Enhanced Fujita Ratings Debate Thread

[TH2002]

I just don't know what they're looking at to say this was a high end EF4

It's what they're not looking at. The survey in Cambridge Shores makes ZERO mention of the homes that were slabbed at 176 Kentucky Avenue or 583 Sherwood Drive but it would be a waste of time to mention them to Paducah because they would probably nitpick them anyway even if they were of "superior" construction.

 

[TH2002]

its a preliminary rating....but people are saying it could remain that way. and if it does....we'll probably pester them into upgrading it to an EF-5. we all know it was an EF-5 with strength to rival smithville 2011. their rating is irrelevent if they keep it as an EF-4. cause its just objectively false. idc what they say at this point. the EF-scale is broken and they're crap at their jobs.

They don't care what a few weather nerds think. They wouldn't care what a hundred professional storm chasers and meteorologists think, let alone some weather nerds on a site like TalkWeather.

I honestly think part of it is spite towards people like us because they have gone out and said "Naw, it's just a high end EF4 cause we said so" after the entire meteorological community had pretty much deemed it to be an EF5. The exact same thing happened after the Tuscaloosa tornado in 2011.

 

[Tomcats Forever!]

If Mayfield isn't upgraded, maybe they should just make it official and make EF-4 the open ended peak of the scale... ypu know, if that wouldn't further encourage some offices to rate EF-4 damage as EF-3...

 

[TH2002]

If Mayfield isn't upgraded, maybe they should just make it official and make EF-4 the open ended peak of the scale... ypu know, if that wouldn't further encourage some offices to rate EF-4 damage as EF-3...

Might as well since an EF5 is pretty much impossible to achieve these days.

 

[TH2002]

NWS Paducah: EF5? What the hell is this? The hypothetical tornado that Fujita said was not possible or evacuate immediately due to radiation contamination as the area was nuked by Iran.

 

[locomusic01]

I don't remember who it was now, but someone on Twitter yesterday reminded me of the piece Chuck Doswell wrote over a decade ago, around the time the EF-scale was being implemented. As usual, Chuck was pretty prescient:

a. Damage "indicators"
An important part of this suggested revision of the Fujita Scale is the notion of damage indicators. The participants in the process of "enhancing" the Fujita scale were polled to provide what they subjectively felt were "indicators" of the windspeeds in tornadoes, to add new indicators beyond the "well-constructed" frame home that formed the basis for Fujita's F-scale. The synthesis of that input was an "enhanced" list of damage indicators that would allow the members of a local NWS survey team to make estimates of the windspeeds associated with an observed level of damage. Notably, the windspeeds associated with the high-end indicators, including "well-constructed" frame homes were revised substantially - downward. The details are contained in the documented indicators (see here for the PDF), but an important issue is that according to the current list of EF damage indicators, it's impossible for any damage to a well-constructed frame home to be associated with an EF-5 rating. Contrary to what I was told during the initial meetings concerning the development of the EF-scale, this would mean a notable change in the ratings. Under the old F-scale criteria, if a well-constructed frame home was swept away, leaving nothing but a foundation and no standing walls, then that would be considered F5 damage. Under the new EF-scale system, that would no longer be true - the highest possible rating by the new EF-Scale standard would be EF-4. Only if the structure of a standard frame home was somehow enhanced beyond standard practice throughout the load path, would it be possible for EF-5 damage to be inferred from frame home damage. This amounts to a change to the ratings, and would imply that any F5 rating in the past was, in effect, not valid. I see this as an important violation of I was led to believe was the agreed-upon constraint that any new rating system would not result in a change to the ratings of the past.

EF scale diatribe

And this is pretty much what we've seen play out. It's been clear for many years now, obviously, but high-end EF4 has effectively become the default maximum rating. The only possible exception is if a survey team gives due consideration to contextual damage, which seems to have become less and less common.

In a vacuum, it doesn't really matter. I sort of mentally group tornadoes into "strong" (roughly corresponding to EF3 to low-EF4), "violent" (mid-EF4+) and "holy $@&%" (historically violent) anyway. But it isn't in a vacuum, and this shift has really blown to shreds any remaining semblance of consistency with the historical record. We've basically entered the equivalent of baseball's dead-ball era in terms of high-end ratings.

This isn't anything we didn't already know, but I think it would be helpful if it were officially acknowledged instead of carrying on as if nothing has really changed.

 

[atrainguy]

This is probably all old news, but I saw this post on Twitter that affirms the revision of the EF scale is indeed still coming. In the comments, he mentions some of the new damage indicators that would probably be added alongside the current ones.

 

[warneagle]

I hope this means they're doing more experimental work to try to empirically validate the correlations between the DIs and predicted wind speeds. If they can show their work and use that data to develop a more methodical, consistent approach to damage assessment, then I think people would have a lot less room to complain about ratings.

As far as historical comparisons go, I don't know how they could possibly rectify the current scale with the pre-2007 Fujita scale, since we know the wind speeds were completely unrealistic and surveying was even more inconsistent than it is now; in fairness to the current assessors, there would never be a case like Belmond or Broken Bow where F5 ratings were assigned based on one or two houses that were obviously not properly anchored. Obviously this is annoying in terms of assessing long term trends with respect to significant/violent tornadoes before 2007, but I don't know how they could fix that other than retroactively giving EF ratings to those older tornadoes, which is impractical if not impossible.

 

[Equus]

Grazulis has essentially re-rated every significant tornado he felt was inappropriate in his Significant Tornadoes volumes, it can definitely be done but took thousands upon thousands of hours and crossing the country endless times squinting at microfilm to do. Perhaps we should use Grazulis' much more exhaustively researched ratings for pre 2007 as his work removes most of the egregious violent ratings of the distant past

 

[warneagle]

Grazulis has essentially re-rated every significant tornado he felt was inappropriate in his Significant Tornadoes volumes, it can definitely be done but took thousands upon thousands of hours and crossing the country endless times squinting at microfilm to do. Perhaps we should use Grazulis' much more exhaustively researched ratings for pre 2007 as his work removes most of the egregious violent ratings of the distant past

Yeah if Grazulis disputes a rating I'm generally inclined to side with him. I also generally tend to side with Fujita's initial ratings on some of the pre-1970s tornadoes, especially the Palm Sunday Outbreak where tornadoes he rated F5 were later downgraded for no good reason, which is even more frustrating when much more questionable pre-1970 F5s like Vicksburg and Belmond were allowed to stand.

 

[Equus]

Yeah if Grazulis disputes a rating I'm generally inclined to side with him. I also generally tend to side with Fujita's initial ratings on some of the pre-1970s tornadoes, especially the Palm Sunday Outbreak where tornadoes he rated F5 were later downgraded for no good reason, which is even more frustrating when much more questionable pre-1970 F5s like Vicksburg and Belmond were allowed to stand.

Seems like inconsistency has been a problem since the whole inception of the initial scale lol. I very much like having one neutral party catalogue things to remove wfo to wfo bias and the shifts over time in strictness, but I wouldn't curse any one person with the massive and immensely commendable effort he's went through to arrive at that point

 

[warneagle]

Seems like inconsistency has been a problem since the whole inception of the initial scale lol. I very much like having one neutral party catalogue things to remove wfo to wfo bias and the shifts over time in strictness, but I wouldn't curse any one person with the massive and immensely commendable effort he's went through to arrive at that point

Yeah, it would be nice in theory to have like, a dedicated group of personnel who travel and do all the surveys rather than leaving it up to each WFO, but I don't know if that would really be practical or not. It would eliminate the ambiguity but they'd also have weeks to months of down time each year outside the active season. Getting paid to do nothing a few weeks a year sounds like a great job to me, but the NWS might disagree.

 

[Equus]

Yeah, it would be nice in theory to have like, a dedicated group of personnel who travel and do all the surveys rather than leaving it up to each WFO, but I don't know if that would really be practical or not. It would eliminate the ambiguity but they'd also have weeks to months of down time each year outside the active season. Getting paid to do nothing a few weeks a year sounds like a great job to me, but the NWS might disagree.

Would be pretty ideal honestly, though might also run into trouble convincing the powers that be that the issue is so significant and meaningful that the system should be changed even in comparison to all the other issues goin' around; it's a very vexing and major issue in the realms of wind engineering and severe wx sure but on that sort of scale we'd have to have some super public controversy for change to likely happen

 

[Austin Dawg]

This is probably all old news, but I saw this post on Twitter that affirms the revision of the EF scale is indeed still coming. In the comments, he mentions some of the new damage indicators that would probably be added alongside the current ones.

Does this mean Jarrell, Smithville, Hackelburg, and the old top F5's go to F6? F5+?

Or do we get F4.1, F4.2, F4.3... etc?

 

[A Guy]

The American Society of Civil Engineers were the ones who proudly claimed there was no EF-5 damage in Joplin. I bet what they'd come up with is ultra conservative and produces lower ratings.

No update to the EF scale can solve the main problem of application, which is the abuse of the lower bound value, and it can't solve shoddy surveying.

Still waiting for a photogrammetry study of low-level winds.

 

[locomusic01]

It seems to me the fundamental problem is a shift in the intended purpose of tornado ratings. The original purpose was to use the damage produced by a tornado to infer its likely intensity. Somewhere along the way, that purpose essentially shifted to analyzing the minimum verifiable intensity needed to produce the observed damage.

And on one level, I get it. That approach is probably the best way to enforce consistency and scientific rigor (at least in theory). But it also means you're deliberately no longer trying to assess how strong a tornado actually was. In effect, what you're doing is surveying construction practices. That's undoubtedly important information to have, but it's not what an EF rating is intended to represent. And when we already have enough data to know that we're significantly underrating tornadoes in general, all this approach does is exacerbate the problem.

 

[Shakespeare 2016]

The American Society of Civil Engineers were the ones who proudly claimed there was no EF-5 damage in Joplin. I bet what they'd come up with is ultra conservative and produces lower ratings.

No update to the EF scale can solve the main problem of application, which is the abuse of the lower bound value, and it can't solve shoddy surveying.

Still waiting for a photogrammetry study of low-level winds.

A 175 mph EF4 for a house that was swept away and the walls blown out. This came from NIST and ASCE.

 

[A Guy]

It seems to me the fundamental problem is a shift in the intended purpose of tornado ratings. The original purpose was to use the damage produced by a tornado to infer its likely intensity. Somewhere along the way, that purpose essentially shifted to analyzing the minimum verifiable intensity needed to produce the observed damage.

And on one level, I get it. That approach is probably the best way to enforce consistency and scientific rigor (at least in theory). But it also means you're deliberately no longer trying to assess how strong a tornado actually was. In effect, what you're doing is surveying construction practices. That's undoubtedly important information to have, but it's not what an EF rating is intended to represent. And when we already have enough data to know that we're significantly underrating tornadoes in general, all this approach does is exacerbate the problem.

It feels like to me that the EF scale has been designed and even more markedly implemented to fit the desires of engineers, looking at it from a purely engineering standpoint. I don't believe this is the right approach at all and we have instances to show it is not significantly more rigorous.

 

[Shakespeare 2016]

It feels like to me that the EF scale has been designed and even more markedly implemented to fit the desires of engineers, looking at it from a purely engineering standpoint. I don't believe this is the right approach at all and we have instances to show it is not significantly more rigorous.

Like I have said before on the original F-SCALE Fujita said with an F5 tornado that "INCREDIBLE PHENOMENA WILL OCCUR!" Is there any meaning in that phrase anymore? I have even seen it listed on the EF-SCALE.

 

[Sawmaster]

First post and glad to have found this place where sanity seems to be the norm. I've been 45 years building everything except bank vaults and water towers (and I've seen that happen up close). I can positively tell you there are no buildings made which could satisfy Engineers that they were properly constructed. They live in a dream word of paper and computer screens while we build in a world of time-pressure and conditions which prevent the best of anything. They need to adapt to reality and understand that while some buildings are shoddily built and standard DI's don't apply, they need to be accepting the rest as they are, revising their thinking and application of DI's to reflect that. Won't happen though; just another sadness in life.

Phil