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

[andyhb]

I don't just mean EF4 to EF5 either. I mean how many times are tornadoes pushed from EF2 to EF3 or EF1 to EF2? Nobody gets up in arms about the consistency of the system then. The only reason people care is because it's the high end of the scale.

 

I could throw in the example of the April 2nd, 2006 tornadoes in Western TN when people thought the Newbern/Bradford, TN tornadoes might have gotten an F4 rating instead of F3 due to the damage that occurred. It was then found that the homes they completely destroyed/partially swept away were very poorly anchored and it was accepted openly.

[OceanStWx]

Lackawanna, NY?  lol

 

Oops, I was thinking OU. And didn't even read that right in your name.

[hm8]

Lackawanna, NY? lol

Secret tornado capital

[Ensō]

 

I don't just mean EF4 to EF5 either. I mean how many times are tornadoes pushed from EF2 to EF3 or EF1 to EF2? Nobody gets up in arms about the consistency of the system then. The only reason people care is because it's the high end of the scale.

 

So what are you proving with this? That people pay more attention to stronger tornadoes than to weaker ones? Yes, they do. Does that invalidate anything that any of us has said? This is a strawman, as was the previous post I responded to. You obviously disagree with those of us who feel that an EF5 rating was appropriate. That's cool. You have your opinion just as we have ours. But don't act like it's just overzealous weenies throwing a temper tantrum.

 

What I'm interested in is accurately reflecting the intensity of tornadoes. If there's an EF2 tornado that was overrated as an EF3, I would have a problem with that just as I have a problem with a tornado that I feel is underrated. If you have any examples of tornadoes that have arguably been overrated, weak or otherwise, you're welcome to share them. Otherwise it adds nothing to the discussion.

 

Do I take more notice of this tornado than I would of some random EF1 or EF2? Absolutely. So does literally everyone else in the weather community. People care about violent tornadoes because they're rare, historic and pose a serious risk to life and property. I think it's especially important that we get those ratings right for those reasons. Obviously the NWS doesn't just trot out bumbling idiots to do their surveys. They know what they're doing, and they're undoubtedly better trained and more experienced than most of us are. But that doesn't mean they're above reproach.

[WEATHER53]

I am a real layman on this but ask in all seriouness.

When I have seen the houses swept off the foundation, the bit and pieces of the house are scattered like a gigantic weed wacker went through. So my question is how small can the tornado vortexs get? Small enought to almost "scour" out the house?

[Ensō]

I am a real layman on this but ask in all seriouness. When I have seen the houses swept off the foundation, the bit and pieces of the house are scattered like a gigantic weed wacker went through. So my question is how small can the tornado vortexs get? Small enought to almost "scour" out the house?

 

I'm not entirely sure what you mean by "scouring out" a house, but subvortices in tornadoes can be extremely small - even just a few yards in diameter. That's why you'll occasionally see one home that's completely swept away sitting next to a home with only modest damage. Here's a famous example from Fujita's work on the 5/11/70 Lubbock, TX F5.

 

 

As another example, this is extreme vegetation damage from the 1990 Plainfield, IL F5. The intense core of the tornado (visible as the bright streak in the middle) contracted to just 10 meters (~33 feet) in diameter as it produced this damage.

 

[SluggerWx]

How do you all feel that storm speed contributes to a tornado's damage potential?

We look at wind speed, but what about forward motion?

Do 165 mph winds in a tornado moving at 30mph have more destructive potential than 165 mph winds moving at 50+ mph if they were to take the same path?

Or, is storm motion/speed already being calculated in wind speed velocity scans?

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[thewxmann]

I disagree more strongly with this rating than I do the Tuscaloosa tornado. Although the TCL tornado caused a massive amount of intense damage and almost certainly was capable of causing EF5 (and absolutely would have been rated as such at times in the past), I don't think it caused any damage that I'd consider clear-cut EF5 when you factor in the context. In Vilonia, I thought a few areas showed what was quite clearly EF5 damage. Frankly I'd say some of the damage was comparable to the EF5-rated damage instances that we saw from the Hackleburg or Smithville tornadoes, just over a considerably smaller area.

 

I sort of agree with your first point though, and that's one of the objections I have. We've effectively changed what an EF5 tornado is, and that doesn't make sense to me from a historical standpoint.

 

I am a bit surprised by the lack of ef-5, it is almost getting to the point where the scale is more about building code and less about winds and damage.

One of the main problems I have, which I'm sure has been brought up here (and has elsewhere) with skimming over the thread, is the apparent lack of attention paid to the surroundings of where the DI is analyzed. With this tornado in Vilonia, everything that you look for in an extremely violent tornado is there, unlike several other cases (especially pre-EF scale) that were given F/EF5 ratings.

 

This. This tornado had damage comparable to Moore, Hackleburg, Smithville, etc. It was definitely a high-end tornado. Tuscaloosa was more borderline, and the NWS had legitimate reasons for keeping it EF4 in some places (lack of high-end vehicle damage in PG, for example). Here we had severe wind rowing, ground scouring, mangled vehicles -- even if the houses weren't extremely well constructed, there are plenty of indicators of a high-end tornado.

 

It's very clear that we would have to see something on the level akin to Joplin for LZK to assign an EF5 rating. It's one of the more conservative offices for sure, on the level of SGF, FFC, and FWD.

[JoMo]

I am a real layman on this but ask in all seriouness. When I have seen the houses swept off the foundation, the bit and pieces of the house are scattered like a gigantic weed wacker went through. So my question is how small can the tornado vortexs get? Small enought to almost "scour" out the house?

 

There's... oddities... when tornadoes go through areas. This is a pic from Joplin. If you can see the small white house with the red roof near the center of the picture, it isn't nearly as damaged as the houses immediately to it's south (bottom right of pic) and west (left side of pic). In fact, it looks like it didn't even lose any of it's roof decking and it still has a small overhang attached to it's west side that should have easily snapped off. You can clearly see the houses to it's west and south have suffered at least EF-2 to EF-3 type damage with many of the houses only having interior walls left. The houses to the east across the street that aren't pictured suffered similar damage as well as the houses at the top and top right of the picture. 

 

The question is... why did this house have a lot less damage when compared to other houses that were just feet away? Did it have to do with the construction of the house compared to the other houses? Was it due to a vortex missing the house? Luck? A combination of the above factors?

 

 

 

I looked up this house in Google Maps to see if there was anything special about it compared to the other houses near it and I just noticed the new "Timeline" type feature on Google Maps.  This house looks to have been rebuilt in the same place as it's a bit longer, but they look to have rebuilt it much the same way it was in 2007. Wow, that's weird being able to see Joplin in 2007, then in 2012, 2013 after the tornado......

[Master of Disaster]

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.      

 

Tim Marshall mentioned this at the Severe Storms Conference a year or two ago. There is a VERY strict set of criteria they look for with EF5s. Ground scouring, pulverization of home debris, debarked shrubs are three of the major ones. In fact he mentioned during his presentation that they have surveyed slabbed homes and set the intensity at EF4 based on a lack of those three indicators. 

 

I am not sure the pulverization of debris should be a factor. That seemed to come up after Jarrell Texas where that was noted but how can you compare any other F/EF5 to what may very well be the strongest F5 tornado ever recorded? 

 

Here is his presentation. Def worth taking a look. http://www.norman.noaa.gov/nsww/wp-content/uploads/2012/03/LaDue_NSWW2012.pdf

[AtticaFanatica]

I'm kinda interested on this whole radar estimated winds issue.  Why did the powers that be decide not to use any radar winds for classification?  If we are to be as scientific and accurate as possible, shouldn't we use all data available?  Is there some concern that using radar winds will result in a larger disparity from the original F scale?  Is there some concern that there will be a disparity in ratings between regions, as in more mobile radar on plains outbreaks vs. southeast outbreaks?

The decision came from the top and the reasons were not purely scientific, though there are legitimate concerns there as well.

[AtticaFanatica]

The concerns about this rating and the desire for an accurate intensity climatology are laudable, but IMO the ship has sailed on the latter. I think the community simply overestimates the precision the system has in determining tornado wind speeds. There's some skill there, but not in consistently getting it correctly into one of six categories.

One tornado being rated EF4 vs EF5 has near zero meteorological significance, though I understand there is historical significance.

[Buckeye05]

Tim Marshall mentioned this at the Severe Storms Conference a year or two ago. There is a VERY strict set of criteria they look for with EF5s. Ground scouring, pulverization of home debris, debarked shrubs are three of the major ones. In fact he mentioned during his presentation that they have surveyed slabbed homes and set the intensity at EF4 based on a lack of those three indicators. 

 

I am not sure the pulverization of debris should be a factor. That seemed to come up after Jarrell Texas where that was noted but how can you compare any other F/EF5 to what may very well be the strongest F5 tornado ever recorded? 

 

Here is his presentation. Def worth taking a look. http://www.norman.noaa.gov/nsww/wp-content/uploads/2012/03/LaDue_NSWW2012.pdf

I'm still very conflicted about yesterday's rating. I can see both arguments, but I really want to know the finer details regarding the foundation type/quality of anchoring before I'm convinced it was a botched survey. If they were all cut-nailed down, then I could could see the EF4 rating being legit despite the context. However, if there was anchor bolting i'm going to remain skeptical of if EF4 was appropriate, especially with all three of those hallmarks present in Vilonia. It raises the question of if there are some survey teams that only do 100% structural engineering based surveys, vs teams that factor in non-traditional DIs that can suggest wind speeds higher than what the house actually failed at. It seem that the presentation that you posted is more supportive of the second approach.

[Ensō]

Tim Marshall mentioned this at the Severe Storms Conference a year or two ago. There is a VERY strict set of criteria they look for with EF5s. Ground scouring, pulverization of home debris, debarked shrubs are three of the major ones. In fact he mentioned during his presentation that they have surveyed slabbed homes and set the intensity at EF4 based on a lack of those three indicators. 

 

I am not sure the pulverization of debris should be a factor. That seemed to come up after Jarrell Texas where that was noted but how can you compare any other F/EF5 to what may very well be the strongest F5 tornado ever recorded? 

 

Here is his presentation. Def worth taking a look. http://www.norman.noaa.gov/nsww/wp-content/uploads/2012/03/LaDue_NSWW2012.pdf

 

Exactly. That's the context I've been harping about that is most useful in discriminating EF4 vs. EF5 intensity, and all three were present in Vilonia, as was very pronounced wind rowing - not necessarily an EF5 indicator but certainly supportive of an exceedingly violent tornado. The same goes for extreme tree damage - not just some debarking, but complete debarking/denuding and stubbing of large trees (Joplin being probably the most striking example of this that I've ever seen). There are so few homes of "superior" construction that it's extraordinarily difficult to rate a tornado EF5 without also looking at context to see whether a higher rating is supported, and that's why I keep wondering whether some surveys get too hung up on construction quality and fail to see the bigger picture. Maybe they have a very good reason for going EF4, but I'm skeptical.

 

Re: debris granulation, it doesn't have to be to quite the extent of Jarrell, where literally everything was ground up to the point that you couldn't hardly see any debris. The 2008 Parkersburg tornado is a textbook example of the kind of debris granulation they look for, you can see it a little bit in this survey.

 

http://www.crh.noaa.gov/images/dmx/parkersburg/Parkersburg-Storm-Damage-Survey.pdf

[Ground Scouring]

On another note, the outbreak continues to look more and more impressive as survey data come in.

• NWS Huntsville has found two EF3s in Cullman and Limestone County. Two EF1s have been found in Franklin and Mdison counties. Possible tornado tracks in Etowah and DeKalb counties are being surveyed.
• NWS Birmingham has found an EF3 in Russell and Lee counties, plus two EF2s and an EF1 in Jefferson County. The NWS is also surveying possible tornado tracks in Blount, Pickens, Lamar, Marion, and Fayette counties.
• NWS Jackson has found a long-tracked EF3 that went through Hinds-Rankin-Scott County tornadoes, in addition to the shorter-lived EF3 in Scott County. Seven EF1s have been found in Warren, Hinds, Newton, Crawford, Lowndes and Madison counties. Three EF2s hit Newton and Lowndes counties.

[Ground Scouring]

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.

Many surveys have ignored or not mentioned important details; for example, the Kellerville, TX (1995), survey overlooked a home that was totally swept away; the Smithville did not mention the foot-deep ground scouring outside town, documented by ExtremePlanet (2011); did not mention the complete stripping of all vegetation and topsoil from NE OK on May 5, 1960 (mentioned in Grazulis's F5-F6 booklet); etc. As for Clinton, take a good, long look at the following photographs (there are eleven pages of them) and see whether you still disagree with me.

 

http://mike-photos.smugmug.com/gallery/4294521_qnRdX#!i=251689013&k=eAqSS

 

You will find not only ground scouring and trailer chassis, but also those two-foot-thick trees debarked and/or snapped just above ground level; vehicles and trailers thrown long distances and mangled; low shrubs shredded/possibly debarked; the boat factory utterly flattened as were the steel factories at Wheatland and Barrie in 1985; etc. The debarking is a bit hard to see but is evident in the background of some of the images showing the boat factory. I'll admit that the scouring is not as strongly defined as in some other tornadoes, but remember, this tornado occurred in the middle of winter and in a region that has less-sandy/loose soils than in, say, OK or MS. The empty foundations came from an aerial by a Little Rock-based news outlet, but I can't find a working link to it.

[Ensō]

The Clinton tornado was very intense at times and not far off from EF5, but I think EF4 is the right call and I don't see anything in those photos that changes my mind. Admittedly I didn't look at every photo there, but I don't see anything that looks like legitimate ground scouring or intense damage to low-lying shrubs, etc. From what I've seen there weren't even that many homes fully swept away, though there were a number of them leveled.

[Buckeye05]

Many surveys have ignored or not mentioned important details; for example, the Kellerville, TX (1995), survey overlooked a home that was totally swept away; the Smithville did not mention the foot-deep ground scouring outside town, documented by ExtremePlanet (2011); did not mention the complete stripping of all vegetation and topsoil from NE OK on May 5, 1960 (mentioned in Grazulis's F5-F6 booklet); etc. As for Clinton, take a good, long look at the following photographs (there are eleven pages of them) and see whether you still disagree with me.

 

http://mike-photos.smugmug.com/gallery/4294521_qnRdX#!i=251689013&k=eAqSS

 

You will find not only ground scouring and trailer chassis, but also those two-foot-thick trees debarked and/or snapped just above ground level; vehicles and trailers thrown long distances and mangled; low shrubs shredded/possibly debarked; the boat factory utterly flattened as were the steel factories at Wheatland and Barrie in 1985; etc. The debarking is a bit hard to see but is evident in the background of some of the images showing the boat factory. I'll admit that the scouring is not as strongly defined as in some other tornadoes, but remember, this tornado occurred in the middle of winter and in a region that has less-sandy/loose soils than in, say, OK or MS. The empty foundations came from an aerial by a Little Rock-based news outlet, but I can't find a working link to it.

Yeah I don't see anything that could be called scouring, just muddy spots that could be anything. And it's not like every steel frame warehouse is built to the same standard. We don't know how it was engineered. I'm not sure how the snapped large trees and twisted chassis are relevant, as iv'e seen EF2s do both of those things. Aerial pics of bare slabs tell us nothing without details of the anchoring. Seems like conjecture to me.

[Buckeye05]

Video showing the formation of the Quapaw/Baxter Springs tornado. 

[harrisale]

The concerns about this rating and the desire for an accurate intensity climatology are laudable, but IMO the ship has sailed on the latter. I think the community simply overestimates the precision the system has in determining tornado wind speeds. There's some skill there, but not in consistently getting it correctly into one of six categories.

One tornado being rated EF4 vs EF5 has near zero meteorological significance, though I understand there is historical significance.

 

Great points. I think most concerns would relate simply to historical signficance, as well as issues that maybe people would possibly donate more to tornado relief for an EF5 vs EF4.

 

In terms of an accurate climatological database of tornado events, things have been so inconsistent since tornado records started that this one particular rating does not skew the dataset significantly one way or another. EF4 and EF5 tornados are both extremely rare and powerful. When it comes to forecasting, we can predict that a particular setup will produce a few tornados, numerous tornados, strong tornados or weak tornados, we don't really have the capacity to predict whether an EF4 or EF5 will occur. So in terms of attempting to predict the outcome of severe systems when using analogs etc., the final ratings makes very little difference.

 

If we really wanted an accurate database of tornado strength for the purpose of weather prediction, we would likely need to start the database over from scratch, using a different data collection method (such as mobile radar) to collect tornado windspeeds. But of course, that isn't exactly practical.

[Ground Scouring]

Yeah I don't see anything that could be called scouring, just muddy spots that could be anything. And it's not like every steel frame warehouse is built to the same standard. We don't know how it was engineered. I'm not sure how the snapped large trees and twisted chassis are relevant, as iv'e seen EF2s do both of those things. Aerial pics of bare slabs tell us nothing without details of the anchoring. Seems like conjecture to me.

I forgot to mention that the aerials showed LARGE, bare foundations with NO or VERY LITTLE debris left within hundreds of yards of the foundations. I'm also considering the weight of the evidence, such as the sustained intensity of the radar couplet near Atkins and Clinton, the shredding/twisting of the vehicles and chassis, the tree damage, etc. I'm not sure how well the steel boat factory (and the empty-slabbed structures) was constructed, but note that for a factory of its size, it didn't leave behind a lot of large debris except that which appears to have been well anchored. The remaining large debris is not very high and is mangled unrecognizably and/or severely. And many large objects near the factory appear to have been carried fairly long distances.

[Buckeye05]

I forgot to mention that the aerials showed LARGE, bare foundations with NO or VERY LITTLE debris left within hundreds of yards of the foundations. I'm also considering the weight of the evidence, such as the sustained intensity of the radar couplet near Atkins and Clinton, the shredding/twisting of the vehicles and chassis, the tree damage, etc. I'm not sure how well the steel boat factory (and the empty-slabbed structures) was constructed, but note that for a factory of its size, it didn't leave behind a lot of large debris except that which appears to have been well anchored. The remaining large debris is not very high and is mangled unrecognizably and/or severely. And many large objects near the factory appear to have been carried fairly long distances.

Yeah i'm not having this conversation anymore. I'm just not terribly impressed by any of that.

[Ground Scouring]

Yeah i'm not having this conversation anymore. I'm just not terribly impressed by any of that.

Difference of opinion is fine. I'm not basing my views on feelings, but rather what I see to be the blend of the evidence. The points have already been rehashed by others who have debated the Vilonia rating as well.

[blackjack123]

Agree snowflake22.

[Arnold214]

The concerns about this rating and the desire for an accurate intensity climatology are laudable, but IMO the ship has sailed on the latter. I think the community simply overestimates the precision the system has in determining tornado wind speeds. There's some skill there, but not in consistently getting it correctly into one of six categories.

One tornado being rated EF4 vs EF5 has near zero meteorological significance, though I understand there is historical significance.

I'm not really sure we should actually have a 6-category scale. We're just not that good at this point. Obviously, we can't go back, but a 3 or 4 category scale probably fits our current skill set better. Perhaps something like weak, moderate, strong (and maybe an "extreme" category for the no-doubt, creme de la creme cases) and leave it at that.

[AtticaFanatica]

I'm not really sure we should actually have a 6-category scale. We're just not that good at this point. Obviously, we can't go back, but a 3 or 4 category scale probably fits our current skill set better. Perhaps something like weak, moderate, strong (and maybe an "extreme" category for the no-doubt, creme de la creme cases) and leave it at that.

Couldn't agree more. I think the mobile radar data support using three categories: weak, moderate, and strong. Other tornado scientists I respect have said the same, though I don't think anyone's said it publicly.

[ineedsnow]

Thats nuts I really think this was a ef 5

Incredible story from Arkansas. Pickup truck reportedly carried 27 miles by Mayflower-Vilonia tornado last Sunday evening.

http://www.usatoday.com/story/weather/2014/05/01/tornado-truck-carried-arkansas/8571637/?utm_source=dlvr.it&utm_medium=twitter

[Buckeye05]

Thats nuts I really think this was a ef 5

 

I am seeing this story everywhere. Honestly, that is such an incredible claim that i'm a little hesitant to believe it. There is a similar rumor floating around about the 1998 Forgotten F5, but I don't think it has ever been proven. I'd want to see pictures/confirmation through a reliable source for this. One would think that a vehicle exposed to violent winds/debris for such a long time would just disintegrate. If it ends up being true, then that has to be the farthest documented distance a vehicle has ever been carried by a tornado. Crazy.

 

Edit: Typo

[Arnold214]

I am seeing this story everywhere. Honestly, that is such an incredible claim that i'm a little hesitant to believe it. There is a similar rumor floating around about the 1998 Forgotten F5, but I don't think it has ever been proven. I'd want to see pictures/confirmation through a reliable source for this. One would think that a vehicle exposed to violent winds/debris for such a long time would just disintegrate. If it ends up being true, then that has to be the farthest documented distance a vehicle has ever been carried by a tornado. Crazy.

Edit: Typo

Just thinking about the physics involved here, I find it very hard to believe that a truck could remain aloft over that distance. It would eventually be spit out much sooner than that. The updraft velocities would have to be astronomical and still be lucky enough for the truck to not be centrifuged out at some point.

[WEATHER53]

The questions I posed last night, and thanks for your answers, are continuing. Often with these homes it does not look like they have been "blown" to pieces but rather "beat" to pieces. My imagery is like a giant old fashioned cloth mop just whirling at 175mph. One guy said smallest sub vortexes are a couple yards in diameter but I envision an almost mop like structure where drinking straw size elements are rotating furiously creating the weed wacker effect I mentioned last night? Am I proven to be way off base with this concept?