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Tornado Outbreak Aftermath: April 26th-30th, 2014


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I don't know if i'm misinterpreting your post, but only one or two (calling Joplin a big city is a stretch) of the 10 official EF5s hit large metro areas. The rest were rural/small towns.

Joplin wasn't a small town either. I really should've said "decent-sized cities", but you get the point. Moore/Joplin would never have received EF5 ratings if they hit Vilonia. But I see your point. I think the difference between Hackleburg/Smithville/Rainsville and Vilonia were that the former were off the charts by quite a bit, whereas the latter was only barely off the charts.

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Of course a slabbed home by itself is not indicative of EF5 damage. It isn't necessarily even EF4 depending on construction quality. And surrounding context absolutely matters, which is what I've been saying. My point is that if you have damage that you can credibly rate EF5 (i.e. the context supports the rating), the tornado is an EF5. Tornadoes have always been rated on the maximum damage caused, even if that damage is only in a very isolated area (which doesn't even apply here). I thought you were saying the opposite, but maybe I misunderstood you.

 

In any event, my original point relates directly to the point that you bolded: the EF-scale is not consistent with the F-scale. Not at all. I suspect if all historical F5s were re-rated by the ultra-conservative current standards, we'd have a lot fewer F5s. Conversely, many of the current high-end EF4s would be no-doubt F5 ratings in the past. It simply isn't consistent at all. Although the surveyors on the ground obviously have much more information than we can possibly glean from photos/video, I think there's enough information (including, most importantly, surrounding context) to say that this tornado would almost certainly have been an F5 on the old scale. I'd tend to think it may have even been rated EF5 today if it had been a different group surveying it. It's just very puzzling.

 

I actually didn't bold that first part, that was from the website itself. But to your point, I think the EF scale has nothing to do with conservative ratings. It's that the science has advanced far enough to understand how structures respond to wind stress. Yes, this gets added back into the EF scale, but it's not like we created this new version to weed out EF5s. The idea was that it didn't take 261 mph to slab a house in reality, more like 200 mph. So a EF5 now would be comparable to an EF5 of old.

 

The main point is tornadoes aren't being rated weaker, we've just learned that it takes weaker winds to do the damage we are seeing. The wind speeds were always (and still are) an estimation, and it happened we did the best we could with the information given back in the day.

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Unless something has changed, the latest official word that I saw was mobile radar data will not be used to rate a tornado, but instead will only be noted in the Storm Data entry as additional info. This despite the fact that the EF-scale paper clearly states remote sensing info should be used if deemed reliable.

 

It won't be a determining thing but it will tip the scale. For instance, I'd say mobile doppler tipped the scale in Piedmont/El Reno 2011. You and I and everyone else knows they wouldn't have rated it EF5 without the radar data. Whatever happened to the cactus rig would have not warranted a posthumous upgrade.

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The ironic part about the Hattiesburg example is that nowhere in the damage survey can I find EF4 damage listed, besides a narrative. All I see is high end EF3 mentioned, even in the KML file of surveyed points.

 

LSX indeed seems to only have one damage indicator listed at EF4, but I'm sure that it was consistent with nearby damage indicators in order to make that call.

 

In a similar vein, wasn't the Woodbury/Cherokee County, IA EF4 on 10/4/13 rated as such solely based on a grain wagon being thrown 400 yards? I don't recall there being EF4 structural damage anywhere. Also the 4/22/11 Good Friday EF4 in St. Louis was rated as such based on a single home that was swept away. There are many other examples as well.

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Joplin wasn't a small town either. I really should've said "decent-sized cities", but you get the point. Moore/Joplin would never have received EF5 ratings if they hit Vilonia. But I see your point. I think the difference between Hackleburg/Smithville/Rainsville and Vilonia were that the former were off the charts by quite a bit, whereas the latter was only barely off the charts.

 

I'm not sure you truly appreciate how strong and rare an EF4 is. The size of the city has nothing to do with the rating. Greensburg has a population under 1,000. Parkersburg under 2,000. Hackleburg had winds estimated at 210 mph, Greensburg 205 mph, Vilonia 190 mph. They were all strong, some just stronger than others.

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I actually didn't bold that first part, that was from the website itself. But to your point, I think the EF scale has nothing to do with conservative ratings. It's that the science has advanced far enough to understand how structures respond to wind stress. Yes, this gets added back into the EF scale, but it's not like we created this new version to weed out EF5s. The idea was that it didn't take 261 mph to slab a house in reality, more like 200 mph. So a EF5 now would be comparable to an EF5 of old.

 

The main point is tornadoes aren't being rated weaker, we've just learned that it takes weaker winds to do the damage we are seeing. The wind speeds were always (and still are) an estimation, and it happened we did the best we could with the information given back in the day.

 

I agree the wind speeds are likely more realistic (at least as far as the EF4/5 threshold -- high-end EF5s are obviously still far above 200 mph), but that's not what I'm talking about. I'm just talking about the damage consistency from scale to scale, irrespective of whatever wind speed estimates we assign to them. Many of the tornadoes that receive "high-end EF4" ratings today would have been no-doubt F5s at many times in the past, while a good number of past F5s may not even be considered high-end EF4s today.

 

That's the objection I have. If we want to apply stricter standards to EF5s, so be it. I'm all for scientific accuracy. But we can't pretend that there's any real consistency.

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In a similar vein, wasn't the Woodbury/Cherokee County, IA EF4 on 10/4/13 rated as such solely based on a grain wagon being thrown 400 yards? I don't recall there being EF4 structural damage anywhere. Also the 4/22/11 Good Friday EF4 in St. Louis was rated as such based on a single home that was swept away. There are many other examples as well.

 

This was the LSX survey I mentioned before. It was only one damage indicator, but if it was embedded within homes of high end EF3 it makes sense.

 

Woodbury actually had two damage indicators of EF4 at the same farmstead. One location is a lot different than just one damage indicator.

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I agree the wind speeds are likely more realistic (at least as far as the EF4/5 threshold -- high-end EF5s are obviously still far above 200 mph), but that's not what I'm talking about. I'm just talking about the damage consistency from scale to scale, irrespective of whatever wind speed estimates we assign to them. Many of the tornadoes that receive "high-end EF4" ratings today would have been no-doubt F5s at many times in the past, while a good number of past F5s may not even be considered high-end EF4s today.

 

That's the objection I have. If we want to apply stricter standards to EF5s, so be it. I'm all for scientific accuracy. But we can't pretend that there's any real consistency.

 

I think by default there can't be any consistency as we improve damage assessments, but it's the best we can do at the moment. Even mobile radars aren't a be all end all. They work great for Oklahoma, but what about a tornado in New York what are the chances they can benefit from the same wealth of data? I'm all for using all available data sources, but that will introduce further inconsistency too.

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In a similar vein, wasn't the Woodbury/Cherokee County, IA EF4 on 10/4/13 rated as such solely based on a grain wagon being thrown 400 yards? I don't recall there being EF4 structural damage anywhere. Also the 4/22/11 Good Friday EF4 in St. Louis was rated as such based on a single home that was swept away. There are many other examples as well.

Actually to build on that point, the Philadelphia, Rainsville, Joplin, and 2011 El Reno tornadoes didn't sweep away any homes well-built enough to warrant EF5 by themselves. The EF5 rating in those cases was based specific incidences of incredible damage using non-traditional DIs. The 2011 El Reno rating was mostly based on a toppled oil rig,  and Philadelphia was based on very deep ground scouring. Rainsville and Joplin were based on a slew of very specific non-structural things such as concrete porches being ripped away, a safe being ripped from it's bolts, ground and pavement scouring, concrete footings pulled up, vehicles tossed remarkable distances, and removal of parking stops and manhole covers.

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I can't believe we're seeing NWS offices applying inconsistent standards to determine how much/how many instances of an X intensity damage is needed for a tornado to be classified at Y intensity. A history of past F5s shows how inconsistent the rating decision is in the case of Vilonia. The 1966 Belmond, IA, tornado was rated F5 based on only on one home, and in far more dubious circumstances (a debris pile next to the foundation, with no scouring and only minimal damage to nearby homes) than in this case, where reasonably well built/well built homes were completely swept away, ground scouring was visible (near the foundation), intense wind rowing occurred (again near the foundation), etc. Valley Mills 1973 was rated F5 because it threw two vehicles hundreds of yards, but only produced F2 building damage. Broken Bow 1982 was rated F5 based on damage to one home. Plainfield 1991 was rated F5 based on ONE patch of extreme ground scouring. Many tornadoes have been rated F3, F4, etc. based on damage at one point, so why not apply the same standard to F5 candidates? If one home was well built, especially if surrounding indicators pointed to F5, then the tornado was an F5/EF5, period.

 

Sadly, this is not the first time Little Rock has been conservative with its ratings. The Clinton tornado from Super Tuesday 2008 was in my view clearly an EF5, having left large foundations bare, trailer chassis twisted into unrecognizable shapes, two-foot-thick trees debarked and snapped off near ground level, destroyed a (steel-reinforced?) boat factory to the ground, produced ground scouring…and was rated EF4. Radar and aerial footage showed EF5 indicators that were ignored because AR just doesn't "get" F5s.

 

Anyway, so long as the NWS remains so inconsistent in its rationale for ratings (as the recent fiasco over radar measurements illustrates), then I'm no longer going to rely on the already-inaccurate NCDC/SPC database for tornado climatology. I'll just use Grazulis or my own estimates. *Rant over*

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Actually to build on that point, the Philadelphia, Rainsville, Joplin, and 2011 El Reno tornadoes didn't sweep away any homes well-built enough to warrant EF5 by themselves. The EF5 rating in those cases was based specific incidences of incredible damage using non-traditional DIs. The 2011 El Reno rating was mostly based on a toppled oil rig,  and Philadelphia was based on very deep ground scouring. Rainsville and Joplin were based on a slew of very specific non-structural things such as concrete porches being ripped away, a safe being ripped from it's bolts, ground and pavement scouring, concrete footings pulled up, vehicles tossed remarkable distances, and removal of parking stops and manhole covers.

 

That's correct when it comes to Joplin. I don't believe there were any structures in the path built to survive an EF-5 and most of the structures in the path would have been damaged or destroyed with an EF-2/3. Construction plays a big part. There were homes that were 'swept away' but they were poorly constructed and the nearby homes didn't sustain the same level of damage. 

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Some good points here.  And let's face it, F5s/EF5s are sacred...they make up such a small fraction of the data set.  They live on forever.  For anyone who has any knowledge about severe weather history, all you have to do is name a town and know what it pertains to.  If you're surveying, you should want to be as comfortable as possible with whatever rating you assign and that's probably especially the case when deciding between EF4/EF5.  It'll be interesting to read the full survey whenever it comes out.      

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I can't believe we're seeing NWS offices applying inconsistent standards to determine how much/how many instances of an X intensity damage is needed for a tornado to be classified at Y intensity. A history of past F5s shows how inconsistent the rating decision is in the case of Vilonia. The 1966 Belmond, IA, tornado was rated F5 based on only on one home, and in far more dubious circumstances (a debris pile next to the foundation, with no scouring and only minimal damage to nearby homes) than in this case, where reasonably well built/well built homes were completely swept away, ground scouring was visible (near the foundation), intense wind rowing occurred (again near the foundation), etc. Valley Mills 1973 was rated F5 because it threw two vehicles hundreds of yards, but only produced F2 building damage. Broken Bow 1982 was rated F5 based on damage to one home. Plainfield 1991 was rated F5 based on ONE patch of extreme ground scouring. Many tornadoes have been rated F3, F4, etc. based on damage at one point, so why not apply the same standard to F5 candidates? If one home was well built, especially if surrounding indicators pointed to F5, then the tornado was an F5/EF5, period.

 

Sadly, this is not the first time Little Rock has been conservative with its ratings. The Clinton tornado from Super Tuesday 2008 was in my view clearly an EF5, having left large foundations bare, trailer chassis twisted into unrecognizable shapes, two-foot-thick trees debarked and snapped off near ground level, destroyed a (steel-reinforced?) boat factory to the ground, produced ground scouring…and was rated EF4. Radar and aerial footage showed EF5 indicators that were ignored because AR just doesn't "get" F5s.

 

Anyway, so long as the NWS remains so inconsistent in its rationale for ratings (as the recent fiasco over radar measurements illustrates), then I'm no longer going to rely on the already-inaccurate NCDC/SPC database for tornado climatology. I'll just use Grazulis or my own estimates. *Rant over*

 

This isn't a conspiracy. A couple still photos and a YouTube video of an aerial survey isn't enough information to base a tornado rating on. As JoMo points out, if homes weren't built to withstand EF4 damage there is no way to know whether it was truly an EF5 without other evidence. Sucks but that's the way it is.

 

And I think it's been fairly well established that prior practices of rating F5s weren't iron clad (see La Plata).

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Is ground scouring thought to be from the funnel itself or the debris contained therein?

Some of the debris profiles of different tornadoes may also cause more intense debris fields because of the type of debris a tornado interacts with.

160 mph winds in Oklahoma won't do as much damage as in the Southeast, namely because there is far less physical matter with weight and mass to contribute to the destruction.

When a tornado hits the South in early Spring, you've got moist soil and an abundance of pine tree missiles to fill out the debris profile of a tornado. Bad scenario.

There's a good study about this I read where they investigated this hypothesis showing some more intense damage potential with varying soil compositions/moistures.

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Actually to build on that point, the Philadelphia, Rainsville, Joplin, and 2011 El Reno tornadoes didn't sweep away any homes well-built enough to warrant EF5 by themselves. The EF5 rating in those cases was based specific incidences of incredible damage using non-traditional DIs. The 2011 El Reno rating was mostly based on a toppled oil rig,  and Philadelphia was based on very deep ground scouring. Rainsville and Joplin were based on a slew of very specific non-structural things such as concrete porches being ripped away, a safe being ripped from it's bolts, ground and pavement scouring, concrete footings pulled up, vehicles tossed remarkable distances, and removal of parking stops and manhole covers.

 

 

That gets into office to office differences on whether to factor in non-traditional indicators.  2012 Henryville ripped up large chunks of concrete/boulders and tossed it some distance but Louisville didn't seem to factor it in or at least wasn't overly impressed.  

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I can't believe we're seeing NWS offices applying inconsistent standards to determine how much/how many instances of an X intensity damage is needed for a tornado to be classified at Y intensity. A history of past F5s shows how inconsistent the rating decision is in the case of Vilonia. The 1966 Belmond, IA, tornado was rated F5 based on only on one home, and in far more dubious circumstances (a debris pile next to the foundation, with no scouring and only minimal damage to nearby homes) than in this case, where reasonably well built/well built homes were completely swept away, ground scouring was visible (near the foundation), intense wind rowing occurred (again near the foundation), etc. Valley Mills 1973 was rated F5 because it threw two vehicles hundreds of yards, but only produced F2 building damage. Broken Bow 1982 was rated F5 based on damage to one home. Plainfield 1991 was rated F5 based on ONE patch of extreme ground scouring. Many tornadoes have been rated F3, F4, etc. based on damage at one point, so why not apply the same standard to F5 candidates? If one home was well built, especially if surrounding indicators pointed to F5, then the tornado was an F5/EF5, period.

 

Sadly, this is not the first time Little Rock has been conservative with its ratings. The Clinton tornado from Super Tuesday 2008 was in my view clearly an EF5, having left large foundations bare, trailer chassis twisted into unrecognizable shapes, two-foot-thick trees debarked and snapped off near ground level, destroyed a (steel-reinforced?) boat factory to the ground, produced ground scouring…and was rated EF4. Radar and aerial footage showed EF5 indicators that were ignored because AR just doesn't "get" F5s.

 

Anyway, so long as the NWS remains so inconsistent in its rationale for ratings (as the recent fiasco over radar measurements illustrates), then I'm no longer going to rely on the already-inaccurate NCDC/SPC database for tornado climatology. I'll just use Grazulis or my own estimates. *Rant over*

I think you are jumping to a lot of conclusions here. We just aren't there to know the specific engineering details. Even if there is very intense contextual damage, it doesn't mean much if the structures weren't well built. I mean honestly, do we actually have evidence of well-built homes with closely spaced anchor bolts being swept away? Truth is, no we don't. Until we do, i'm not going to question the rating too much.

 

I have no idea how you came to that conclusion about the Super Tuesday tornado. There is no mention of ground scouring in the survey or any other evidence of such a thing for that matter, and steel frame warehouse structures can be leveled well below EF5 intensity if there are structural flaws (similar structures with similar damage were rated EF3 in Moore last year.) The tree and chassis damage you mentioned is in no way relevant to EF5 intensity.

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In a similar vein, wasn't the Woodbury/Cherokee County, IA EF4 on 10/4/13 rated as such solely based on a grain wagon being thrown 400 yards? I don't recall there being EF4 structural damage anywhere. Also the 4/22/11 Good Friday EF4 in St. Louis was rated as such based on a single home that was swept away. There are many other examples as well.

I find it extremely ironic that the whole point of the EF-Scale was to establish a set of consistent standards applicable and readily applied equally and to all tornado cases, thereby rectifying the subjectivity of the old F-Scale. The whole imbroglio over radar data (the downgrading of Bennington and El Reno 2013) was based on the NWS establishment's view that only structural damage indicators on the EF-Scale could be used. Yet here we are with the NWS justifying its Moore 2013, Joplin/Philadelphia/El Reno 2011, and other ratings based on non-traditional, non-EF-Scale indicators like oil rigs thrown, ground scouring produced, manhole covers blown off, parking bars torn off, pavement scoured, etc. The whole situation is as absurd as it is scientifically unsound.

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Is ground scouring thought to be from the funnel itself or the debris contained therein?

Some of the debris profiles of different tornadoes may also cause more intense debris fields because of the type of debris a tornado interacts with.

160 mph winds in Oklahoma won't do as much damage as in the Southeast, namely because there is far less physical matter with weight and mass to contribute to the destruction.

When a tornado hits the South in early Spring, you've got moist soil and an abundance of pine tree missiles to fill out the debris profile of a tornado. Bad scenario.

There's a good study about this I read where they investigated this hypothesis showing some more intense damage potential with varying soil compositions/moistures.

 

There are studies being done on tree damage as well. It isn't as simple as hardwood versus softwood. Some trees within those categories respond different to wind stress. The EF scale is kind of a moving target as we get better with damage assessment.

 

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I find it extremely ironic that the whole point of the EF-Scale was to establish a set of consistent standards applicable and readily applied equally and to all tornado cases, thereby rectifying the subjectivity of the old F-Scale. The whole imbroglio over radar data (the downgrading of Bennington and El Reno 2013) was based on the NWS establishment's view that only structural damage indicators on the EF-Scale could be used. Yet here we are with the NWS justifying its Moore 2013, Joplin/Philadelphia/El Reno 2011, and other ratings based on non-traditional, non-EF-Scale indicators like oil rigs thrown, ground scouring produced, manhole covers blown off, parking bars torn off, pavement scoured, etc. The whole situation is as absurd as it is scientifically unsound.

 

So what? Don't you think these are being added and researched all the time? Scouring is a little subjective, but the others can be measured to some extent.

 

The EF scale contains the words damage indicators for a reason. Anything can be a damage indicator. We just need to establish what damage occurs at what wind speeds.

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So what? Don't you think these are being added and researched all the time? Scouring is a little subjective, but the others can be measured to some extent.

 

The EF scale contains the words damage indicators for a reason. Anything can be a damage indicator. We just need to establish what damage occurs at what wind speeds.

Please read my other post as well (plus Enso's). I'm not arguing against adding indicators to the original EF indicators; in fact, I'm for it. I'm just against the whole inconsistent manner in which the NWS is going about rating tornadoes. The NWS shouldn't be accepting single damage indicators for EF2, EF3, EF4 ratings in some cases but not in others (such as this potential EF5 case). It should be consistently applying its own standards, and include radar data to boot.

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That gets into office to office differences on whether to factor in non-traditional indicators.  2012 Henryville ripped up large chunks of concrete/boulders and tossed it some distance but Louisville didn't seem to factor it in or at least wasn't overly impressed.  

 

Are you talking about the large chunks of asphalt torn from Rt. 135 north of Palmyra, or is this something else? I don't recall hearing of concrete or boulders.

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Please read my other post as well (plus Enso's). I'm not arguing against adding indicators to the original EF indicators; in fact, I'm for it. I'm just against the whole inconsistent manner in which the NWS is going about rating tornadoes. The NWS shouldn't be accepting single damage indicators for EF2, EF3, EF4 ratings in some cases but not in others (such as this potential EF5 case). It should be consistently applying its own standards, and include radar data to boot.

 

But that's not what is happening here. There was an area that could have been EF5, and was deemed not to be after a thorough survey. They didn't toss just one damage indicator, at least from the information I have available to me.

 

The radar issue though is a different story, that goes way above the heads of any of us local WFOs.

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I'm not sure you truly appreciate how strong and rare an EF4 is. The size of the city has nothing to do with the rating. Greensburg has a population under 1,000. Parkersburg under 2,000. Hackleburg had winds estimated at 210 mph, Greensburg 205 mph, Vilonia 190 mph. They were all strong, some just stronger than others.

It's quite possible, given the lack of radar and other data for most of the past few hundred years (especially before the 1970s and modern Doppler later on), that the true number of violent tornadoes is underestimated, especially for recent years on the Great Plains, given the depopulation/demise of that region's family farms since the Dust Bowl. Some studies have suggested that most tornadoes are EF2+ capable, so more violent tornadoes than are currently documented are likely to have occurred.

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It's quite possible, given the lack of radar and other data for most of the past few hundred years (especially before the 1970s and modern Doppler later on), that the true number of violent tornadoes is underestimated, especially for recent years on the Great Plains, given the depopulation/demise of that region's family farms since the Dust Bowl. Some studies have suggested that most tornadoes are EF2+ capable, so more violent tornadoes than are currently documented are likely to have occurred.

 

I agree to some extent. But even in 2011 there were only 23 EF4/5 out of over 1700 tornadoes. That's pretty rare. I don't think the tornadoes that tear up farmland and hit nothing are numerous enough to really make violent tornadoes all that more common.

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It's quite possible, given the lack of radar and other data for most of the past few hundred years (especially before the 1970s and modern Doppler later on), that the true number of violent tornadoes is underestimated, especially for recent years on the Great Plains, given the depopulation/demise of that region's family farms since the Dust Bowl. Some studies have suggested that most tornadoes are EF2+ capable, so more violent tornadoes than are currently documented are likely to have occurred.

 

It's not just possible, it's absolutely certain that we underestimate the number of violent tornadoes. It's just a matter of by how much. They're still fairly rare as a percentage of total tornadoes, though, even if we're significantly underestimating their frequency (as we likely are). And here's the paper you're talking about.

 

https://ams.confex.com/ams/24SLS/techprogram/paper_141821.htm

 

And the relevant graphs. Frequency based on DOW-observed wind speed range is solid bars, official damage-based rating frequency is hatched.

 

g5NYaLn.png

 

SFkDkre.png

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Couple of videos of the tornadoes themselves. First one is the Louisville, MS EF4.

 

This "chaser" video of Tupelo tornado shows some remarkably idiotic behavior. Perfect guide on how NOT to chase. Good thing he put his seat belt on, cause that will definitely save you from an EF3 wedge  :rolleyes: . He is very lucky that he only got clipped by the outer edge of that beast. Not recommended if this kind of thing makes your blood boil. 

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I have to throw one thing into the ring about the manhole covers: the wind engineers calculated the winds needed to pull them out of the ground. I was watching a video a few weeks ago (I need to find it back), where they talked about this and the other unusual instances of damage they used to rate the Joplin tornado. I'm recalling this from memory so correct me if I'm wrong.

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I have to throw one thing into the ring about the manhole covers: the wind engineers calculated the winds needed to pull them out of the ground. I was watching a video a few weeks ago (I need to find it back), where they talked about this and the other unusual instances of damage they used to rate the Joplin tornado. I'm recalling this from memory so correct me if I'm wrong.

 

Partha Sarkar from Iowa State calculated the wind speeds for the manhole covers & parking stops, and I believe he arrived at roughly 205 mph for both.

 

Edit - Via Joplin Globe:

 

The tornado had wind speeds of approximately 200-plus mph. The wind speeds were calculated by Partha Sarkar, professor of wind engineering at Iowa State University in Ames, who observed that man-hole covers were lifted from the ground and that concrete parking stops had been moved by the tornado near St. John’s Regional Medical Center.
 
Using their weight and other atmospheric factors, he calculated what it would take to move them.
 
“For the manhole covers, it barely exceeds 200 mph. It’s at least that much. With the parking stops, they are in the 205 mph range,’’ he said.

 

 

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