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Enhanced Fujita Ratings Debate Thread (2 Viewers)

Equus

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Saragossa, AL
Saw some more of that minimum possible on display after 3/17 with Moundville, Chilton, and the long track MS one pegged as high as possible without going to the next category; not sure what the aversion to upgrades is but it's certainly a much more conservative application than we had several years ago
 
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75
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Augusta, Kansas
Scouring and debarking/denuding are (at least partially) functions of debris loading. Outside of crop fields and such, you'll notice that most severe vegetation damage tends to occur in proximity to or downstream from significant debris sources. It wouldn't necessarily be surprising to see a strong or violent tornado in an open area not produce the kind of high-end vegetation damage we might otherwise expect. You'd normally see uprooted (and occasionally lofted) trees at least, but even that isn't 100% guaranteed.

Vehicle damage is kinda weird, too. For instance, this study found that significant lofting/rolling of vehicles should be common at EF4+ intensity, yet field observations show only about 15% of vehicles in the paths of such tornadoes are actually flipped or thrown. In fact, around 36% of vehicles didn't move at all. Conversely, even EF1-EF2 tornadoes can very occasionally (~4% of the time) roll or loft vehicles.

In both cases, there are probably a ton of factors at work. The structure of a tornado is incredibly complex and ever-changing, so things like vertical velocity, gust factor, pressure forces, etc. can vary enormously even over incredibly short distances and timespans.

Also, re: winds in violent tornadoes being underestimated, there are a bunch of papers out there on different approaches to simulating tornadoes. It's a fascinating subject, and several of the simulations have exceeded anything we've actually observed. For instance, depending on the swirl ratio, some of the tornadoes in this simulation produced absolutely insane velocities. In one instance, both horizontal and vertical max gusts exceeded 400 mph.

Of course, it's important to remember these are idealized simulations and they don't take into account debris loading and other important factors. They almost certainly don't reflect anything you'd actually see in reality. Still, I think it lends some credence to the idea that we may be underestimating the maximum intensity of the most violent tornadoes.
I highly agree with you.
 
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Augusta, Kansas
Here's another one for you guys. This was probably one of the strongest January tornadoes ever recorded, striking and ripping a slash of death directly through the city of Warren, Arkansas on January 3, 1949, killing 55 people. Eyewitnesses described a multiple-vortex structure as the town was leveled. The tornado had a very long track that was documented from the air.

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This is really violent tornado damage of at least high-end F4 damage. It is even possible this tornado did F5 damage or reached that intensity. I like the way you guys are mentioning all the variables that may cause violent tornado damage. Like I have said before I have wondered what the velocities were on the Sherman, Texas tornado of 1896. It was quite narrow and produced some of the most extraordinary damage ever documented.
 
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Missouri
This is really violent tornado damage of at least high-end F4 damage. It is even possible this tornado did F5 damage or reached that intensity. I like the way you guys are mentioning all the variables that may cause violent tornado damage. Like I have said before I have wondered what the velocities were on the Sherman, Texas tornado of 1896. It was quite narrow and produced some of the most extraordinary damage ever documented.
Sherman reminds me a bit of Pampa, TX of 1995; a "drillbit" type, real narrow but EXTREMELY intense damage. The thing about these tornadoes is that they pretty much have to hit something dead on to do any damage but when they do it's more or less total annihilation.
 
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Augusta, Kansas
Sherman reminds me a bit of Pampa, TX of 1995; a "drillbit" type, real narrow but EXTREMELY intense damage. The thing about these tornadoes is that they pretty much have to hit something dead on to do any damage but when they do it's more or less total annihilation.
I usually watch a bunch of EAS scenarios of tornadoes on YouTube and of course they are hypothetical. It is usually like what if a 3 mile-wide EF5 tornado with winds around 350 mph hit say a city like Chicago dead on? I tend to also ask what if you had a small drill bit EF5 tornado (50-100 yards wide)with inner winds of 375 mph and outer winds of 325 mph hit a major metropolitan dead on? Of course I think the much larger tornado would cause more damage and casualties but of course the small drill bit would still not be any less pleasant than even the huge wedge tornado.
 
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806
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Missouri
I usually watch a bunch of EAS scenarios of tornadoes on YouTube and of course they are hypothetical. It is usually like what if a 3 mile-wide EF5 tornado with winds around 350 mph hit say a city like Chicago dead on? I tend to also ask what if you had a small drill bit EF5 tornado (50-100 yards wide)with inner winds of 375 mph and outer winds of 325 mph hit a major metropolitan dead on? Of course I think the much larger tornado would cause more damage and casualties but of course the small drill bit would still not be any less pleasant than ever the huge wedge tornado.
Well with a wedge the narrow suction vortices and core would do most of the damage, not the main outer circulation. So damage would probably be wildly selective but overall perhaps a bit more (financially at least). In terms of death toll it would depend if it went through the downtown area, suburbs, followed a freeway corridor, etc. So many variables to think about.
 
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75
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Augusta, Kansas
Well with a wedge the narrow suction vortices and core would do most of the damage, not the main outer circulation. So damage would probably be wildly selective but overall perhaps a bit more (financially at least). In terms of death toll it would depend if it went through the downtown area, suburbs, followed a freeway corridor, etc. So many variables to think about.
I agree. To think what 2 tornadoes like the ones I described hitting a major metropolitan area dead on. Both of them being long lived and long tracked. The debris ball signature and radar presentation would be absolutely terrifying.
 
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806
Location
Missouri
I agree. To think what 2 tornadoes like the ones I described hitting a major metropolitan area dead on. Both of them being long lived and long tracked. The debris ball signature and radar presentation would be absolutely terrifying.
I wonder what the Tri-State tornado's debris ball and radar signature would have looked like. It'd probably be unprecedented (at least the debris ball would be).
 

Tennie

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Tennessee
So recently this study was published regarding tornado wind speeds (it's open access, thankfully):


Basically, the Doppler on Wheels (DOW) vehicles measured fairly low-level wind speeds inside a number of tornadoes over the years, and the measured speeds (and corresponding EF-scale ratings) were compared to official NWS damage ratings of the same tornadoes. What was found was that the damage ratings seem to be about 1-2 categories lower (on average) than the radar-measured winds would indicate, suggesting that it usually requires stronger winds to cause at least particular degrees of damage than was previously believed. This and (perhaps) other future studies should at the very least be given some consideration in the future regarding damage ratings.
 

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