Enhanced Fujita Ratings Debate Thread (1 Viewer)


pohnpei

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Today NWS Nashville has just released pictures of all 26 EF4 rating postion of cookeville tornado, actully most of these EF4 damage houses were well constructed residence, some being metioned had J bolt and some was attached to the foundation very well. Most of them swept clean as we all can see easily. For dayton tornado last year on 5/27 earned 170mph without EF4 structure damage and this one get 175mph with tons of well constructed FR12 residence swept clean, the inconsistency among different NWS was just such great.
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Equus

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I've gotten to the weird point where I'm so relieved to see a WFO rate obvious violent damage as violent (more often than not, mid EF3 is absolute tops) that I won't even argue too hard for an even higher rating up the violent scale. Given the anchor bolts present in some of the pics, and the death ratio, Cookeville was obviously more violent than a decent chunk of F5 rated tornadoes on the historical record, but as we all know, the more stringent criteria of the last 18 years or so has rendered historical comparisons moot. It is more violent than many official EF4s but I don't see too much that would confidently push it higher.

The main factor limiting EF5 according to some discussions I've seen is the probability that chunks of less well constructed homes were thrown at the bolted ones, compromising their integrity; while this is very likely, it still seems nit-picky, and seems to be a way of saying "no home damage will ever be rated EF5 again unless it's completely isolated from any other structure or debris source AND well above official state construction code" which seems exceptionally arbitrary and nigh impossible. Slabbed well constructed homes has always been an F/EF5 hallmark and there's no reason to hold that to excessive conditions - it's just a six point scale used to file events away, not something that should be overly complicated.

I WILL say, that while the structural damage at Cookeville is significantly worse than at Beauregard imo (and is vastly worse than Dayton) and tree damage screams violent, contextual factors don't impress me as much as our more recent EF5s and even some high EF4s; Vilonia having worse scouring and debarking and even cleaner slabs/higher death toll, and Chapman/Beauregard had far higher end vehicle damage. If those tornadoes weren't rated EF5 (though Vilonia objectively should have been) then the contextual factors would seem to limit this to mid EF4. Given those contextual factors, I'm fine with the rating despite severe slabbing.

And as bad as Cookeville was... incredibly, it was almost significantly worse. Thank exceptionally rapid dissipation.

baxtercookevilletormap~2.jpg
 

buckeye05

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Equus said it perfectly. The number of slabbed, anchored homes does raise an eyebrow, but contextual evidence for EF5 is glaringly missing. There was no extreme debarking, scouring, or vehicle damage in this tornado. While some of these things are present, its not what you’d see in an EF5. Also, the debris patterns weren’t overly impressive (EF5 typically has a finely granulated “explosive” look to it). Overall, I’d say EF4 is very much appropriate, and I can say with a high degree of confidence that this wasn’t an EF5. Keep in mind that EF5 is for the absolute most violent, extreme damage possible. The Cookeville damage doesn’t quite fit that category. Also keep in mind that there is clear evidence of debris cleanup in these pics.

Only thing is I would have gone with a slightly higher wind speed estimate if it were up to me.
 

buckeye05

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Here's something that I see in damage surveys that always irks me. It's become clear to me that certain WFO survey teams do not have a good grasp on the varying degrees of tree damage. The Cantril, IA EF3 tornado from 05/27/2019 is a perfect example. Surveyors called this EF3 tree damage, which is defined as severe debarking with only stubs of largest branches remaining. This tree is not debarked or denuded. Not even a little bit, but they went with EF3. Then on the other end of the spectrum, sometimes you will see severe actual debarking rated EF2. I hate to question professionals, but when I see stuff like this, I have to ask "Do you guys really know what you're doing here?" Is it possible that some surveyors aren't clear on what actual debarking looks like? I really can't help but think that might be the case sometimes.
 

Lori

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The Cookeville, TN damage looked a lot like Tuscaloosa, AL EF-4 on April 27, 2011 IMO
 

buckeye05

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A reminder that Vilonia should've been an EF5.
This is all on a certain someone. He allowed personal bias to get in the way of the official documentation of a historic, first time in history event. Still never going to get over that. Shameful. The reasoning used to justify his decision has been shown to be a farce over and over again via more recent events.
 
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Equus

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I fear Vilonia is what set the unfortunate precedent of nit-picky lowballing. Obviously haven't seen very many EF5 candidates in recent years but since then, leveled houses being rated EF2 for example is happening waaay more than it oughta.

I'm sure that same met, if in charge of the NHC, would have held Michael at a category 3 because of "precedent" for landfalling east Gulf hurricanes despite sanity and all available data
 

buckeye05

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I fear Vilonia is what set the unfortunate precedent of nit-picky lowballing. Obviously haven't seen very many EF5 candidates in recent years but since then, leveled houses being rated EF2 for example is happening waaay more than it oughta.
This is what I mean about the damaging precedent this sets. It inadvertently has created a situation where WFOs are second guessing their decisions, and that spirals into a situation where we're back to 2006 and previous. The Vilonia rating decision had a massive, negative impact on the rating system and its shameful. End of story. Bassfield has the chance to correct this. We'll see what happens.
 

Equus

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Yep... extraordinarily frustrating. Having seen WFOs actually break the LB constraints to underrate a tornado on multiple occasions after that I don't have much faith in ratings past early 2014. Can think of a bunch of EF4s from 2007-2013 that'd be lucky to get low EF3 now.
 
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I have seen some tornadoes be overrated. The Rozel tornado in 2013, one in Iowa in 2013, and one last year in Ohio. They were all rated EF4 but didn't seem like they were any higher than high-end EF2 or low-end EF3.
 

buckeye05

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I have seen some tornadoes be overrated. The Rozel tornado in 2013, one in Iowa in 2013, and one last year in Ohio. They were all rated EF4 but didn't seem like they were any higher than high-end EF2 or low-end EF3.
I live in Dayton, and I know the tornado you are referring to. Was mainly rated EF4 based on tree damage. I surveyed that section of the path on my own time and found unbelievable debarking, but no EF4 structural damage. The most intense winds funneled into a river valley behind an apartment complex, so the EF4 winds only affected trees. I actually agree that it was a marginal EF4, but was shocked to see they rated it as such.
 

Equus

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Dayton definitely surprised me as it's one of the few violents I don't feel were rated unusually conservatively. Unless I'm wrong I think Rozel was rated due to a DOW measurement, the same kind of thing that other WFOs either embraced fully or completely disregarded in the two weeks following... which throws off rating consistency in the other direction
 
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I live in Dayton, and I know the tornado you are referring to. Was mainly rated EF4 based on tree damage. I surveyed that section of the path on my own time and found unbelievable debarking, but no EF4 structural damage. The most intense winds funneled into a river valley behind an apartment complex, so the EF4 winds only affected trees. I actually agree that it was a marginal EF4, but was shocked to see they rated it as such.
I sometimes wish there was a higher DI on tree damage. Like when trees are completely stripped of all bark and even the smallest twigs are even debarked. Also when low lying shrubs are completely debarked or torn out of the ground by their roots.
 
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I live in Dayton, and I know the tornado you are referring to. Was mainly rated EF4 based on tree damage. I surveyed that section of the path on my own time and found unbelievable debarking, but no EF4 structural damage. The most intense winds funneled into a river valley behind an apartment complex, so the EF4 winds only affected trees. I actually agree that it was a marginal EF4, but was shocked to see they rated it as such.
I never saw that tree damage in Ohio. Do you have pictures of it?
 

Equus

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Yeah there's definitely a difference in vegetation between debatably EF3/low EF4 and slam dunk EF5. Am a big time tree/ecology nerd so always look into vegetation damage after high end tornadoes, and low-lying vegetation and hardwood tree bark could join vehicles as being EF5 vs marginal EF4 differentiators
 
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Yeah there's definitely a difference in vegetation between debatably EF3/low EF4 and slam dunk EF5. Am a big time tree/ecology nerd so always look into vegetation damage after high end tornadoes, and low-lying vegetation and hardwood tree bark could join vehicles as being EF5 vs marginal EF4 differentiators
Speaking of vehicles were there any that were completely mangled beyond recognition in this recent outbreak. For example such as the Ford Explorer in Smithville, MS on April 27, 2011, the truck in El Reno on May 24, 2011, or the Suburban in Vilonia on April 27, 2014.
 

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