Enhanced Fujita Ratings Debate Thread

[Grand Poo Bah]

Here’s a more formal thread on the calculation of wind speeds near the surface in tornadoes from cycloidal markings/scattering in fields. Seems to certainly have some promise.

Evaluating the Viability of Surface Marks to Estimate Tornado Winds in Rural Areas

Tornadoes cause significant damage, injuries and fatalities worldwide. Tornado-based design for structures was introduced in ASCE 7-22, and design for tornado loading will continue to become more common in tornado prone regions and for certain structures in the United States. One parameter used...

ui.adsabs.harvard.edu

Wow! This is fascinating. It was Published almost two years ago. I wonder why the Washington, IL tornado still hasn't been upgraded.

An average of all the wind speeds for each individual loop was calculated to obtain the estimated wind speed for that section of the track. From the cycloidal surface marks, the Washington tornado had an average wind speed estimate from as low as 184 mph to as high as 219 mph across multiple areas of its path. The high wind area had individual surface mark wind speeds from 205 mph to 231 mph in addition to limitations with the accuracy of loop width and height measurements. Estimates of wind speed were then compared with wind speed estimates using the EF scale from nearby structures. The peak wind of 219 mph occurred immediately after Washington, IL and a residential neighborhood.

 

[SouthFLwx]

Also in Dawson Springs the tornado quite suddenly intensified as it crossed the eastern side of town producing relatively extreme damage,

View attachment 47224View attachment 47225

Higher end of vegetation damage, with some debarking and rootballing. This is probably a bit easier in a densely populated area though.

View attachment 47226

There was a small industrial district right on the edge of town. Multiple larger buildings were destroyed here.

View attachment 47227
View attachment 47228View attachment 47229

Debris was once again granulated and wind rowed, and trees were mangled - as was common with this tornado throughout the track.

View attachment 47230

The NWS used 2 EF4 DIs in the town, the highest being 180mph, however you can see on DAT they missed numerous structures.

View attachment 47231

If you watch the aerial damage videos there are so many slabs where homes are almost completely covered in debris from other structures to the point they aren't visible. I don't find it impossible to think there may have been one home perhaps well built enough for an EF5 rating that was not surveyed, but there was also plenty of very subpar construction used. It's just one of those things where I think we will never know.

Also in my personal opinion, when tornadoes move through densely populated areas, especially quickly - the pure abundance of debris makes it harder to achieve the granulated, wind rowed, slab swept clean look so the tornado looks less intense (similar occurred in Rolling Fork and Greenfield). That's partly what makes tornadoes like Moore and Smithville (you could even argue Washington, IL) so extremely impressive when they completely swept clean almost all debris in the areas they impacted.

I think you make alot of great points here. Dawson Springs has some of the worst damage along the tornado’s track and is definitely close to EF5 intensity. The mass devastation and complete destruction of neighborhoods is definitely what leads me to believe that the damage is more consistent with a high end EF4 (190-200 mph). Also yeah, the survey here wasn’t the best and likely had to do with the fact that NWS Paducah had so much damage to survey along the tornado’s track. Also glad you brought up Washington 2013 because that one should have been an EF5.

 

[AJS]

Pretty wild stuff while it was traversing the distance between Cayce and MayfieldView attachment 47233View attachment 47234View attachment 47232

Jeez, i’ve never really seen the damage from the beginning of its path, that is some pretty gnarly tree damage.

 

[WeathermanLeprechaun]

It's not just Vilonia and Mayfield. There's a ton more. So much more. Listing just from structural damage alone:

Louisville the day after Vilonia
Pilger family later that year (at least 3 EF5 candidates)
Rochelle 2015
Holly Springs 2015 (New Wren reborn)
Chapman 2016 (rock solid EF5 DI)
Canton 2017 (maybe?)
Camp Crook 2018
Bassfield 2020 (Evidence seems to be piling up for an EF5 at the cabin)
Rolling Fork 2023 (Likely EF5 at Family Dollar)

Not even including likely contextual EF5s like Cisco, Monette or Matador.

So, yea

Those are the most POPULAR candidates of mine. Most of yours i agree with, and others i just don't know enough about their particular insights of damage to argue against (I know Camp Crook was pretty gnarly contextually, but i forget the real specifics)

Regarding Pilger, Rochelle and Holly Springs, I agree on the first two but Holly Springs I've always seen as a strong candidate, just nothing too concrete to justify my opinion
Some of the damage I've seen with Chapman on this forum certified it as so because even Topeka went ahead and said it would've been a EF5 had it stuck HEAD ON
Canton, eh, I'm not too sure on it. Probably mid end-high end EF4 based on contextuals, but was structural damage that pristine to say so?
Camp Crook like I've said was pretty vicious but it's one of those cases I'd have to look back over
Bassfield, with the new rules, this is increasing, so I'm leaning on yes here
Rolling Fork: i have no doubt this was a EF5 but the Family Dollar is so borderline, I'm not sure because some Jackson surveyor made a comment about it and it got misinterpreted a bit

 

[Ozonelayer]

To think all of this re-evaluation is due to NWS Grand Forks and the first EF-5 in 12 years.

Anyway, here are EF-5 candidates based on how confident I am that they should be rated EF-5 in no particular order.

High Confidence:

Mayfield
Vilonia
New Wren
Tuscaloosa
Chickasha
Goldsby
Ringgold
Chapman

Low-Medium Confidence:

Bassfield-Soso
Rolling Fork
Tri-State '21
Matador
Rochelle-Fairdale
Holly Springs

Honorable Mentions:
Diaz
Greenfield
Probably a few others Im forgetting.

 

[tornado examiner]

To think all of this re-evaluation is due to NWS Grand Forks and the first EF-5 in 12 years.

Anyway, here are EF-5 candidates based on how confident I am that they should be rated EF-5 in no particular order.

High Confidence:

Mayfield
Vilonia
New Wren
Tuscaloosa
Chickasha
Goldsby
Ringgold
Chapman

Low-Medium Confidence:

Bassfield-Soso
Rolling Fork
Tri-State '21
Matador
Rochelle-Fairdale
Holly Springs

Honorable Mentions:
Diaz
Greenfield
Probably a few others Im forgetting.

Remember how well build the homes slabbed by the goldsby tornado were? Some of them had anchor spacing well above what it typically seen. Shooting those homes into the upper bound territories of that DI.
All of them should qualify as EF5 indicators yet they were all under-rated. Siiigh.

 

[tornadowatch211]

Found this aerial of Enderlin that seals it as an EF5: youtu.be/ilfQat2RvrU. Two snippets are below. Note the absurd tree damage, especially in the top image.

 

[Kds86z]

 

[joshoctober16]

It's not just Vilonia and Mayfield. There's a ton more. So much more. Listing just from structural damage alone:

Louisville the day after Vilonia
Pilger family later that year (at least 3 EF5 candidates)
Rochelle 2015
Holly Springs 2015 (New Wren reborn)
Chapman 2016 (rock solid EF5 DI)
Canton 2017 (maybe?)
Camp Crook 2018
Bassfield 2020 (Evidence seems to be piling up for an EF5 at the cabin)
Rolling Fork 2023 (Likely EF5 at Family Dollar)

Not even including likely contextual EF5s like Cisco, Monette or Matador.

So, yea

as for cisco 2015

here are some images






vehicles and farm equipment were tossed more than 1 mi (1.6 km)

 

[buckeye05]

To be fair the bolts had to have been connected to the attached MBS to the northwest of the main church, that was an entirely separately rated building, those don't fit anywhere on a masonry church while also being connected to a concrete slab. Also for the Marshall rating, the wording says/leads me to believe that the 170mph rating was a preliminary assessment as to what is needed at the very minimum to destroy a large church such as this, even at lower bound, instead of a flat rating of the entire building. The current CARB DI is now max DOD LB 175, close to the 170 mentioned in the paper. Newer information than the Marshall paper states clearly that this building was definitely above the threshold of 170mph.

That’s a good point, at least in terms of the pics with the badly rusted anchor plates, because as you mentioned those anchored the newer metal framed addition to the church, rather than the brick chapel itself. With that said, the super long rusty anchor bolt pictured actually does appear to have been part of the chapel, but it doesn’t look to be too badly corroded so I think your point still stands. Overall, I still can’t confirm this church as a 100% slam dunk EF5 damage point just by looking at it, but I am no way ruling it out as a strong EF5 candidate either. Unfortunately that’s about as definitive as I can get. Like I said, I think there’s something somewhere along Mayfield’s path that can be used to get this tornado the EF5 rating it deserves, but what specifically remains to be seen. It may very well come down to something like root ball displacements.

I thought the church was rated 188. Also this survey seems to assume a much smaller building than actually destroyed. That church was massive, and I doubt you"re sweeping it clean with anything less than 300+ winds.

No, that was the Mayfield First United Methodist Church with the 188 MPH estimate. The church being discussed here is the Mayfield First Presbyterian Church, which is absent from the DAT but is included in Tim Marshall’s survey, albeit with a suspiciously low wind speed estimate.

Hmmmm...

@buckeye05, does this information change things related to your opinion on the cabin?

Perhaps my biggest issue with the Bassfield cabin is something nobody here has mentioned. Yes there’s the vehicle impact issue and other stuff, but the other major problem was the fact that it lacked external sheathing. I know that doesn’t sound like a big deal, but it is from a wind resistance standpoint. I actually know of a case where an entire multi-story apartment building under construction collapsed during some pretty tame straight-line winds because the construction crew hadn’t installed sheathing yet. Its absence really can render a building vulnerable, even if the anchoring and roofing is solid.

BUT…with all that said, given Jim LaDue’s much less conservative, “it doesn’t have to be a fortress” approach to defining EF5 house damage as of late, the bar is lower now, so that’s the approach I am taking now. There’s a lot of contextual evidence to suggest that the Bassfield tornado reached EF5 intensity at and around that cabin (I actually believe it maxed out right after hitting the cabin). So given the lowered bar for EF5 criteria and what appears to be a “just call it it like it is” approach being promoted, I’m calling it like it is: Bassfield was an EF5 and I think the rating should reflect that, even while acknowledging that the cabin could have been built with sturdier walls and likely suffered a vehicle impact.

 

[buckeye05]

To think all of this re-evaluation is due to NWS Grand Forks and the first EF-5 in 12 years.

Anyway, here are EF-5 candidates based on how confident I am that they should be rated EF-5 in no particular order.

High Confidence:

Mayfield
Vilonia
New Wren
Tuscaloosa
Chickasha
Goldsby
Ringgold
Chapman

Low-Medium Confidence:

Bassfield-Soso
Rolling Fork
Tri-State '21
Matador
Rochelle-Fairdale
Holly Springs

Honorable Mentions:
Diaz
Greenfield
Probably a few others Im forgetting.

I’m surprised to see Ringgold that high. Has there been more information dug up that makes a strong case for EF5? I don’t doubt that it was one, but I’ve always thought the focus was on the Cherokee Valley area (I think) outside of town where that cluster of homes was obliterated. NWS Peachtree reportedly said they were poorly anchored. Then again…it’s early 2010s NWS Peachtree City, and they put out quite a few questionable surveys back then.

Anyway, I assume there was there some crazy contextual damage or vehicle lofting that I never heard about? Or Mayr other homes elsewhere along the path that were EF5 candidates?

 

[Lake Martin EF4]

I’m surprised to see Ringgold that high. Has there been more information dug up that makes a strong case for EF5? I don’t doubt that it was one, but I’ve always thought the focus was on the Cherokee Valley area (I think) outside of town where that cluster of homes was obliterated. NWS Peachtree reportedly said they were poorly anchored. Then again…it’s early 2010s NWS Peachtree City, and they put out quite a few questionable surveys back then.

Anyway, I assume there was there some crazy contextual damage or vehicle lofting that I never heard about? Or Mayr other homes elsewhere along the path that were EF5 candidates?

One home on Cherokee Valley was indeed well anchored and completely obliterated, and according to @TH2002 it then met EF5 structural and contextual criteria again in Tennessee.

 

[andyhb]

Uh oh.

 

[Grand Poo Bah]

Uh oh.

They calculated the grain cars that were drug along until they were perpendicular with the rest of the train 230 mph, so I think the rating is still safe lol.

Plus like, who would expect a cylindrical object thrown 400 feet to NOT roll a little ways after landing?

 

[Ozonelayer]

Uh oh.

Given the lack of a longer trail in other images, and the fact that it is barely visible, and the shape, I think it landed after being tossed ~400 ft then rolled a couple yards. Not unlike a cylinder to do. This is also pointed out in the comments of that post (albeit not how I explained it but still similar.)

Ples the other grain cars were calculated at 230 MPH, so I think the rating won't change.

 

[slenker]

The only thing this is likely to change is the NWS’s unofficial intensity of >266 MPH. That number is incredibly bullish in general anyways. In my eyes this is still absolutely an EF5 tornado and if they change it to an EF4 it would be atrociously bad.

 

[wolfywise]

Uh oh.

He's mistaking till lines for drag marks. Look behind the tanker. If this was actually rolled you'd see way more prominent gouges in the soil that line up with the kibble covering the tanker.

 

[tornado examiner]

Are people now seriously trying to call into question the feats and intensity of this tornado solely because it is the first EF5 in 12 years…
WHO DOES THAT!? Bruh.
They weren’t doing that before it was rated EF5.

 

[WeathermanLeprechaun]

Uh oh.

With how violent Enderlin was, there's no doubt that the car would've been viciously slammed and alone with the force, would've rolled a bit. It was still lofted briefly, but I'm not sure what he's suggesting here either. This doesn't change much to the rating imo, but probably gives me some suspicion the >266 estimate is a bit bullish. Their estimate of 230 is completely fine imo given this

 

[tornado examiner]

There is literally zero reason to try and get this lowered in any capacity. Especially when your evidence against it is dubious at best. Even if it wasn’t fully thrown it was still airborne for some time.