Topic: Greensburg Tornado - EF4 or EF5 - How Savage Was It In Real Terms?

[David Carroll]

Hey all,

Well done on the great photos for Greensburg and other Tornadoes.  I was also in USA chasing from May 12th until May 19th, unfortunately it was the week where not many storms formed, let alone Tornadoes.

One of our drivers John took these amazing photos the week after our tour,
http://www.nc911.com/Misc-Photos/storm_chasing_2007_greenburg,ks.htm, one of their guides was a TV Media Reporter, they were allowed into Greensburg for photos.  What a devastating site to see, to see these photos, really shows the enormous power a EF4 or EF5 does have.  From the people I have talked to in relation to this, I do believe its a EF5.  During our chase, saw many towns affected by many other smaller EF3 Tornadoes, even these caused magnificent damage to structures. 

Greensburg, nothing left to salvage.   http://www.kansas.com/626/  Here are some other photos and reports of Greensburg. 

I look forward to seeing Greensburg rebuilt in the near future. 

Thanks
David

[Mike]

Certainly some thought provoking images David.  The raccoon also got my attention!  The great thing about towns like these after major disasters is that they pull together and become even stronger community wise.  Adversity brings out the best in people, especially terrible destruction such as what they encountered.

It will be most interesting to read all the conference/data reports of this event in the months ahead that the NWS, NOAA and experts alike will be compiling.  EF5's are rare and systems like these are rarer. 

I for one will be enthralled by the results and reports when they come out.  thanks for posting the pics, certainly gives a scope to the damage.

Mike 

[Jimmy Deguara]

Hi David Carroll,

...What a devastating site to see, to see these photos, really shows the enormous power a EF4 or EF5 does have.  From the people I have talked to in relation to this, I do believe its a EF5.  During our chase, saw many towns affected by many other smaller EF3 Tornadoes, even these caused magnificent damage to structures.... 

Although I respect your point of view, the statement above if I understand it correctly seems almost contradictory. Also please tell us who you talked to about this that made you arrive at this conculsion. Further, you supply images from the media person - which of these perhaps convince you of EF-5 damage?

The EF-5 rating was derived using 3 points of damage within the town. One of these points that still remained was also used by another experienced assessor of damage and this person only sees EF-4 damage from the same assessment. For each point that makes me suggest an EF-5 damage factor, I saw other adjacent damage that makes me rethink lower.

Another thought crossed my mind: could the massive amount of debri carried with the tornado being so large have created 'impact' of incredible damage suggestive of higher damage usually associated with EF-5 when perhaps there may have been EF-4 damage/wind scale?

Getting back to the damage of power poles - most were leaning over but not snapped - even within the town. In the tornado that hit White Deer 29th May 2001, all power poles were snapped bar 1. Of course one can correctly argue the strength of the poles but really would not an EF-5 rated tornado have snapped power poles?

I guess I am not an expert but the damage simply did not add to what I had percieved to be EF-5 rating from descriptions such as those in May 3 1999 and Jarrell, Texas in 1997. What David Croan may be saying that there may have been multivorticies that could have created regions of locally EF-5 'maximum rating' (please correct me of I am wrong in my assumption David).

Regardless of the arguments in this debate, the damage is of mass scale I personally had not observed.

Regards,

Jimmy Deguara

[Mike]

I think re the damage is something no-one can strike out as cut and dry.  There are so many factors that scientists and meteorologists do not not know about wind factors in and around these storms simply because assessing damage from tornadoes has not been proven as 'a matter of fact' - it's all theoretical based on wind, debris, structures and the like.  Smaller EF2 tornadoes have been 'assessed' as having EF4 damage simply because of the structures it has hit in its path and likewise EF4 tornadoes have done damage similar to lower rated tornadoes.

I think David was just expressing the view that from what he's seen and likewise yourself Jimmy, that we're not experts and even the experts rated it as high EF4 or low EF5 (if there is such a thing!).

I did not read his comments as contradictory at all - he mentioned either EF4 or 5, that's not contradictory, that's a viewpoint of what he has seen personally. 

It gets back to the same question of relevance, is it EF4 or 5 damage - nobody knows, that's why the scale is set the way it is, it covers a range between these two.  You answered his comment when you mentioned the amount of debris carried by the tornado may have caused EF5 damage - that may well be the case - if the tornado was on the ground for so long who knows what carnage was arond the vortex area - it would be agreeable to say that the more debris in the area most likely would have caused considerably more damage.

You could ask all the residents of Greensburg what they thought and you'd get mixed answers.  Truth is we'll have to wait and see what the reports say on the event, but it's important to understand that just because residents say it was EF5 or other experts say EF5 or EF4 is irrelevant so far because no-one has the answer.

Mike

[Jimmy Deguara]

Mike,

Rather than get off topic, read carefully what I have suggested as being 'almost' contradictory and don't assume what comments I am referring in his statement:

From the people I have talked to in relation to this, I do believe its a EF5.  During our chase, saw many towns affected by many other smaller EF3 Tornadoes, even these caused magnificent damage to structures....

Further, Mike I think you will find that scientists have developed this lastest Enhanced Fujita Scale it being far more thorough. Mike in your generalised assessment of my post, you incorrectly quoted what I was alerting to. So perhaps if I was not clear, I will perhaps elaborate on my question: is it possible that the amount of debri carried around may have caused EF-5 damage despite perhaps the wind strengths causing EF-4 damage?

I await comments from David...

Regards,

Jimmy Deguara

[David Carroll]

Jimmy,  

Im far from an expert in relation to others on this forum. Mike is correct, i was mainly providing my opinion just on many other experts I have talked with.  I have to say, they also have their opinion on whether it was a EF4 or EF5.  This has opened my eyes to what one can expect when chasing storms of this magnitude.  

The photos provided were of a driver also a photographer, not from a media person.  John sent me these photos after the interest I showed, considering we never got to visit Greensburg.  

Its just such a shame so many people had to lose their lives.  

http://www.spc.noaa.gov/climo/reports/070504_rpts.html - This report says it all.  

Dave

[Mike]

The new EF scale just expands the wind speed perametres from the old one.  And as David said it's just an opinion of what 'he saw' - not what he believes whole heartedly without expert qualifications to which none of us have in this determining this damage.   

Mike

[Jimmy Deguara]

David,

Fair enough - thanks for elaborating.

Mike said..

The new EF scale just expands the wind speed perametres from the old one.

Mike, this is only one of the enhancements: there are others that may have been mentioned earlier.

Regards,

Jimmy Deguara

[Mike]

   Healthy discusssion and debate is what it's all about!

The EF scale does use 'wind speed' as set out by met people and wind engineers as they condensed the gusts somewhat and yes, have used the following also to compliment the scale.

 The EF scale still is a set of wind estimates (not measurements) based on damage.  It uses three second gusts estimated at the point of damage based on a judgement of 8 levels of damage to the 28 indicator list.  The 3 second gust is not the same wind as in the standard surface observation.  Standard measurements are taken by weather stations in open exposures using a directly measured one minute speed.

Reports were of wind speeds of 205mph which would rate it EF5, but what rating would they give it if it hit the same place last year? They would have rated it an F3 or F4 depending on the fastest 1/4 mile speed or the 3 second gust!

Mike

[David C]

Reports were of wind speeds of 205mph which would rate it EF5, but what rating would they give it if it hit the same place last year? They would have rated it an F3 or F4 depending on the fastest 1/4 mile speed or the 3 second gust!

Mike

Are you sure about that Mike?

The important thing here is that the emphasis is on damage, not wind strength. The 'windspeed' is simply an inference based on damage. They would have rated Greensburg v2006 based on a damage assessment, from which an F rating would be assigned ( I would say F5 based on cleared foundation subject to this thread's raison de etre). From the F rating, one could infer wind speeds  according to the F-scale only. As it is, it was rated EF5, implying wind speeds greater than 200mph under the EF scale, but that's all. You cannot used wind speeds inferred by an EF rating to slot it into the F scale to determine an F rating.

[David C]

I guess I am not an expert but the damage simply did not add to what I had percieved to be EF-5 rating from descriptions such as those in May 3 1999 and Jarrell, Texas in 1997. What David Croan may be saying that there may have been multivorticies that could have created regions of locally EF-5 'maximum rating' (please correct me of I am wrong in my assumption David).

Hi Jimmy. Yes, suction vortices are one possibility for areas of locally enhanced damage. The EF (or F) scale does not consider how widespread the damage is in assigning an rating, but simply whether or not such damage exists and is attributable to the tornado. It does appear that, as far as Greensburg goes, the damage was not as 'complete' as Moore -- I know this is based on the opinions of damage assessors that you are in contact with who have observed both damage tracks. That's fairly compelling evidence I think. Nonetheless, this was a big tornado and will go down in history as the first EF5.

[Mike]

Oops, sorry David forgot the 'E' in front of the latter part of my reply referring to 'F' ratings - my mistake, so your last part of sentence won't refer to that Allengans contraria non est audiendus   Back at you!

I'm content with the views anyway posted here.  I wasn't trying to add inferences to the F rating as I know it's not to be used now - and I'm aware that damage for EF4 and higher are rated on damage to well well-built constructions that are destroyed - but this argument will go on forever without a definitive answer.  We can speculate, assess and conclude but in the end nobody knows how powerful these things are and that's why the science continues.

Mike

[Jimmy Deguara]

Hi John,

In my view on the old scale it would barely rate F4, but thats my considered opinion.

Can you elaborate on this comment? So what does it rate in your books on the EF scale? Sorry to cover old territory but this quote puzzles me somewhat.

David, yes I am thinking of the sub-vorticies as perhaps some explanation of possible more intense damage locally. What are your comments regarding the possiblility of large masses of debri being carried around creating perhaps more damage as it may seem? I note on a documentary - take what one wants from it but known research experts were commenting about the possibility that the 1997 Jarrell accummulating appreciative volumes of dust and debri causing perhaps more intense damage than one would have anticipated. I realise this is only a generalised depiction of thsie statements but it is food for thought.

Regards,

Jimmy Deguara

[Jimmy Deguara]

Hi John,

No what I am inferring is that I thought that the new EF scale keeps the damage consistent between both scales and adjusts the winds based on current knowledge.

Also, I note Brad had asked for further explanations and also you had drawn attention to ripped asphalt - thence possible EF-5.

In reference to the image posted by enak: i would very much like to see an image of the roadway two streets to the left of the main N-S street. It looks quite possible at that location that we have asphalt ripped up(at least partially) and if that is the case It would be there that i would be looking for some tracer of EF5 damage.

Any comments here?

Regards,

Jimmy Deguara

[Mike]

Yes, It's Latin in both.  Thought he was trying to out-gun me.



The Jarrell rating was F5.

 Is John saying that they wouldn't have or would have rated it F5 if it was not for the photographic/public evidence that came from Greensburg? ( per John's sentence -: Jarrel wouldve been rated an EF5 and but for imagery of the event people would liken it to greensburg

They're not going to reclassify events pre-2007 to the new Ef scale,they've already rated Jarrell.



  Does anyone have info on re this: Jarrell's F5 tornado at its beginning caused crop dirt to be ripped out to a depth of 50cm (20 in), so was there evidence of anything similar in Greensburg?

Edit: 8 in changed to 20 in

What the governing authorities have to clarify is how far does 'Devastating damage' for EF4 and 'Incredible damage' for EF5 go in order to define each? From what I've seen from Jarrell and Greensburg photos there's not a lot to question re extent of damage.  By reading both the table of contents that cover EF4 and EF5 effects - just about everything (damage wise) that happened in Jarrell was mirrored in Greensburg.

Mike

With the wind being gauged at 205 for Greensburg it's an EF4 - but like we've all said all the way through the thread - there are areas which sustained damage caused by debris that reflected EF5 scale characteristics.  We can only go by what the authorities tell us and take it as face value.