarding Hollister/El Reno 2013, there has been many tornadoes that had deceitfully strong TVS but end up doing comparatively unimpressive damage at the surface.

In reality, tornadoes (particularly wedges) fail to develop a violent core, the vast majority of times a wedge just contains meso vortices; which can be strong in their own right (El Reno 2013 and Greenfield for example).

But due to the nature of meso vortices, the extreme velocities they achieve are simply too brief to do any real damage, which is why many tornadoes on radar look extreme on velocity but DOD is far less despite the fact.

Wedge tornadoes like Smithville, Bridge creek, Bassfield, Piedmont, (just to name a few) are examples of wedges that do contain a violent core, (which I would think looks like a secondary stove pipe shaped column hidden inside the main condensation funnel, that does the extreme damage).

It’s no coincidence that in violent wedges, the area of extreme damage looks like it occurred from a separate smaller tornado inside of the broad damage swath.

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.

This also isn’t a coincidence, violent cores likely do have weaker max wind velocities compared to meso vortices, but unlike those, violent cores are much larger in size and more importantly, last more than a second.

 

[Grand Poo Bah]

Here you go @slenker:

Yes, those are, indeed, fully debarked mesquite trees. Mesquite trees, for the record, are some of the most durable trees ever, and I believe I saw them mentioned as the poster child for "indestructible trees". It's apparently very hard to remove the bark even partially, and yet...

EDIT: I'm not even sure 30 seconds have passed and already 2 people have liked the post. Lol

Speaking of those mesquite trees. I posted my collages and descriptions to Reddit on Friday, and one comment was particularly attention grabbing. I'm definitely interested in your response.

"Bakersfield, Jarrell, Bridgecreek-Moore, El Reno-Piedmont, Chickasha, Goldsby and Moore 2013 would all like a word about Matador being the 'only tornado' to fully dbark and nub Mesquite. Bakersfield, Jarrell, El Reno-Piedmont and possibly Bridgecreek-Moore also have evidence of fully granulating entire Mesquites. Otherwise a good list, I would also add Stanton 2014."

 

[Lake Martin EF4]

Bakersfield, Jarrell, El Reno-Piedmont and possibly Bridgecreek-Moore also have evidence of fully granulating entire Mesquites.

If they do have evidence of that happening I've never seen it. Perhaps ask the commenter about it?

Also, there is photographic evidence that Jarrell scoured concrete. Even if it didn't obliterate mesquites, that's still insane, so the #10 spot on my list is justified.

 

[AJS]

If they do have evidence of that happening I've never seen it. Perhaps ask the commenter about it?

Also, there is photographic evidence that Jarrell scoured concrete. Even if it didn't obliterate mesquites, that's still insane, so the #10 spot on my list is justified.

It scoured the concrete foundation of a shed. Let me try and find the image.

 

[jiharris0220]

It scoured the concrete foundation of a shed. Let me try and find the image.

https://preview.redd.it/jarrell-1997-tornado-damage-v0-8jc7b0awf03d1.jpg?width=1080&crop=smart&auto=webp&s=772a1939f7d19a4fd28dc0bbb652dcff62615ea6

 

[AJS]

@Lake Martin EF4 Here ya go!

 

[AJS]

Redirect Notice

Reddit scares me lol. That place is ground zero for weather twitter type posters.

 

[jiharris0220]

Honestly looking back at the Jarrell damage photos, Im once again reminded how unthinkably violent this tornado was.

Obviously it’s a fool’s errand to deny that it’s extremely slow forward speed contributed to the damage quite a bit, but it’s pure r#&t$rd@*t+i%n to actually come to the conclusion that ef3 strength winds are capable of producing something like this in prolonged periods of time, like a certain engineering company in TX assumes.

 

[Grand Poo Bah]

Sterling city I argue had Ef5 winds, the contextuals weren’t as bad as Matador but were definitely “low end Ef5”.

Regarding Hollister/El Reno 2013, there has been many tornadoes that had deceitfully strong TVS but end up doing comparatively unimpressive damage at the surface.

In reality, tornadoes (particularly wedges) fail to develop a violent core, the vast majority of times a wedge just contains meso vortices; which can be strong in their own right (El Reno 2013 and Greenfield for example).

But due to the nature of meso vortices, the extreme velocities they achieve are simply too brief to do any real damage, which is why many tornadoes on radar look extreme on velocity but DOD is far less despite the fact.

Wedge tornadoes like Smithville, Bridge creek, Bassfield, Piedmont, (just to name a few) are examples of wedges that do contain a violent core, (which I would think looks like a secondary stove pipe shaped column hidden inside the main condensation funnel, that does the extreme damage).

It’s no coincidence that in violent wedges, the area of extreme damage looks like it occurred from a separate smaller tornado inside of the broad damage swath.

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.

This also isn’t a coincidence, violent cores likely do have weaker max wind velocities compared to meso vortices, but unlike those, violent cores are much larger in size and more importantly, last more than a second.

Just to add to this, it's worth noting the Doppler on Wheels study I'm constantly sharing in here concluded there's no correlation between Tornado width and wind speeds. Wide tornadoes are just as likely to have 200 mph+ winds as skinny ones.

However, I'm really starting to come around to the theory (first introduced in this thread ages ago by @slenker) that the reason skinnier tornadoes tend to have more extreme contextuals and more explosive damage, has more to do with pressure gradients than wind speeds. This would explain why the DOW (a tool for measuring wind speeds) was unable to find any differences in strength between the different sizes. 200 mph winds with explosive decompression, is going to look a lot worse than those winds without it. However, this theory doesn't account for slow movers like jarell that achieved those same explosive feats.

Lastly, I believe the reason a lot of huge wedges don't produce the damage you'd expect is because they aren't firmly planted on the ground. I've seen tons of videos where the base of the wedge appears to be 20-50 feet up and the only parts touching the ground are very short lived cyclical subvortices. I wish I could think of one of those specific videos so I could share an example. This would explain why the most violent wedges have long track cycloidal marks. They're firmly planted on the ground, and likely so are the subvortices within them.

 

[A Guy]

Sterling city I argue had Ef5 winds, the contextuals weren’t as bad as Matador but were definitely “low end Ef5”.

Regarding Hollister/El Reno 2013, there has been many tornadoes that had deceitfully strong TVS but end up doing comparatively unimpressive damage at the surface.

In reality, tornadoes (particularly wedges) fail to develop a violent core, the vast majority of times a wedge just contains meso vortices; which can be strong in their own right (El Reno 2013 and Greenfield for example).

But due to the nature of meso vortices, the extreme velocities they achieve are simply too brief to do any real damage, which is why many tornadoes on radar look extreme on velocity but DOD is far less despite the fact.

Wedge tornadoes like Smithville, Bridge creek, Bassfield, Piedmont, (just to name a few) are examples of wedges that do contain a violent core, (which I would think looks like a secondary stove pipe shaped column hidden inside the main condensation funnel, that does the extreme damage).

It’s no coincidence that in violent wedges, the area of extreme damage looks like it occurred from a separate smaller tornado inside of the broad damage swath.

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.

This also isn’t a coincidence, violent cores likely do have weaker max wind velocities compared to meso vortices, but unlike those, violent cores are much larger in size and more importantly, last more than a second.

The first bolded idea runs counter to the observed width/intensity relationship, and the second doesn't have any data behind it.

For making real time predictions of tornado intensity, both velocity of rotation and debris signature height have been found to have a direct relationship to surveyed damage.

 

[buckeye05]

It scoured the concrete foundation of a shed. Let me try and find the image.

That wasn’t the only concrete it scoured. There was a house with concrete walls and a foundation, including metal mesh reinforcement. The Jarrell tornado scoured the concrete down to the metal mesh. There are detailed close-up photos of this posted somewhere on the forum.

 

[AJS]

That wasn’t the only concrete it scoured. There was a house with concrete walls and a foundation, including metal mesh reinforcement. The Jarrell tornado scoured the concrete down to the metal mesh. There are detailed close-up photos of this posted somewhere on the forum.

Damn, I actually didn’t know that. Will definitely have to find that image to see what it looked like.

 

[jiharris0220]

The first bolded idea runs counter to the observed width/intensity relationship, and the second doesn't have any data behind it.

For making real time predictions of tornado intensity, both velocity of rotation and debris signature height have been found to have a direct relationship to surveyed damage.

Carful with the width/intensity relationship, I mean for one, maximum width definitely doesn’t always correlate to max intensity.

Although more importantly, the relationship obviously takes into account the maximum width, but by doing so, it ignores that the fact the area where extreme damage occurs is substantially smaller than the observed maximum width of damage.

Which again, is done by a violent inner core, it is a well known fact that wedge tornadoes, although rare, contain violent cores, which is responsible for the incredible feats of damage.

I need to make it clear though that meso vortices can in fact exhibit extreme damage cases, but again, in the vast majority of tornadoes, these meso vortices simply fail to produce any violent contextual damage due to their instantaneous nature.

For your second point, while there are/can be direct relationships which maximum TVS/debris height and actual DOD, in many cases, there’s simply no relationship. Although some of this can be contributed to the fact the tornadoes often peak in areas where radar beams can’t detect. (Grinnell is a recent example)

 

[Grand Poo Bah]

The first bolded idea runs counter to the observed width/intensity relationship, and the second doesn't have any data behind it.

For making real time predictions of tornado intensity, both velocity of rotation and debris signature height have been found to have a direct relationship to surveyed damage.

I also just recently learned about velocity signatures "folding" on radar. A lot of dopplers only have the capability of displaying up to 70 knot wind speeds in either direction on velocity. So when the winds exceed that, they move to the other end of the scale.

Here's an image of the 2020 Iowa derecho on velocities, taken by a radar to the east. The red indicates the wind is moving away from the radar, but that's obviously not the case, it's just the green was maxed out and continued through from the top of red. The dark green/gray areas inside the swath of red are spots where velocities moved all the way through red back into green. Which means the winds were over 140 kts (160 mph).



The most extreme tornadoes look so unintimidating on radar because their actual rotational wind speeds are in excess of 240 to 280 kts!

 

[tornado examiner]

Anyone else just keep going back to the Ashby dalton tornado and just wonder, what it would have looked like if it hit that farmstead directly with all the chasers nearby? What would that needle vortex sucking grass out by the roots have done to those farm buildings?
Would the vortex be too small and just cut them in half or something?

 

[slenker]

However, I'm really starting to come around to the theory (first introduced in this thread ages ago by @slenker) that the reason skinnier tornadoes tend to have more extreme contextuals and more explosive damage, has more to do with pressure gradients than wind speeds. This would explain why the DOW (a tool for measuring wind speeds) was unable to find any differences in strength between the different sizes. 200 mph winds with explosive decompression, is going to look a lot worse than those winds without it. However, this theory doesn't account for slow movers like jarell that achieved those same explosive feats.

Lastly, I believe the reason a lot of huge wedges don't produce the damage you'd expect is because they aren't firmly planted on the ground. I've seen tons of videos where the base of the wedge appears to be 20-50 feet up and the only parts touching the ground are very short lived cyclical subvortices. I wish I could think of one of those specific videos so I could share an example. This would explain why the most violent wedges have long track cycloidal marks. They're firmly planted on the ground, and likely so are the subvortices within them.

It wasn’t necessarily a theory, more like a hypothesis/conjecture, me throwing an idea out there. A theory would require me to conduct some intense research into that topic, preferably alongside or with the aid of actual meteorologists, and would have to be backed up quite substantially. It would have to stand up to strutiny and make accurate predictions. This isn’t my field so I’m not going to claim anything too brashly, and I’m not going to do any said of this sort of research in the first place.

I recall seeing someone here state there’s at least one paper showing that the pressure gradient has little to no effect on damage because it simply isn’t a powerful enough event, even in violent tornadoes, to attribute to damage the winds are going to do. I would believe it. It’s simply not enough of a pressure drop to aid greatly in that department, I imagine. I’m not a meteorologist, or a wind engineer, or an expert on fluid dynamics, though, so take what I say with a grain of salt if I’m making those predictions. I enjoy making some of my own and thinking about how these things work, and sometimes I just air it out lol

 

[jiharris0220]

This paper which talks about the Garden City KS tornado describes what Im trying to convey nicely.

The Garden City, Kansas, Storm during VORTEX 95. Part II: The Wall Cloud and Tornado

Abstract On 16 May 1995, a supercell storm produced an F1 tornado near Garden City, Kansas, during VORTEX (Verification of the Origins of Rotation in Tornadoes Experiment). This event provided the first opportunity to synthesize data collected by a new airborne radar platform called ELDORA...

journals.ametsoc.org

Particular figure 6, explaining swirl ratio dynamics.
My point regarding that in wedge tornadoes, the vast majority of the time, vorticity is broken down into meso vortices that rotate around a central axis, (the parent funnel). This is the structure within most tornadoes, which is why damage ends up paling in comparison to observed extreme radar velocities.

The part that I highlighted is what Im talking about with the rare breed of wedge tornadoes that manage to balance out wind shear (horizontal winds) and updraft (vertical motion) to create a singular vortex within the parent wedge funnel.

This is what I mean by a violent core, and this is where the extreme damage in wedges come from, not the actual parent funnel itself.

I’ve never seen a case where the outer parent funnel (the wedge) produce any impressive damage by itself. The extreme damage always comes from either an inner core, or more oftenly but still rare, meso vortices that actually manage to cause violent damage.

 

[TH2002]

I'd actually love to hear what about the survey specifically is nitpicked and badly done, if you have the time to go over it. I definitely believe it considering certain offices and how they conduct surveys. Like, what specifically makes the nitpicking they did "pedantic" or unnecessary? I don't think I've ever seen imagery of the damaged homes from Chapman before either so I can't make any specific remarks about it myself. Was it anchor bolted?

A few days late to this, but to answer your questions...

Yes. Two of the homes Chapman swept away were anchor bolted.

Regarding why the survey was pedantic, I'm just gonna quote @buckeye05 since he explained better than I could:

Reasons for downgrade:
-Not a totally clean sweep

Reasons for upgrade:
-Poured concrete foundation
-Anchor bolts, which were bent
-Sill plates splintered
-Reinforced concrete stem wall torn away from basement foundation
-Subfloor missing
-Extreme damage to cars, farm machinery, and trees on the property.
-Railroad tracks bent nearby.

Keep in mind the list above only applies to the one brick farmhouse that was swept away. The other anchor bolted house wasn't even surveyed.

 

[Grand Poo Bah]

I’m not a meteorologist, or a wind engineer, or an expert on fluid dynamics, though, so take what I say with a grain of salt if I’m making those predictions.

You're studying physics though, right? May be a good topic for a thesis way down the road! Lol.

Here's a really interesting study with some equations for calculating the pressure change inside of tornadoes. The max wind speed they used for their calculations was 100 m s (224 mph) and the resulting pressure change was 10,000 kpa (10% change from sea pressure). I'd be really curious what the result would be with an input of 142 m s (318 mph), or even 116 m s (260 mph). That'd cover the legacy F5 range.

15.4: Tornadoes

Tornadoes are violently rotating, small-diameter columns of air in contact with the ground. Diameters range from 10 to 1000 m, with an average of about 100 m. In the center of the tornado is very low …

geo.libretexts.org

The study is another example of institutions using EF scale derived wind speeds to make calculations instead of real, measured wind speeds. They considered the pressure change negligible because only .1% of tornadoes approach those speeds according to the EF scale, when the DOW team has proved it's actually over 5%. How much more significant would that pressure change be if they knew it was relatively common? Would it have warranted further study? How significant was the pressure change in the Smithville tornado which was moving at 60 mph and likely had 320 mph+ winds?

Just another example of how the EF scale is harming science.