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

[blackjack123]

It appears to be relatively well-built but I can't really tell and some of you probably know more about building construction than I do.

[Buckeye05]

The info comes straight from the survey:

Link

 

And then there's this image showing a large, brick-built, newer-looking building (a bank?) that was completely leveled and not even listed as a damage point by LZK:

 

Yes but I don't think that statement applies to the E Wicker St home. The survey lists the DOD as "Destruction of engineered and/or well constructed residence; slab swept clean", indicating that the slab was left clean as a result of the tornado rather than cleanup. If there was a big debris pile there at one time, the DOD probably would have read "All walls collapsed."

 

And as a reply to blackjack123, the house appears to be well-built due to the presence of closely spaced anchor bolts complete with washers/nuts (you can see them sticking out of the foundation perimeter in the photo). This type of house damage in combination with supporting context is usually rated EF5 (as it was in Moore last year). The comments section for that damage point even mentions that the home was well-anchored, so that's why we are at a loss for what the reasoning was there.

[Ensō]

The info comes straight from the survey:

http://www.srh.noaa.gov/lzk/?n=anchor0514.htm

 

And then there's this image showing a large, brick-built, newer-looking building (a bank?) that was completely leveled and not even listed as a damage point by LZK:

 

 

This was formerly Hook's Fish House. I wouldn't automatically assume it was well-built, though it may well have been.

 

 

http://www.loopnet.com/Listing/17317943/1117-Main-Street-Vilonia-AR/

[TropicalAnalystwx13]

I could see some uncertainty being the reason they kept it an EF4. The home in question with its foundation swept clean looks to have been literally swept clean (there's a broom in the picture). In the background, downed trees have already been cut up. Given that the surveyors didn't arrive in Vilonia until 2 days after the tornado, they have no idea how the foundation looked beforehand. If the foundation looked like that beforehand, definitely EF5 damage.

 

And so I have a question to ask: has anyone ever seen jersey barriers (which weigh 5000 pounds) rolled over or moved several feet by a tornado? This was initially listed as an EF4 damage point in the .kmz file, but now it's listed as "UNKNOWN".

 

[blackjack123]

Hal Sellers is the name of the guy who owned that home listed in that picture. Type in under a google search Hal Sellers Vilonia tornado.

[OceanStWx]

The NWS Little Rock makes their case rest upon the fact that the well-built homes supposedly had debris left on their foundations immediately after the storm. Well, LZK should tell that to Tim Marshall et al. who found that several of the homes in Moore after 05/20/2013 had their bare slabs partially covered by debris from other destroyed structures. Thus, the mere presence of debris on the foundation is not necessarily due to/from/related to the home itself, but may have come from other structures, thus proving that debris does not mean the damage was not EF5 in intensity.

 

Likewise the points mentioned in this thread don't necessarily mean the damage was EF5 in intensity either.

 

Reviewing the survey, it appears at least a couple homes were swept clean and were properly anchored. According to the EF scale that translates to expected winds of 200 mph. 200 mph is not an EF5 (which is why that line about additional strengthening of the structure is important).

 

It's a very literal interpretation of the EF scale, but as several people have mentioned, we're basically splitting hairs at this point. We're not that good to differentiate between 200 mph and 201 mph. Even the difference between a 190 mph EF4 and 205 mph EF5 is negligible.

 

[OceanStWx]

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.

 

Exactly. I mean we basically forecast this way in the first place. SPC's discussion differentiate between "a few tornadoes," "strong," and "violent" or "long-tracked" in nature. We do research based on weak tornadoes versus significant (EF2+). Within the EF scale itself we already break down tornadoes into weak (EF0-1), strong (EF2-3), and violent (EF4-5).

 

The practical part of this (forecasting/warning) is already done in a three category style. It's the bookkeeping where things become murky.

 

[Ground Scouring]

This was formerly Hook's Fish House. I wouldn't automatically assume it was well-built, though it may well have been.

 

http://www.loopnet.com/Listing/17317943/1117-Main-Street-Vilonia-AR/

Restaurants of the type shown here aren't usually engineered to withstand even high-end EF4 winds, so most likely it wasn't well anchored.

[Hoosier]

Nothing will convince me otherwise. This tornado deserved an EF5 rating and like I said no one will convince me otherwise. Heck even the Washington Illinois tornado last fall was a good candidate for an EF5 rating. Oh but EF5's don't happen in November or in Arkansas. Other factors in some tornadoes despite construction of homes that were rated high-end EF4 have been even more impressive than some recent EF5 tornadoes. That picture above seals the deal for an EF5 rating. There is more than an argument.

 

 

There can be legit debate about the rating but this implied conspiracy stuff doesn't really add anything.  For one, I can't see what the motivation would be especially since we are talking about a region that is no stranger to violent tornadoes.

[Ensō]

Restaurants of the type shown here aren't usually engineered to withstand even high-end EF4 winds, so most likely it wasn't well anchored.

 

Exactly. Looks are often deceiving. It's hard to say without knowing the actual details of the building's construction, but I'd be a bit skeptical. Still surprised there wasn't even a damage point there though.

[andyhb]

It appears to be relatively well-built but I can't really tell and some of you probably know more about building construction than I do.

 

Well then I would stop with some of the conspiracy game you are playing.

 

Edit: I see Hoosier already got you on that.

[thewxmann]

Likewise the points mentioned in this thread don't necessarily mean the damage was EF5 in intensity either.

 

Reviewing the survey, it appears at least a couple homes were swept clean and were properly anchored. According to the EF scale that translates to expected winds of 200 mph. 200 mph is not an EF5 (which is why that line about additional strengthening of the structure is important).

 

It's a very literal interpretation of the EF scale, but as several people have mentioned, we're basically splitting hairs at this point. We're not that good to differentiate between 200 mph and 201 mph. Even the difference between a 190 mph EF4 and 205 mph EF5 is negligible.

 

 

Well I'm not so sure there was additional strengthening in the slabbed structures in Hackleburg, Moore, etc either. Again, lots of built in subjectivity to the ratings, especially on the high end.

[OceanStWx]

Well I'm not so sure there was additional strengthening in the slabbed structures in Hackleburg, Moore, etc either. Again, lots of built in subjectivity to the ratings, especially on the high end.

 

First, there is some subjectivity throughout the entire scale, not just the high end.

 

And are you or aren't you sure there was additional strengthening measures in Hackleburg and Moore? My point is just that taking the scale literally, well built homes swept clean are rated at 200 mph (which is EF4). People here are arguing over 1 mph, and we really don't know enough to make that differentiation one way or the other.

[OceanStWx]

I think people forget too that we had a gap from 1999 (Moore) to 2007 (Greensburg) without an EF5. It's not like EF5s are really becoming less common because of the rating system.

[andyhb]

I think people forget too that we had a gap from 1999 (Moore) to 2007 (Greensburg) without an EF5. It's not like EF5s are really becoming less common because of the rating system.

 

Well the Girard tornado on 5/4/03 is another deal but that's a separate discussion.

[Buckeye05]

Don't forget Harper County, KS 2004. Surveyors came very close to handing out an F5 rating there, but backed out due to the slow forward movement of the tornado. Also, it is not true that homes need special reinforcements beyond sufficient anchor bolting to receive an EF5 rating. The rating in Moore last year was mainly based on 10 well-anchored homes that were reduced to bare slabs. Ortega even mentioned that there were a few straight-nailed wall connections between the bolts, but they decided that EF5 was more appropriate than EF4 due to some sill plate removal,  the presence of bent anchor bolts, and context indicative of an extremely violent tornado. The very same thing can be said about the ratings in Greensburg, Parkersburg, and Smithville. Well-anchored homes reduced to slabs + supporting context = EF5 damage. Calling a bare slab with bolts around the perimeter high EF4 is a stretch to say the least.

[OceanStWx]

Don't forget Harper County, KS 2004. Surveyors came very close to handing out an F5 rating there, but backed out due to the slow forward movement of the tornado. Also, it is not true that homes need special reinforcements beyond sufficient anchor bolting to receive an EF5 rating. The rating in Moore last year was mainly based on 10 well-anchored homes that were reduced to bare slabs. Ortega even mentioned that there were a few straight-nailed wall connections between the bolts, but they decided that EF5 was more appropriate than EF4 due to some sill plate removal,  the presence of bent anchor bolts, and context indicative of an extremely violent tornado. The very same thing can be said about the ratings in Greensburg, Parkersburg, and Smithville. Well-anchored homes reduced to slabs + supporting context = EF5 damage. Calling a bare slab with bolts around the perimeter high EF4 is a stretch to say the least.

 

No, verbatim it is high EF4. Supporting context is what brings bare slabs to EF5, or at least that's how it should work when taking the EF scale literally. I'm not making this stuff up. Expected winds for a bare slab, well-built home is 200 mph. EF4.

 

And regardless of whether they were close or not, there were no tornadoes rated F5 from 1999 to 2007. When I've heard multiple times in this thread that F5 ratings were much more liberal before the transition to the EF scale. People can't have their arguments both ways. There will always be storms that could go either way, but the fact remains we've had 7 EF5s in the last 3 years and 3 in the previous 12.

[Ensō]

No, verbatim it is high EF4. Supporting context is what brings bare slabs to EF5, or at least that's how it should work when taking the EF scale literally. I'm not making this stuff up. Expected winds for a bare slab, well-built home is 200 mph. EF4.

 

And regardless of whether they were close or not, there were no tornadoes rated F5 from 1999 to 2007. When I've heard multiple times in this thread that F5 ratings were much more liberal before the transition to the EF scale. People can't have their arguments both ways. There will always be storms that could go either way, but the fact remains we've had 7 EF5s in the last 3 years and 3 in the previous 12.

 

So why do you pick that particular span? I haven't seen anyone mention that tornadoes are being rated more conservatively now than during that particular period (or any specific period, really). Four of those EF5s came within a few hours of one another. There were also seven (or six depending on the source you use) F5s in as many hours on 4/3/74, so what does that prove? Nothing other than that statistics and raw numbers can be heavily skewed by singular events. It's not about the sheer number of tornadoes given a particular rating. It's about how those ratings are derived, and it's about how inconsistently those ratings are assigned from WFO to WFO, event to event and even surveyor to surveyor.

 

It's one thing when what warranted an F5 rating well in the past (as in, decades ago) isn't even close to what's needed for an EF5 rating today - our understanding of tornadoes and of construction practices changes over time and we've tried to incorporate that into the surveys. Fair enough. I'm happy that something like this doesn't get an EF5 rating as it did back in the day:

 

 

..But the damage that receives an EF4 or EF5 rating today in one WFO or from one particular survey team often doesn't remotely resemble what's needed to garner the same rating from another WFO or survey team. There appears to be little to no consistency, and it's pretty clear that the rating a tornado receives depends heavily on who conducts the surveys. And that isn't just applicable to the borderline high-end EF4/5 cases, it applies across the board. If you don't think that's a problem, that's fine, but I do and I don't think I'm the only one.

 

And as Stebo said earlier in this thread, we seem to have reached a point where it seems we no longer do damage surveys, we do construction surveys. Those things are certainly related, but they are not the same.

 

Also, this is not to suggest that similar inconsistencies haven't been commonplace since the very beginning, because they most likely have. Rather, the point is that we have the ability to substantially reduce that inconsistency, and that was one of the primary goals of the EF-scale. Yet I think it's obvious that hasn't happened to this point.

[TropicalAnalystwx13]

I emailed the NWS LZK webmaster this morning about that particular house that's in debate, and this is what he said in return:

 

Hello Cody:

 

While there were anchor bolts at that house, there was some question as to how the studs were

attached to the sill plate. A straight nailed stud will lift right out. In the end, the house was rated at 190 mph,
or high end EF4.

 

Thanks for asking! Hopefully, this helps.

 

John Lewis
National Weather Service
Little Rock, Arkansas

 

[David Reimer]

It's interesting to note many of these building practices in dispute out in Arkansas are being used in new Moore homes being built today. While many have anchor bolts (more than nails) many are missing the bolts or are incorrectly installed! 

[thewxmann]

No, verbatim it is high EF4. Supporting context is what brings bare slabs to EF5, or at least that's how it should work when taking the EF scale literally. I'm not making this stuff up. Expected winds for a bare slab, well-built home is 200 mph. EF4.

 

And regardless of whether they were close or not, there were no tornadoes rated F5 from 1999 to 2007. When I've heard multiple times in this thread that F5 ratings were much more liberal before the transition to the EF scale. People can't have their arguments both ways. There will always be storms that could go either way, but the fact remains we've had 7 EF5s in the last 3 years and 3 in the previous 12.

 

That bolded statement is not necessarily correct.

 

There was a period, I would say between 2002-2007, when surveyors went extra conservative in their ratings -- due to the backlash from the La Plata incident when Marshall et. al. found that EF1-2 winds could blow a poorly anchored home off its foundation. The surveys that were conducted during post-La Plata (for high-end tornadoes at least) were truly engineering surveys rather than tornado surveys. It was not only nearly impossible to obtain an F5 rating, it was rather difficult to get an F4, simply because many homes aren't built to withstand very high winds. For instance, many of the 5/4/03 F3 tornadoes would receive an EF4 today. Westminster, TX in 2006 would receive an EF4 today. Maybe Gallatin, TN on 4/7/06 as well, and at least one of the tornadoes on 4/2/06.

 

The introduction of the EF scale in 2007 helped to rectify some of the issues, perhaps by providing a more concrete guideline on the lower and upper bound for high-end damage. Initially, offices were still gunshy... for instance, the EF4 rating on the Blue Mound, KS tornado on 2/28/07 was a big deal. The EF4 tornadoes on 3/1/07 weren't upgraded from EF3 until several months later. Over time WFO's became more comfortable with the idea of EF4, to the point now that we have some questionably high EF4 ratings (Rozel, the IA one on 10/4 last year).

[JoMo]

This is from the Baxter Springs EF-2... showing just how easily it is to blow a house off it's foundation and in this case into the street when it isn't anchored. 

 

[Buckeye05]

That bolded statement is not necessarily correct.

 

There was a period, I would say between 2002-2007, when surveyors went extra conservative in their ratings -- due to the backlash from the La Plata incident when Marshall et. al. found that EF1-2 winds could blow a poorly anchored home off its foundation. The surveys that were conducted during post-La Plata (for high-end tornadoes at least) were truly engineering surveys rather than tornado surveys. It was not only nearly impossible to obtain an F5 rating, it was rather difficult to get an F4, simply because many homes aren't built to withstand very high winds. For instance, many of the 5/4/03 F3 tornadoes would receive an EF4 today. Westminster, TX in 2006 would receive an EF4 today. Maybe Gallatin, TN on 4/7/06 as well, and at least one of the tornadoes on 4/2/06.

 

The introduction of the EF scale in 2007 helped to rectify some of the issues, perhaps by providing a more concrete guideline on the lower and upper bound for high-end damage. Initially, offices were still gunshy... for instance, the EF4 rating on the Blue Mound, KS tornado on 2/28/07 was a big deal. The EF4 tornadoes on 3/1/07 weren't upgraded from EF3 until several months later. Over time WFO's became more comfortable with the idea of EF4, to the point now that we have some questionably high EF4 ratings (Rozel, the IA one on 10/4 last year).

He has a good point though about the construction by itself without supporting context. The 2007 Blue Mound tornado swept away a farmhouse that was actually very well-bolted to it's foundation. However, the fact that a small wooden deck and an ornamental tree on the property were untouched prevented a rating higher than EF4. The only problem I have is that the context surrounding the house in question in Vilonia was very indicative of a violent tornado.

[Ensō]

This is from the Baxter Springs EF-2... showing just how easily it is to blow a house off it's foundation and in this case into the street when it isn't anchored. 

 

 

Yeah, I get the impression that some of those sliders could probably be blown off their foundations by strong straight-line wind gusts. There were a lot of those in and around Tuscaloosa, too, where homes were pushed off their foundations even well away from the center of the damage path (where winds were probably more EF1 or EF2 range.

 

I think the lesson we've learned here is that pier and beam foundations suck.

[Master of Disaster]

Don't forget Harper County, KS 2004. Surveyors came very close to handing out an F5 rating there, but backed out due to the slow forward movement of the tornado. Also, it is not true that homes need special reinforcements beyond sufficient anchor bolting to receive an EF5 rating. The rating in Moore last year was mainly based on 10 well-anchored homes that were reduced to bare slabs. Ortega even mentioned that there were a few straight-nailed wall connections between the bolts, but they decided that EF5 was more appropriate than EF4 due to some sill plate removal,  the presence of bent anchor bolts, and context indicative of an extremely violent tornado. The very same thing can be said about the ratings in Greensburg, Parkersburg, and Smithville. Well-anchored homes reduced to slabs + supporting context = EF5 damage. Calling a bare slab with bolts around the perimeter high EF4 is a stretch to say the least.

 

I think the final count was 11 homes rated at EF5 intensity in Moore with 4 of those questionable due to a loop the tornado took hitting the same homes twice.

[Ground Scouring]

Yeah, I get the impression that some of those sliders could probably be blown off their foundations by strong straight-line wind gusts. There were a lot of those in and around Tuscaloosa, too, where homes were pushed off their foundations even well away from the center of the damage path (where winds were probably more EF1 or EF2 range.

 

I think the lesson we've learned here is that pier and beam foundations suck.

That lesson actually isn't even very new. Damage surveys after the April 2, 1957, Dallas F3 tornado showed that, while many of the homes were swept away, they were constructed on piers roughly eight to 12 feet "on center" (Grazulis, 1993). Even though the tornado overturned nearby railcars, the cars weren't carried a long distance and to my knowledge there was no ground scouring, so while photogrammetric estimates *possibly* suggested low-end F4 intensity, the final rating was F3 due to the poor quality of construction. Interestingly, the pier construction has long since remained in use in some Southern areas.

[OceanStWx]

 

So why do you pick that particular span? I haven't seen anyone mention that tornadoes are being rated more conservatively now than during that particular period (or any specific period, really).

 

...But the damage that receives an EF4 or EF5 rating today in one WFO or from one particular survey team often doesn't remotely resemble what's needed to garner the same rating from another WFO or survey team. There appears to be little to no consistency, and it's pretty clear that the rating a tornado receives depends heavily on who conducts the surveys. And that isn't just applicable to the borderline high-end EF4/5 cases, it applies across the board. If you don't think that's a problem, that's fine, but I do and I don't think I'm the only one.

 

I just picked that span to point out that EF5s aren't necessarily a yearly occurrence. It is possible to have violent tornadoes that do a lot of damage that aren't EF5 in intensity. And plenty of people have mentioned in this thread that recent tornadoes would easily garner an EF5 rating in years past. That to me sounds like people think we're being too conservative now.

 

As far as consistency from WFO to WFO, do you think that there isn't consultation going on with experts? It's not like LZK goes out and gets to assign a rating without talking to experts (in many cases the same experts who assist on other large damage surveys).

[OceanStWx]

That bolded statement is not necessarily correct.

 

There was a period, I would say between 2002-2007, when surveyors went extra conservative in their ratings -- due to the backlash from the La Plata incident when Marshall et. al. found that EF1-2 winds could blow a poorly anchored home off its foundation. The surveys that were conducted during post-La Plata (for high-end tornadoes at least) were truly engineering surveys rather than tornado surveys. It was not only nearly impossible to obtain an F5 rating, it was rather difficult to get an F4, simply because many homes aren't built to withstand very high winds. For instance, many of the 5/4/03 F3 tornadoes would receive an EF4 today. Westminster, TX in 2006 would receive an EF4 today. Maybe Gallatin, TN on 4/7/06 as well, and at least one of the tornadoes on 4/2/06.

 

The introduction of the EF scale in 2007 helped to rectify some of the issues, perhaps by providing a more concrete guideline on the lower and upper bound for high-end damage. Initially, offices were still gunshy... for instance, the EF4 rating on the Blue Mound, KS tornado on 2/28/07 was a big deal. The EF4 tornadoes on 3/1/07 weren't upgraded from EF3 until several months later. Over time WFO's became more comfortable with the idea of EF4, to the point now that we have some questionably high EF4 ratings (Rozel, the IA one on 10/4 last year).

 

Regrading these bolded points, if a home isn't built to withstand high winds how can you rate the winds any higher than what is required to completely destroy it? This is the point I'm making, eventually there is an upper limit to the wind required to do the damage, and you can't go any higher than that without further information.

 

And how do you know many of the 2003 F3s would be EF4s today? Are you just making that up, or is there some source out there that confirms this?

 

All I'm arguing is that there was likely no ulterior motive involved here keeping this tornado an EF4. The team did the best job they could with available information.

 

At this point there are far more expert opinions in this thread than I can offer, I'm not going to convince anyone that there wasn't something nefarious or incompetent going on at LZK.

 

[andyhb]

I just picked that span to point out that EF5s aren't necessarily a yearly occurrence. It is possible to have violent tornadoes that do a lot of damage that aren't EF5 in intensity. And plenty of people have mentioned in this thread that recent tornadoes would easily garner an EF5 rating in years past. That to me sounds like people think we're being too conservative now.

 

I'm pretty sure everyone in this discussion realizes that, it's not like we're revisiting the whole Tuscaloosa debate again (and for good reason). I'm also sure that people know that EF5s are not a yearly occurrence. Look at 2010, which had it's share of intense tornadoes but none that I would assume to be EF5 based on the damage. However, there are tornadoes such as Chickasha and Goldsby on 5/24/11, several of the EF4 tornadoes on 4/27/11 and Vilonia now that seem like they would've been rated F5 previously, based on multiple previous cases.

 

Going in the other direction, as I believe someone mentioned, the Rozel tornado last year (also the Pierson, IA EF4 from 10/4 but especially Rozel) did not produce any damage that would indicate EF4 intensity, but then again that gets into the whole radar data fiasco that is scarcely worth going over again for now.

[thewxmann]

Regrading these bolded points, if a home isn't built to withstand high winds how can you rate the winds any higher than what is required to completely destroy it? This is the point I'm making, eventually there is an upper limit to the wind required to do the damage, and you can't go any higher than that without further information.

 

And how do you know many of the 2003 F3s would be EF4s today? Are you just making that up, or is there some source out there that confirms this?

 

All I'm arguing is that there was likely no ulterior motive involved here keeping this tornado an EF4. The team did the best job they could with available information.

 

At this point there are far more expert opinions in this thread than I can offer, I'm not going to convince anyone that there wasn't something nefarious or incompetent going on at LZK.

 

 

No, you have a valid point, I'm just disagreeing with the idea that the ratings under the F-scale were more lenient. That is only true until the late 1990's/early 2000's.

 

Re: 5/4/03. No source that confirms this, just hypothesizing... but many instances of the damage from 5/4/03 are comparable to damage from most EF4's today. 

 

And I agree, there is no ulterior motive for keeping this an EF4... but we do have to acknowledge there is a spatial and temporal inconsistency in the tornado database with regards to what is considered 3, 4, 5 -level damage. This particular tornado has brought that inconsistency once again to light.