Enhanced Fujita Ratings Debate Thread

Kds86z said:

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*keeps mouth shut to avoid sparking off a repeat of earlier events*

On an unrelated note, it's kinda crazy how widely accepted the Birmingham 1998 F5 rating is. Judging by everything I have seen, F4 is more appropriate for that one.

Aaron Rider said:

Next year will mark 30 years since Wisconsin last had a definitely violent tornado! Out of conventionally tornado-prone states, I believe only Michigan has a longer streak. (Massachusetts and New York have more recent ones although both were probably wrongly rated EF3)

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The New York one, if indeed it is the one I'm thinking of (Smithfield 2014), was not rated EF3 but rather EF2. This entailed going below LB for the DI where the most extensive damage occurred.

Do y'all think the April 27, 2011 Cordova EF4 ever reached EF5 intensity? None of the damage indicates an EF5 tornado, but iirc the same supercell produced at least one EF5 tornado and the long track makes me believe there's a chance it was over 200 mph at some location.

Central Ohio Wx said:

Do y'all think the April 27, 2011 Cordova EF4 ever reached EF5 intensity? None of the damage indicates an EF5 tornado, but iirc the same supercell produced at least one EF5 tornado and the long track makes me believe there's a chance it was over 200 mph at some location.

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I think there's a good chance it did over rural areas of northeastern Pickens County to where it hugged the Tuscaloosa/Fayette County line and into southwestern Walker County, but there was nothing there to indicate it. However the radar signatures (reflectivity and velocity) were absolutely insane, even more impressive than Tuscaloosa. James Spann and Jason Simpson were practically incredulous over the numbers their weather computer's algorithm was spitting out based off it.

Central Ohio Wx said:

Do y'all think the April 27, 2011 Cordova EF4 ever reached EF5 intensity? None of the damage indicates an EF5 tornado, but iirc the same supercell produced at least one EF5 tornado and the long track makes me believe there's a chance it was over 200 mph at some location.

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I absolutely believe that Cordova reached EF5 intensity, just didn’t deserve the rating based on pretty much any interpretation of the EF scale.

Given the context of the super outbreak parameters that day, it’s really hard for me to believe that a tornado that was on the ground for 127 miles continuously, being violent for a significant portion of it, and didn’t reach EF5 intensity at any point in its life. Especially when the computers spit out a 17.5 STP value for the supercell while it was producing the Cordova tornado. Also, like you mentioned, the supercell produced 2 EF5s and 2 EF4s by itself throughout its life. Absolutely ludicrous.

On 4/27/11, I wouldn’t be surprised in the slightest if over 10 tornadoes reached EF5 intensity at at least one point in their lives. The slam-dunks are the ones that were either rated EF5 or were controversial EF4s (Tuscaloosa, Ringgold, Flat Rock) and the ones that could have reached EF5 were ones like Cordova or the Tennessee HE EF4.

Central Ohio Wx said:

Do y'all think the April 27, 2011 Cordova EF4 ever reached EF5 intensity? None of the damage indicates an EF5 tornado, but iirc the same supercell produced at least one EF5 tornado and the long track makes me believe there's a chance it was over 200 mph at some location.

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100%.

A lot of the attention from that day goes to the Tuscaloosa supercell and rightfully so, but the Cordova supercell was the supercell of the day in my opinion. The incipient stage of the cell actually merged with the ongoing supercell that had already dropped the Philadelphia, MS EF5 before it crossed the Alabama line. Then shortly after crossing into Alabama it dropped the aforementioned Cordova EF4. Then throughout its life it would drop the Rainsville EF5, the Ringgold EF4, an EF3 in northeastern Tennessee, and finally a few weaker tornados in southwestern Virginia. I’m sure it also dropped some weaker tornados in the rural, mountainous areas of eastern Tennessee.

Now, in the confines of the scale, there is nothing controversial over the Cordova rating. However, as @CheeselandSkies and @slenker mentioned, the environment it was operating in was legitimately as maxed out as you’ll see. As Spann and Simpson watched the storm, it went from an area of a 15.3 STP to an area of 17.5! Which was legitimately mind blowing to both of them. Keep in mind, it’s one thing to see models spit out those values in la la land 3 days before an event, or to see it in a completely capped off plains environment. It’s another to see it actually observed with a fully mature, discrete supercell operating within it. So I completely believe at multiple times in its lifecycle it hit 200+.

Here is a graphic of the evolution of each supercell in NWS Jackson’s area that they posted on their site from that day. Due to the extreme parameter space, look at just how fast the newly born Cordova cell merged with the Philadelphia cell and proceeded to drop a tornado. In the span of ten minutes, merger and all, it developed a perfect shape and dropped a 115+ mile tornado.

ColdFront said:

100%.

A lot of the attention from that day goes to the Tuscaloosa supercell and rightfully so, but the Cordova supercell was the supercell of the day in my opinion. The incipient stage of the cell actually merged with the ongoing supercell that had already dropped the Philadelphia, MS EF5 before it crossed the Alabama line. Then shortly after crossing into Alabama it dropped the aforementioned Cordova EF4. Then throughout its life it would drop the Rainsville EF5, the Ringgold EF4, an EF3 in northeastern Tennessee, and finally a few weaker tornados in southwestern Virginia. I’m sure it also dropped some weaker tornados in the rural, mountainous areas of eastern Tennessee.

Now, in the confines of the scale, there is nothing controversial over the Cordova rating. However, as @CheeselandSkies and @slenker mentioned, the environment it was operating in was legitimately as maxed out as you’ll see. As Spann and Simpson watched the storm, it went from an area of a 15.3 STP to an area of 17.5! Which was legitimately mind blowing to both of them. Keep in mind, it’s one thing to see models spit out those values in la la land 3 days before an event, or to see it in a completely capped off plains environment. It’s another to see it actually observed with a fully mature, discrete supercell operating within it. So I completely believe at multiple times in its lifecycle it hit 200+.

Here is a graphic of the evolution of each supercell in NWS Jackson’s area that they posted on their site from that day. Due to the extreme parameter space, look at just how fast the newly born Cordova cell merged with the Philadelphia cell and proceeded to drop a tornado. In the span of ten minutes, merger and all, it developed a perfect shape and dropped a 115+ mile tornado.

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I'm not sure if those values represented the STP or "significant tornado parameter" as we think of it in the forecasting/parameter space diagnostic tool sense. The term they used was "significant tornado index" which I took to mean some sort of algorithm used by their weather software (not sure what they were using at the time, my station uses The Weather Company's MAX Studio) to assess the storm based off the radar signature (in addition to the "significant tornado index," it also spits out a "tornado impact" number, no idea what the difference is between the two or how they relate to each other).

In any case, numbers like that mean, essentially, "s*** is hitting the fan."

CheeselandSkies said:

I'm not sure if those values represented the STP or "significant tornado parameter" as we think of it in the forecasting/parameter space diagnostic tool sense. The term they used was "significant tornado index" which I took to mean some sort of algorithm used by their weather software (not sure what they were using at the time, my station uses The Weather Company's MAX Studio) to assess the storm based off the radar signature (in addition to the "significant tornado index," it also spits out a "tornado impact" number, no idea what the difference is between the two or how they relate to each other).

In any case, numbers like that mean, essentially, "s*** is hitting the fan."

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I’m pretty sure I read on here a post from Fred where he was stating that specific index, the significant tornado index, was basically just what their software was calling STP. I’ll see if I can find it. However, I’ve personally seen some RAP reanalysis soundings from the Cordova area that day, and the STP was reaching up and a little over 17.


I’m having trouble quoting on mobile, but here is the post:

An interesting tidbit about that Significant Tornado Index in their radar software from back then... We didn't realize it at the time, but instead of that being WSI's equivalent of the Baron Tornado Index and just a 1-10 ranking, that was just their point-readout of the STP and WSI used the word "Index" instead of "Parameter". It was just a readout of mesoscale analysis data at the location of the SCIT in the radar data, similar to the CAPE, SRH, etc., that was also listed in those marquee boxes when they came up. This explains why the "Significant Tornado Index" was as high as 15-17.5 later in the coverage... because mesoanalysis STP values ended up running that high in west central Alabama that afternoon. The "Tornado Impact" number is their answer to the Baron Tornado Index (BTI) and does run 0-10 or 1-10 like the BTI does.

Post in thread 'Discussion of April 27, 2011 Outbreak'
https://talkweather.com/threads/discussion-of-april-27-2011-outbreak.421/post-74530

Central Ohio Wx said:

Do y'all think the April 27, 2011 Cordova EF4 ever reached EF5 intensity? None of the damage indicates an EF5 tornado, but iirc the same supercell produced at least one EF5 tornado and the long track makes me believe there's a chance it was over 200 mph at some location.

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Actually, @TH2002 found an (unsurveyed) plausibly well-built house in Cullman County which he considered EF5 damage. He mentioned it in a post a while back:

TH2002 said:

Cordova: a newly built, plausibly well constructed home was swept away in Cullman County that was missed in the survey. That, plus the contextual damage is enough for EF5 imo.

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Lake Martin EF4 said:

Actually, @TH2002 found an (unsurveyed) plausibly well-built house in Cullman County which he considered EF5 damage. He mentioned it in a post a while back:

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Yup. This home specifically:


This photo speaks for itself. I believe it was also taken in Cullman County, but not 100% sure:

TH2002 said:

Yup. This home specifically:
-pic

This photo speaks for itself. I believe it was also taken in Cullman County, but not 100% sure:
-pic

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The first image is the first damage photo I’ve seen of Cordova that shows a slab. Every other image I’ve seen is the two images of the patchy Philadelphia-like scouring (which to me really didn’t seem overly impressive) and of the crater left behind by a semi impacting the ground (which is still an extremely impressive image to me by itself) (also I could be mixing this up with another tornado)

I’m really astounded at how violent that bottom image is - any time I see that 1-2 punch of prominent and very clear grass scouring coinciding with tree damage of that caliber, I don’t think it is that unreasonable to automatically assume EF5 intensity there.

More of Tony Lyza tearing apart recent interpretations of the EF-scale, as it is skewing frequencies of not only F/EF5 tornadoes, but 3s and 4s too. It is fundamentally altering the climatology and its associated risk profile in terms of fatalities/etc.

Overall, these results indicate that not only are current tornado rating practices inconsistent with
the 30-year F-Scale climatology, but they are also inconsistent with any past tornado rating
period, including the early years of the EF-Scale era from 2007–2013.

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andyhb said:

On the Consistency between the Fujita and Enhanced Fujita Scales and Implications for the United States Tornado Climatology

Abstract The Fujita (F) and Enhanced Fujita (EF) Scales have formed the baseline for tornado-intensity estimation in the United States tornado climatology. Ahead of the EF-Scale’s debut in 2007, one stated goal was to maintain consistency in the ratings between the two scales (i.e., a rating...

journals.ametsoc.org

More of Tony Lyza tearing apart recent interpretations of the EF-scale, as it is skewing frequencies of not only F/EF5 tornadoes, but 3s and 4s too. It is fundamentally altering the climatology and its associated risk profile in terms of fatalities/etc.

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This really caught my eye as well:

Subsequently, the rate of fatalities associated with a given EF3 or EF4 tornado in the 2014–2023 are substantially greater than for F3 or F4 tornadoes in the 30-year climatology, with the average EF4 tornado from 2014–2023 being over 2.5 times deadlier than the average F4 tornado from 1977–2006.

ColdFront said:

This really caught my eye as well:

Subsequently, the rate of fatalities associated with a given EF3 or EF4 tornado in the 2014–2023 are substantially greater than for F3 or F4 tornadoes in the 30-year climatology, with the average EF4 tornado from 2014–2023 being over 2.5 times deadlier than the average F4 tornado from 1977–2006.

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My first thought is that higher ratings recently are being increasingly restricted to populated areas (i.e. more exposure of people) given the interpretations of the EF-scale.

andyhb said:

On the Consistency between the Fujita and Enhanced Fujita Scales and Implications for the United States Tornado Climatology

Abstract The Fujita (F) and Enhanced Fujita (EF) Scales have formed the baseline for tornado-intensity estimation in the United States tornado climatology. Ahead of the EF-Scale’s debut in 2007, one stated goal was to maintain consistency in the ratings between the two scales (i.e., a rating...

journals.ametsoc.org

More of Tony Lyza tearing apart recent interpretations of the EF-scale, as it is skewing frequencies of not only F/EF5 tornadoes, but 3s and 4s too. It is fundamentally altering the climatology and its associated risk profile in terms of fatalities/etc.

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its Restricted access, cant really look at it.

andyhb said:

My first thought is that higher ratings recently are being increasingly restricted to populated areas (i.e. more exposure of people) given the interpretations of the EF-scale.

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Same.

My other thought, and it’s probably a very simplistic take on the current scale, is that 4s are the new 5s and 3s are the new 4s.

TH2002 said:

Yup. This home specifically:

This photo speaks for itself. I believe it was also taken in Cullman County, but not 100% sure:

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The contextual damage certainly looks really violent, at least(HE EF4). The house was sure swept away in an unusual fashion as some of the debris certainly looks rather large than what you would see with an EF5. Maybe others on here are seeing something that I am not.

Lake Martin EF4 said:

Screw it here's a list of tornadoes (that I know of) that would likely get EF5 if they happened today:

1925 Tri-State
1953 Flint
1956 Hudsonville
1957 Fargo (?)
1965 Coldwater Lake #1
1965 Sunnyside
1965 Pittsfield-Strongsville
1970 Lubbock
1974 Brandenburg
1974 Tanner #1
1974 Guin
1977 Smithfield
1985 Niles-Wheatland
1990 Hesston
1990 Goessel
1991 Andover
1992 Chandler (?)
1996 Oakfield (?)
1997 Jarrell
1998 Waynesboro (?)
1999 Bridge Creek
2004 Marion (?)
2007 Greensburg
2008 Parkersburg
2011 Philadelphia (?)
2011 Hackleburg
2011 Smithville
2011 Tuscaloosa (?)
2011 Rainsville (?)
2011 Ringgold
2011 Joplin
2011 Piedmont
2011 Chickasha
2011 Goldsby
2013 Moore
2014 Vilonia
2014 Louisville (?)

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Somewhat older post I understand, but do you happen to have any photos from the 1st Tanner F5 that make you put it on this list? I can't find "much" from it that is super high end, at least to put it with the higher end 4/3 F5s like it is here, I honestly think the 2nd Tanner F5 may be stronger, or at least considerably underrated, out of any F5s from that day, I'd say it could/is stronger than a few - images below, the worst highlighted





Here is the Facebook post most of these werte sourced from, some of the images in the post have been shared here before but a good amount have not, very little imagery from this area I'm imagining, I don't see Hazel Green thrown around a lot -

ColdFront said:

Same.

My other thought, and it’s probably a very simplistic take on the current scale, is that 4s are the new 5s and 3s are the new 4s.

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I'd thought some time ago that for very old reports you need to mentally subtract about a 'half', and for some modern ones add a 'half'. In particular, I think a good number of recent high end EF3s would have been rated F4 with little (perhaps too little) thought up until 2002.

Damage from the Trenton EF4. I have no doubt in my mind this tornado reached EF5 intensity (kinda like Cordova) at some point along its path, although the damage doesn't really suggest that. Was close in prosimity to the Fackler EF4, Rainsville EF5, Ringgold EF4, and was produced by the Cullman EF4 supercell.