Tornadoes that should have been rated F5/EF5

[Vinny Bell]

The Mayfield tornado probably is a contender in spots, but that is just how the system works. The long track South Central IA EF-4 on Saturday imo was not even close to being EF-5. None of the damage indicators suggest such and NWS Des Moines went with a low end EF-4 rating with winds of 170 mph. Still very devastating. Even if the garage was swept clean away from its foundation, NWS officials look at surrounding damage as well to make sure it lines up with that caliber of damage/wind speed. In this case, the house probably wasn't totally destroyed, and a garage alone is not sufficient enough evidence to warrant an EF-5 damage point. Someone correct me if I'm wrong, but a garage or attached building alone being flattened, would not warrant such. There are also questions about how it is constructed, anchored etc. Answers that were likely given to NWS officials when rating the tornado that led them to arrive at a EF-4 170 mph rating.

Thanks! I thought that garage was a well-anchored house! Thanks!

 

[Jeff Duda]

This is recent- surprisingly. I believe (and still do) that the Mayfield Tornado should have been rated EF-5. For example, there was immense ground scouring, then there was a well-anchored house that was completely leveled. (There are also many cases as such around Mayfield)

Ground scouring is not a damage indicator in the EF scale.

The maximum degree of damage for single-family homes has a wind speed range of 165 - 220, with 200 being the "best guess." The description of DoD 10 says

Destruction of engineered and/or well constructed residence; slab swept clean

Thus, even the full destruction of a well-constructed house is not a sufficient condition for EF5 level winds.

 

[Drew Terril]

Regarding Mayfield-Bremen, a big factor that Tim Marshall brought up at the Summit back in January was just how awful the quality of construction there was. Having lived in Kentucky previously, and having worked in the construction field before, that was unfortunately what I expected. Mayfield in particular has a ton of older construction that just wasn't as well built. Most of the foundations were CMU foundations, and those simply don't hold up under any real stress.

 

[Caleb Routt]

The Western Ky (Mayfield tornado) was more than likely an EF5 especially in the Princeton- Dawson Springs- Earlington- to Bremen segment of the path. The destruction of the UK Research building definitely strikes me as EF5 type damage. I went to Dawson Springs to see some damage about a week after the tornado. While most of the homes weren’t well built, the contextual damage overwhelmingly supports EF5. Including:

• Complete annihilation/granulation of essentially every structure at the tornado centerline

• Entire trees debarked/denuded. Other vegetation completely stripped

• Severe ground & pavement scouring

• A sub vortex developed in a parking lot as the tornado was moving out of town. It leveled a small car wash and moved a few parking stops a couple of inches.

• Well built storage buildings were reduced to bare slabs with the foundation slightly dislodged.

• Industrial buildings completely leveled.

While the EF-Scale is **NOT** a wind scale, both contextual evidence and radar is more than supportive of EF5 in Dawson Springs. However, I can totally understand EF4 180-185 based on nws PAH’s survey.

 

[Caleb Routt]

I also want to stress that aside from the meteorological standpoint, the damage I saw was beyond words and completely startling to see in person. It’s one thing to see damage in pictures but totally different to see in real life. The “wood smell” & people still wondering where their family was about a week after is something horrific to experience.

 

[C M May]

John - if it wasn't anchored down properly, why would you say it's worthy of a 5?

I think folks need to understand that the final rating is not a great indicator of actual overall strength. There are only a finite number of locations where an EF5 rated tornado can be rated EF5 because of the standards necessary to get the rating. It doesn’t mean that a tornado didn’t have EF5 winds or the ability to inflict EF5 damage.

 

[rdale]

I think folks need to understand that the final rating is not a great indicator of actual overall strength.

Compared to the alternative - I think it's the best we have.

 

[C M May]

I'm curious as to what the purpose of this thread is. The aim of the science of using the (enhanced) Fujita scale to rate tornadoes is to estimate the wind speeds in the tornado by sampling damage produced by the tornado. The obvious issues with the EF scale include 1) there need to be sufficiently strong DIs as to bound the damage produced by the tornado, and 2) the tornado must actually impact DIs. Barring the few recent tornadoes in which mobile Doppler radar measurements indicated EF5+ winds within the tornado, why do you think there exists a list of "should be" EF5s? Are you saying you think NWS personnel who rate tornadoes intentionally reduce the final released EF-scale rating? I know there has been some controversy lately with the policy of incorporating mobile radar observations into EF-scale ratings, but to my knowledge, the database of tornado ratings has been rather consistent over time. Keep in mind that the official measurement for observed wind speeds in tornadoes is the maximum 3-second gust at 10 m AGL. While no one would reasonably argue against the fact that there were winds well in excess of 200 mph in the 31 May 2013 El Reno tornado, those measurements were not taken at 10 m AGL; rather they were obtained higher up. So really, the EF3 rating that tornado received is really the best anyone can do with the current state of the science.

Perhaps instead of referring to these tornadoes as "should have been EF5s" we could call them tornadoes that likely had EF5 wind speeds near the surface.

Honestly, to answer your question of “do I think NWS intentionally reduces the final EF scale ratings?” Well? I’m starting to wonder after seeing an interview with Dr Long Pham. I’m sure you’ve seen it. He mentions the dangers of overclassification in regards to willingness of builders and construction engineers to try and build “tornado proof” homes and buildings. Goes as far to insinuate that on high end events the surveys lean as conservative as possible.
I know I know….I’m the grand scheme of things, a rating means nothing to those who have lost loved ones and property. But, if the NWS is going to raise the EF5 threshold to the level of a Jarrell type event, then just come out and say it.