Author Topic: Greensburg Tornado - EF4 or EF5 - How Savage Was It In Real Terms?  (Read 70737 times)

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Offline David C

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RE: Greensburg Tornado - EF4 or EF5 - How Savage Was It In Real Terms?
« Reply #15 on: 19 May 2007, 07:59:05 AM »


I request that you back up your assertion that a a comparison to a supposedly similar strength(EF5) tornado is not valid? In my view while all tornadoes are different, it is likely that they contain consistent elements with respect to damage elements, hence on this point I justify my comparison with Moore.


Hi John - good post! We may be talking a slightly different language here. IMO, a comparison based on photos as available on the web - which is all we can do here is not valid for discerning tornado intensity. You commented yourself that Jarrell damage was on a different level. My point exactly - one cannot use photographic evidence of Jarrell as a standard by which to compare all other EF5 tornadoes.  I have never suggested that Greenburg (or Moore) was the more intense tornado - simply whether or not Greensburg is EF5 or EF4. One EF5 tornado might clear the foundation of a complete row of houses (or whatever the criteria are with the new scale). Another EF5 might only clear the foundation of one house. The foundation of at least one house must have been swept clean in Greensburg for that rating to have been given (it seems you cannot find evidence of Ef5 damage from the web, hence your reason for EF4!). This is irrespective of whether Moore drilled a hole 1 mile deep into the ground and struck oil! Both are still EF5 despite photographic evidence suggesting one being more intense than the other based on the 'impressiveness' of damage. Do you understand my point?

From the evidence I have seen, Greensburg has set the upper limits of low-level mesocyclone intensity in recent years. This was a cyclic storm and different to Moore which was in a remarkably steady state by all accounts. We did not have all the GrLevel3 data around in 1999 either so we cannot say which storm had the 'Moore' intense rotational velocity (sorry, could not help myself). It would have been fantastic if a DoW was taking measurements of the Kansas tornadoes to compare with the 319mph  +/- velocities recorded in Moore.
« Last Edit: 19 May 2007, 08:16:16 AM by David Croan »
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Offline Mike

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RE: Greensburg Tornado - EF4 or EF5 - How Savage Was It In Real Terms?
« Reply #16 on: 22 May 2007, 09:06:31 AM »
Here's my 3 cents worth.

Does it really matter how close this tornado was to EF5 scale?  In reality when i look at Greensburg which was 95% flattened, I don't really care if it was 3mph short of an EF5 'damage' scale.  What constitutes an EF5 event that satisfies everyone?  The town ground down to dirt?  There were cars wrecked and flung around, there were structures that were obliterated that were'nt in the 'ground zero' section of the funnel.

There are reported cases of F0 tornadoes having the same damage path as an F4 purely on the assessment of the engineers who viewed the damage scenes and reports on F4 wedges having the comparible damage to an F2.   Just because there were not particular items that were obliterated in relation to damage to Moore, Jarrell what does that matter?  This storm was very vicious in its structure as we've seen also that it produced so many tornadoes from one storm system proved that. (even another EF2 was sighted heading for the town but lifted after the EF5 went through Greensburg!)

It must be remembered that the perameters set by these scientists for the F scale or the new EF damage scale have not been proven scientficially at all.  The margins they use are 'a guide' to damage assessment dependant on what structures are destroyed.  Does a trailer park obliterated off the face of the planet and vegetation stripped constitute and EF4 even though sightings of the funnel were of a marginally wide stove pipe for example?.

From the city before and after satellite pics would you rate the damage as high EF4 or low EF5?  Jeepers, the wind perameters for both are negotiable.  Surely it really doesn't matter only perhaps for the record books - but doesn't 95% of the observers say it was an EF5?  Don't the scientific results, observations from the NWS agree on the wind profiles etcetera?

How can we ever determine EF5 damage if we dissect how many leaves were left on a tree or how many vehicles resemble rubbish bins?  Greensburg's water tower was totally destroyed and that thing is not a small, light landmark!!!

For my 3 cents if the thing was 3mph slower in wind speed to rate an EF5 so what.  Those damage ratings are variable - that's why they restructured the Fujita scale and no doubt will do so again with the EF version.  Otherwise they would not have adjusted it at all if those perameters were gospell.



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Offline Mike

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RE: Greensburg Tornado - EF4 or EF5 - How Savage Was It In Real Terms?
« Reply #17 on: 22 May 2007, 10:35:56 AM »
So sorry if i misread some parts, was not stepping on toes at all!  I see now.  Well in that case there definitely is a course for comment!

I did not know that there was a 'case' for more funding.  I would have presumed that whatever relief would come it would be 'across the board' given the damage.  (destroyed or damaged - if my home was wiped of it's foundations I'd call that destroyed and 'beyond repair' really is not 'damaged' is it.  'Damage' really is a bit ambiguous when your lounge room is next door!)

Why or who on earth in the USA is quibbling about how much it takes to rebuild the poor town?  Oh dear, i can see this is going to be another South Carolina without even to this day the government doing what it should to get the place cleaned up.

I take it all onboard and have nothing else to say!  You'll forgive me as I know nothing about the claim for extra funding - more to my fault guys sorry!

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Offline David C

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RE: Greensburg Tornado - EF4 or EF5 - How Savage Was It In Real Terms?
« Reply #18 on: 23 May 2007, 08:48:14 AM »
Bang on David, its good we are starting to talk on the same wavelength.

Yep John, it's clear that there were probably only a few spots of EF5 damage in Greensburg (ie based on the damage assessment that resulted in the rating). I'd say there must be some uncertainty with respect to those spots of damage and this has resulted in some questioning the initial rating. Obviously we are dealing with a spectrum of events - this tornado would probably be at the low-end EF5 (or EF4 depending on how flawed the assessment was). All this notwithstanding, boy, what a scary storm - some are suggesting the tornado that developed north of town was possibly more massive (as in width)!
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Offline Jimmy Deguara

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RE: Greensburg Tornado - EF4 or EF5 - How Savage Was It In Real Terms?
« Reply #19 on: 23 May 2007, 06:30:57 PM »
John,

Quote
Given the country the other tornado moved over I would not be surprised if the vortex was of a similar strength, but did not have a chance to do damage like that of Greensburg, and by the time it did the storm had weakened somewhat.

Although these are possibly the two main tornadoes it produced of such massive size, please do not think it had weakened. I think to produce two massive wedges is a thing in itself. The storm went on to produce multiple touchdowns with significant tornadoes possibly over a few hours based on its warnings though I will await the final assessment. Definitely by midnight, the storm was a stock standard tornado producer with not so extreme velocities.

I agree with David the second tornado produced a wider path.

Please note these are county based assessment ie Kiowa County. Other assessments may be made by separate NWS offices or other teams.

Another interesting point made by analyses of radar is that the Greensburg tornado may have veered and come back into the eastern side of town and then merged with the second violent tornado.

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Offline Mike

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RE: Greensburg Tornado - EF4 or EF5 - How Savage Was It In Real Terms?
« Reply #20 on: 24 May 2007, 07:20:10 AM »
Thanks for the link to those photos John.  They are truly amazing photos - regardless of them being sold to the public or whatever - i agree that they are immensly useful in assessing damage.  I particularly liked the one with the young girl on the swing amongst the carnage - innocence in the face of diversity.  Wonderful stuff.

If the difference between EF4 and EF5 damage is a few extra branches snapped off then from viewing those photos really justifies whatever relief funds are needed.  I've never seen anything like it - thankfully and surely these images must lay to rest that this tornado was just inexplicably monstrous whatever the argument is about relief funding - I just can't see the point in it looking at the damage!

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RE: Greensburg Tornado - EF4 or EF5 - How Savage Was It In Real Terms?
« Reply #21 on: 24 May 2007, 08:21:40 AM »
A friend of mine, who was riding with Jimmy on the night of this tornado, suggested to me that this tornado changed his whole view on storm chasing. Now, talking deliberately around Jimmy, since he would have his own perspective given that these guys saw the tornado,   he described seeing the massive tornado (relying on lightning illumination, remember) and, soon after on approach to Greensburg, he described the intense pungent smell of gas, the continual moan of sirens (as in emergency vehicles not tornado sirens), damage, and a overwhelming sense of catastrophe on a scale which he had never experienced (and few people would experience). It was very fortunate that the second massive tornado did not hit any major towns.

Anyway, w/r to the tornado track above, note the 2nd major tornado very rapidly becoming VERY large - what a dangerous situation for spotters or reckless and / or inexperienced storm chasers. I would not want to be close to that first tornado, but if you were east of town you would have been in for a nasty shock as tornado 1 slid by northwards and a few miles to your west.

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RE: Greensburg Tornado - EF4 or EF5 - How Savage Was It In Real Terms?
« Reply #22 on: 24 May 2007, 08:33:21 AM »
Also on the map, you can note the tornado track curling back to the left during its weakening and final demise, indicative of the mesocyclone occlusion (Also obvious on May 12, 2004 Jimmy - gosh I feel like I am liivng in the past after looking at tomorrow's convective outlook haha). Also, note how the 2nd tornado track assumes more of a path towards the right while growing very wide, possibly reflecting a further right deviation in the track of the mesocyclone (right move) as it became more and more intense and the vertical pressure pertubation was enhanced. No doubt, the mesocyclone was exceptionally intense during this second tornado.
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RE: Greensburg Tornado - EF4 or EF5 - How Savage Was It In Real Terms?
« Reply #23 on: 24 May 2007, 09:43:29 AM »
My meteorologist chaser friend who lives in Oklahoma said to me that this tornado was the most awe inspiring yet most shocking thing he had seen in 6 years of chasing tornadoes.  He had never, ever seen anything so ruthless - even from the Moore OK outbreak - the meso and speed of rotation was just unearthly.  These events apparently coincide with the La Ninya every 10 years or so with uncanny regularity.  Almost all of the outbreaks have had similar weather patterns and just as many supercells spawning multiple tornadoes.  Truly why we are so interested in severe weather.  So many questions and not enough answers from Mother Nature!

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RE: Greensburg Tornado - EF4 or EF5 - How Savage Was It In Real Terms?
« Reply #24 on: 26 May 2007, 09:11:12 AM »
Here's a photo of the Jarrell tornado just prior to it absolutely destroying the Double Creek housing sub-division near Jarrell  http://www.nationalgeographic.com/ngm/9807/popup7.html
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RE: Greensburg Tornado - EF4 or EF5 - How Savage Was It In Real Terms?
« Reply #25 on: 26 May 2007, 12:07:11 PM »
Love the shot, David.  I've done some research on the thing but never really saw a decent photo of it.  I have a fellow workmate from western Texas.  We were talking about tornadoes and he mentioned the Jarrell tornado.  He was living close to the town during that time.  His recollections of seeing the thing had a fairly negative impact on him psychologically.  He's seen his factory wall peeled off like a sardine can from an F2 and seeing the Jarrell tornado still has an affect on him. He steers clear of any large hailstone producing supercells because he's fully aware that there may be a tornado around at any time.

I think every one including the meteorologists at the NWS are grateful also to the chasers that film and give reports - it's this kind of gratitude that makes what we do even more important to the whole spectrum of storm observation.

Mike
« Last Edit: 01 June 2007, 06:31:59 AM by Jimmy Deguara »
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RE: Greensburg Tornado - EF4 or EF5 - How Savage Was It In Real Terms?
« Reply #26 on: 27 May 2007, 07:43:53 AM »
Such good posts.  Sometimes we get complacent about severe weather and as most of us do at times when there's not much intense events happening here or abroad.  When they do happen it really gets the minds clicking over and reflecting back on past events and comparing them.

It proves beyond a doubt that these significant storms are just so complex and not always 'text book' after all.  Sure they have all the characteristics etc, but as they have proved these supercells are a scientists/meteorologists dream when they happen.  So much information gathered from start to finish and added to that the storm reports from chasers doing the right thing and takng notes of specific things about the tornadoes, rotation, structure and the like.

Fortunately technology makes it easier, but there's nothing like the human element to document footage so that the experts can review and enhance everyone's knowledge.

Who knows, they might even reclassify these 'rare' supercells to another level because of the information.  Instead of your classic, LP and HP they might even prefix it something else!

Never ceases to amaze me that even the experts say that tornadoes are 'rare' with supercells - which is true to some extent as not all produce them - but having over 200+ in most seasons makes you wonder if they're not that rare at all!

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RE: Greensburg Tornado - EF4 or EF5 - How Savage Was It In Real Terms?
« Reply #27 on: 28 May 2007, 09:31:25 AM »
Yes sorry, John.  I meant 'localised' tornadoes in one particular area.  I understand there's that many just about every year.  My train of thought was on the spate of current events.  My fault! :)

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Offline Jimmy Deguara

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RE: Greensburg Tornado - EF4 or EF5 - How Savage Was It In Real Terms?
« Reply #28 on: 28 May 2007, 10:36:29 AM »
Hi,

Just in connection with this discussion, I have pictures of Greesnburg taken during our brief survey at the following link:

http://www.australiasevereweather.com/forum/index.php?topic=443.msg3367#msg3367

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RE: Greensburg Tornado - EF4 or EF5 - How Savage Was It In Real Terms?
« Reply #29 on: 01 June 2007, 06:48:14 AM »
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.


Hi John, just in relation to your comment about possible asphalt ripped up - what draws you to that possibility?  Is it just the darkened colouration in the image at that location?  I must say I spent 2hrs slowly driving most of the streets in Greensburg (yes I was Jimmy's chaffeur for the day) and saw no asphalt damage.  Just curious to know if you have heard more?
hmmm June 2nd......