Enhanced Fujita Ratings Debate Thread

[SouthFLwx]

Unrelated to the current discussion, but I recently came across this photo from the 2024 Minden tornado and it made me go "hmmm..."

I initially agreed with the EF3 rating, but I have to say this particular home is definitely a head scratcher. It appears to be a large and well-constructed home swept completely away, and this photo was taken the day after the tornado, so no cleanup here. Unless there were major construction flaws not visible here, the adequate anchoring + the partial debarking in the background seems like enough support for at least low-end EF4. Plus, the 224 MPH DOW measurement is (IMO) further credence that the original F scale's wind speed estimates were more accurate than the EF scale.

And to alleviate any confusion, the home above is a completely different structure from this one. For the second one, I actually agree with EF3 as it was much smaller than the home above and was obliterated in a sub-violent fashion despite the anchoring.

I have always thought that Minden deserved low-end EF4. The fact that a few homes were swept away + the intense contextual damage is enough for ~170 mph imo.

 

[buckeye05]

I have always thought that Minden deserved low-end EF4. The fact that a few homes were swept away + the intense contextual damage is enough for ~170 mph imo.

Thought the same until I took a closer look. Immediately adjacent houses were left intact, and the ones that were removed from their foundations slid off and crumbled in a heap slider style, despite the anchoring. In fact, one of the empty foundations in the photos you posted were from a house that wasn’t even leveled; it was pushed off and remained largely intact. Also contextual damage wasn’t anything a high-end EF3 couldn’t produce. EF3 is fine if we’re strictly speaking damage wise, despite the fact that this tornado contained sub-vortices that were well into the violent range.

 

[TH2002]

Thought the same until I took a closer look. Neighboring houses were left intact, and the ones that were removed from their foundations slid off and crumbled slider style, despite the anchoring. The contextual damage wasn’t anything a high-end EF3 couldn’t produce. EF3 is fine.

What about the larger home in the first photo I posted? Do you have additional images to show that one also failed slider style?

For the second, smaller one, I do definitely agree with EF3 though.

 

[buckeye05]

What about the larger home in the first photo I posted? Do you have additional images to show that one also failed slider style?

For the second, smaller one, I do definitely agree with EF3 though.

I remember figuring it out after looking at images posted on the forum thread from this outbreak. There were some aerial photos that negated a solid EF4 rating. I didn’t save them unfortunately.

Edit: I believe there was some evidence of collateral damage as well (houses smashing into one another)

 

[Grand Poo Bah]

Minden definitely looked like it had violent motion as it clipped the edge of town too. Watch on mute if you want to keep your brain cells intact. He had some big Youtuber riding along who was being beyond obnoxious.

 

[Grand Poo Bah]

Plus, the 224 MPH DOW measurement is (IMO) further credence that the original F scale's wind speed estimates were more accurate than the EF scale.

Never made a huge fuss about Minden because those two buildings probably weren't enough to conclusively prove violent winds, especially because the rest of the town only sustained EF2-EF3 damage. Even during the best times of the F scale it may have still only gotten an F3 rating based on the amount of uncertainty. However, I wholeheartedly agree with this bolded statement. These were likely the only two structures close enough to the core to take a glancing blow, and the DOW scan aligns perfectly with a low end F4 rating.



During the F scale era Jordan Hall's video might've been used as evidence that the town didn't take a direct hit, and the core was much more powerful, which could've been used to justify an upgraded rating. This paired with the DOW scan makes an F4 rating much more logical. And who isn't a fan of logical thinking?

 

[Western_KS_Wx]

Greensburg produced some extraordinary contextual damage and the damage to the school speaks for itself. It was in no world a “ marginal “ EF5.

I’ve said this a couple of times before, but the scarce documentation of the tornado’s most extreme damage and the incredibly complex damage swath is where this misconception of it being “marginal” came from. The reason ‘only’ 8 structures (7 residences, School) received an EF5 rating was strictly due to the construction quality in the town not being all that great. That being said, the damage inflicted in some locations is easily up there some of the most extreme damage seen in modern history, and definitely on par with other EF5’s we’ve seen.

 

[Grand Poo Bah]

I’ve said this a couple of times before, but the scarce documentation of the tornado’s most extreme damage and the incredibly complex damage swath is where this misconception of it being “marginal” came from. The reason ‘only’ 8 structures (7 residences, School) received an EF5 rating was strictly due to the construction quality in the town not being all that great. That being said, the damage inflicted in some locations is easily up there some of the most extreme damage seen in modern history, and definitely on par with other EF5’s we’ve seen. View attachment 43684View attachment 43685View attachment 43686View attachment 43687

Wait the school recieved an EF5 rating? I was under the impression houses were the only EF scale DI ever to receive the EF5 rating. Seems more scrutiny would've been good on my part before accepting that info as fact. My bad, y'all.

These photos are incredible. Thanks for sharing. I wonder if part of the bias towards this one is due to the fact a lot of these houses were rated EF2 and EF3. People mistook the lower rated structures as a lack of complete destruction throughout the town, rather than the construction scrutiny the ratings actually represent.

 

[Western_KS_Wx]

Wait the school recieved an EF5 rating? I was under the impression houses were the only EF scale DI ever to receive the EF5 rating. Seems more scrutiny would've been good on my part before accepting that info as fact. My bad, y'all.

These photos are incredible. Thanks for sharing. I wonder if part of the bias towards this one is due to the fact a lot of these houses were rated EF2 and EF3. People mistook the lower rated structures as a lack of complete destruction throughout the town, rather than the construction scrutiny the ratings actually represent.

The QRT team and NWS Dodge City has the school rated as EF5. Tim Marshall assigned a high-end EF4, though agrees it’s some of the most extreme damage to a school or institutional building he’s seen and it could go both ways pretty much.

 

[Grand Poo Bah]

The QRT team and NWS Dodge City has the school rated as EF5. Tim Marshall assigned a high-end EF4, though agrees it’s some of the most extreme damage to a school or institutional building he’s seen and it could go both ways pretty much.

I see! That makes sense. If it's some of the most extreme damage he's ever seen to that building type I wonder why he rated it EF4. Seems contradictory.

It's probably safe to assume the answer to the popular question "which EF5s were low-end?" is "none of them", because every single EF5 is miles above the written F5 and EF5 thresholds "low-end" simply just doesn't apply.

 

[Grand Poo Bah]

I wonder if part of the bias towards this one is due to the fact a lot of these houses were rated EF2 and EF3. People mistook the lower rated structures as a lack of complete destruction throughout the town, rather than the construction scrutiny the ratings actually represent.

looking closer I can see where a few of the big differences between ratings could be located. So it's not entirely the scale's fault. Greensburg would be a great tornado for one of @joshoctober16 's rating/subvortex contours. Looks like it had a strong core with extremely violent sub vortices

 

[Grand Poo Bah]

what i was trying to say is , im wondering if super strong velocity tornadoes could be made by tornadoes that seem to barely have any vertical motion (el reno 2013 had this)

compared to Moore 2013 that had very strong upwards motion when doing its violent damage

I've been giving this some thought, and I think based on the way horizontal winds along the ground tilt into vertical inside the core of the tornado, tornado winds are never purely vertical or horizontal, but more diagonal. The winds on ground level are pounding into the ground on one side, and lofting into the air on the other. Imagine it as a tilted disk at ground level with strong suction in the middle. The most powerful area is where the disk sweeps the surface. The suction becomes stronger as the centrifugal force of the rotation becomes stronger, driving the debris upwards. That's when the real lofting and vertical winds happen. This is what Moore 2013 looked like.



I'm more iffy on this but here's what I imagine a multi vortex wedge without a grounded core to look like. The suction vortices are too short lived to loft much so most of the debris stays on the ground. Anything it can drag into the central core will still get lofted high, but the centrifugal nature of it will throw most debris outward. This explains El Reno 2013. (Source of picture)

 

[zath]

Throwing this out there in case no one has seen them before, but I would recommend watching some of the simulations that Leigh Orf does around vorticity interactions and how they relate to tornado genesis and single-cell vs multi-cell tornadoes, along with pressure drops. They do cover some events like El Reno, Moore, and Mayfield. Example: https://www.youtube.com/watch?v=opF2LeEu7z0 (And of course there is the video by Chris Broyles about the Moore 2013 tornado here. If nothing else, the simulations are mesmerizing to watch haha.

 

[Western_KS_Wx]

looking closer I can see where a few of the big differences between ratings could be located. So it's not entirely the scale's fault. Greensburg would be a great tornado for one of @joshoctober16 's rating/subvortex contours. Looks like it had a strong core with extremely violent sub vortices

View attachment 43775
View attachment 43776

Here’s some more detailed photos of each structural damage indicator. Some of these legitimately don’t make sense lol. Once I complete an EF scale contour map it’ll really make the individual vortices stand out much more obviously.

 

[Grand Poo Bah]

Here’s some more detailed photos of each structural damage indicator. Some of these legitimately don’t make sense lol. Once I complete an EF scale contour map it’ll really make the individual vortices stand out much more obviously.

View attachment 43831View attachment 43832View attachment 43833

Really amazing work here! Holy buckets. Are you going to try stitching it all together into one really high resolution image of the whole town? I could probably assist with that if you need it. it'll be interesting to try and sketch out some cycloidal patterns when this is finished.

 

[Tomcats Forever!]

For whatever reason, LUB just added an EF5 DI to the DAT for the 6/5 Morton tornado. For a raxpol measurement of all of 80 kts. So don't get too excited. Typo probably.

 

[Lake Martin EF4]

For whatever reason, LUB just added an EF5 DI to the DAT for the 6/5 Morton tornado. For a raxpol measurement of all of 80 kts. So don't get too excited. Typo probably.

Lubbock office, too. Take your photos now. It won't be there for long.

 

[Atlantic]

Lubbock office, too. Take your photos now. It won't be there for long.

I thought it was already removed? I swear I just saw something on another thread about it being removed?

 

[pohnpei]

Unrelated to the current discussion, but I recently came across this photo from the 2024 Minden tornado and it made me go "hmmm..."

I initially agreed with the EF3 rating, but I have to say this particular home is definitely a head scratcher. It appears to be a large and well-constructed home swept completely away, and this photo was taken the day after the tornado, so no cleanup here. Unless there were major construction flaws not visible here, the adequate anchoring + the partial debarking in the background seems like enough support for at least low-end EF4. Plus, the 224 MPH DOW measurement is (IMO) further credence that the original F scale's wind speed estimates were more accurate than the EF scale.

And to alleviate any confusion, the home above is a completely different structure from this one. For the second one, I actually agree with EF3 as it was much smaller than the home above and was obliterated in a sub-violent fashion despite the anchoring.

Translating mobile radar-detected wind speeds to damage is not a straightforward matter. I previously wrote an article specifically discussing this issue. It’s not that such discussions are entirely impossible, but each case must be analyzed individually rather than simply comparing the maximum radar velocity to the tornado’s strongest damage.

In the case of the Minden, IA tornado, the 224 mph radar wind speed occurred at 23:08Z. This was a Vg value, adjusted from a Vd of 79 m/s, at a height exceeding 250 meters. At this time, the tornado was not condensed at all, exhibiting a multi-vortex structure and appearing to have just undergone a significant weakening phase. There was no corresponding damage reference point, and this was certainly not a near-ground wind speed. Therefore, the 224 mph value itself cannot be used to indicate anything in this context.

Specifically, I believe that if there had been close-range mobile radar observations around 22:55Z, the tornado would likely have exhibited much stronger wind speeds. As for the EF3 damage in the town of Minden, it occurred around 22:43Z, at which point mobile radar scans had not even begun.
Pics below is the scan of 224mph and what the tornado looked like at this time

 

[buckeye05]

Just FYI, Nick K is now in agreement that Lake City, AR deserves an EF4 rating and is publicly questioning MEGs surveying practices. Regardless of our personal opinions of him, we could have hashed it out in a civilized, articulate manner here and potentially had a new contributor to the forum who has some solid connections and influence, instead of sweeping him away in a tsunami of unadulterated unhinged weenie rage.