Storm Chasing Forum - storms tornadoes and tropical cyclones

Once again referring to Greensburg, it seems the EF-5 rating is being questioned. I won't mention by whom but it could be a due to politics be it funding requirements not sure. It is a shame if this is the case but where does one draw the line given everything is flattened and requires massive government funding to be re-built.

Anyway, what are others' thoughts about the damage they have seen. I never believed I saw any damage that matched EF-5 and was rather shocked when I heard it on the Weather Channel.

Regards,

Jimmy Deguara

I must say Jimmy, when i first saw the damage my feel was EF4 or thereabouts:the town was leveled no question, but i didnt see what you normally characterise to be the truly devastating effects of F5: Debris mainly remained over houses(in an F5 generally all you see are foundations and very small pieces of debris, basically shredded(this is from statements by Fujita, and damage from Tornadoes such as that at Moore)), and were of a larger size that what would be expected. Furthermore on appearances, not all the well constructed houses were destroyed and razed as you would expect from an F5. The wind speed is also more suited to an F4 top of the range.

I too was relatively suprised when i saw the statement of EF5, but didnt question it given the supposedly reputed authorities issuing it. Additionally, many people survived within structures, again not a characteristic youd expect in an F5: generally speaking F5 damage is in conjunction with a number of deaths of people not protected in a shelter, as even the most well constructed houses are blown away.

Some additional notes:
Many trees not stripped and heavily damaged as would be expected.
Cars dont look as mangled or like being thrown for long distances as was seen in Moore Oklahoma and other F5s, rather displaced.
Debris from singular houses often remains over the housing site.
Many brick structures heavily damaged, but not destroyed.
Maximum winds were estimated at 205 mph. This is not consistent with F5 expectations, rather in Fujita's original work this is borderline F4(strictly speaking F3)
Looking further into the EF scale, the damage visible in fact indicates EF3(walls collapse in brick structures) to EF4(brick structures knocked down), rather than the suggested EF5, which would imply brick structures blown away(or translocated).

The pieces of the puzzle dont add up, and while an observational system of tornado strength measurement is used i guess we will never know how powerful the tornado actually was.

Remember that there were very few houses (or lack thereof) in Moore that represented F5 damage. It has been a while since I have looked at the Fujita scale and really have not sat down and looked at the actual 'enhancemements' (ie EF scale), although is it not the case that the most intense damage is considered (whether it is 1 well constructed house or 100)? By all accounts, the magnitude of rotation of the Greensburg storm was at the very top end of the scale -- it was a very, very intense supercell. The actual damage observed in Greensburg? -- I'll leave that to the experts (or local politicians!).

I think the problem here is that the media are only showing the worst damage seen: and if this is the case then I cannot understand how this tornado was rated EF5: there is no trace of well built buildings being blown away, nor even full collapse of brick buildings. While tornadoes can be fickle in their damage paths I severely doubt that EF5 damage would be rated without some clear indications of blown away strong structures to justify the analysis. If the windspeed was only 205mph then I doubt such evidence would be present, and thus I could conclude that monetary factors may have a part to play in the analysis.Clearly if It was an EF5 it was only an isolated vortex within its body and the media hasnt seen the damage assessed justifiying it, as the majority of images from the town skew towards EF4/EF3.

Maybe I'm wrong, but while such rotation and an intense supercell were occuring a tornado formed: and while it may have been a strong tornado, from the wind speed inferred the signature was not fully conductive to the ground it seems. And hence I dont believe it warrants the EF5 rating purely on the basis of windspeed being unlikely to generate sufficient damage.

Hi David,

The damage survey was also done by a reputable engineer who has done other surveys in the past including Moore. Another reputable chaser with sharp eyes for detail also suggests that the damage Moore was a somewhat more intense than in Geensburg. What readings were experienced I cannot suggest. Was it the shear size of the tornado being 1.7 miles wide as compared to half mile wide at Moore would perhaps represent different readings? Not sure.

We happen to see the damage from Moore on Tim Marshall's DVD and it was very intense in terms of the cars being toppled around and crushed. Apparently the reading may have been issued given a car was moved from its location Anyway, we will a little later - this person has to release a paper so it will be interesting professionally what evolves.

Coincidently, I went to an AMS (American Meteorological Society) meeting at Fort Worth NWS, The topic being presented was the new EF scale. The new scale in summary changes the winds speeds represented by the various damage scales. They wanted a better scale representive of the winds - the lower end were too low and the upper end winds were too high. The damage scale itself is the same so it fits with old data. There are other components whereby the steps used to determine the rating can be scrutined or checked to be more consistent but I think the summary above is sufficient for this discussion.

Regards,

Jimmy Deguara

My 2c worth on the deabate about Tornado strength or intesity is this: I haven't seen real finger of God devestation since the infamous Jarrell Tornado., May 27 1997. That torndao actually scoured the ground of grass and it turned a Prime Mover into the most twisted piece of wrecked debri I have ever seen, it also stripped the skin from the carcasses of people and cows. Not to mention though that houses it destroyed were not "well constructed" brick or masonary homes, however it not only tore them completely from the foundations but it completely obliterated the debri leaving in some cases nothing at all! It was definately more savage then moore imo.

Hi Jimmy,

yep I guess it does come down to a final objective assessment of the damage. Obviously there is no meaningul correlation between tornado width and strength - eg Hallam was also EF4. The thing is though, Greenburg is a two-and-a-dog hamlet - I'm not being disrespectful at all, but Moore is a fairly high-density urban area. You cannot compare the two based on apparent damage to vehicles as I would think there would be many more vehicles available as debris in an urban area. The Moore tornado was apparently 1 mile wide near Bridge Creek, just southwest of Moore. This was the other area of F5 damage. Bridge Creek is smaller than Greensburg and I dont recall seeing such obvious carnage as there was in Moore. Yes there were some cars that were twisted wrecks and buildings were completely flatened / debris removed, but in Moore there were twisted wrecks and God knows what else everywhere. So, it all comes back to the actual damage assessments in my oppinion.

yeah Jeff,  Jarrell was huge. Perhaps the somewhat slower movement of the tornado meant that anything in the path really did get dusted up. It is impossible to say whether maximum windspeeds were greater than in Moore/Bridge Creek but I agree, that on the evidence available, it does seem to have obliterated structures like no other tornado has.

Bridge Creek / Moore Tornado ( http://www.srh.noaa.gov/oun/storms/19990503/storma.php#9 )

"Bridge Creek

Two areas of F5 damage were observed in the Bridge Creek area. The first was in the Willow Lake Addition, a rural subdivision of mobile homes and some concrete slab homes in Bridge Creek, in far eastern Grady County. Two homes were completely swept from their concrete slabs, and about one dozen automobiles were carried about ¼ mile. All mobile homes in this area in the direct path of the tornado were obliterated, resulting in a high concentration of fatalities. Asphalt pavement about 1 inch thick was also peeled from a section of rural road EW125. The second area of F5 damage was observed about 1 mile west of the Grady/McClain County line and consisted of a cleanly swept slab home with foundation anchor bolts and another vehicle lofted ¼ mile. The maximum width of damage in Bridge Creek was estimated to be 1 mile. Approximately 200 mobile homes/houses were destroyed, and hundreds of other structures were damaged. The Ridgecrest Baptist Church in Bridge Creek was also destroyed. Twelve people died in Bridge Creek, nine in mobile homes. All fatalities and the majority of injuries were concentrated in the Willow Lake Addition, Southern Hills Addition, and Bridge Creek Estates, which consisted mostly of mobile homes. Compared to sections of Oklahoma and Cleveland Counties, which were also in the path of this tornado, eastern Grady County, including the Bridge Creek area, is rural and sparsely populated.

South Oklahoma City, northeast of Moore

The tornado then continued northeast and entered the southern portion of a sparsely populated industrial district. F4 damage continued through this area to near SE 89th St., the Cleveland/Oklahoma County border. Moving into Oklahoma County, the tornado curved northward, through the remaining industrial district north of Interstate 240, where 2 businesses were destroyed. This damage was rated F4. Two people were also killed at a trucking company near the intersection of S. Bryant Ave. and Interstate 240. A freight car, with an approximate weight of 18 tons, was picked up intermittently and blown ¾ mile across an open field. The body of the freight car was deposited southeast of the intersection of S. Sunnylane Rd. and SE 59th. Gouge marks were observed in the field every 50 to 100 yards, suggesting the freight car had been airborne for at least a short distance. While tornado A9 was moving through southeast Oklahoma City, another tornado (A11) touched down briefly near the intersection of SE 80th and Sooner Rd. (Oklahoma County). Tornado A9 then entered residential neighborhoods between SE 59th and SE 44th, where a woman was killed in her house.

Midwest City and the storm's demise

Tornado A9 then crossed 29th St. into Midwest City (Oklahoma County), destroying 1 building in the Boeing Complex and damaging 2 others. Widespread F3/F4 damage continued as the tornado moved across Interstate 40, affecting a large business district. Approximately 800 vehicles were damaged at Hudiburg Auto Group, located just south of Interstate 40. Hundreds of the vehicles were moved from their original location, and dozens of vehicles were picked up and tossed northward across Interstate 40 into several motels, a distance of approximately 0.2 miles. Numerous motels and other businesses including Hampton Inn, Comfort Inn, Inn Suites, Clarion Inn, Cracker Barrel, and portions of Rose State College, were destroyed. Some of the damage through this area was rated high F4, however low F5 was considered. The tornado then continued into another residential area between SE 15th and Reno Ave., where 3 fatalities occurred. High F4 damage was inflicted to 4 homes in this area. Two of these homes were located between SE 12th and SE 11th, near Buena Vista, and the other 2 homes were located on Will Rogers Rd., just south of SE 15th. Damage then diminished rapidly to F0/F1 as the tornado crossed Reno Ave. The tornado dissipated 3 blocks north of Reno Ave., between Sooner Rd. and Air Depot Blvd.

Summary

The Oklahoma State Department of Health in Oklahoma City recorded 36 direct fatalities. In addition, 5 people died of illness or accident during or shortly after the tornado, and were not considered in the direct fatality total. The number of injuries was estimated at 583, based on numbers provided from the Department of Health, which were then adjusted to account for people assumed to be unaccounted for. Injuries which resulted from removing debris, conducting search and rescue efforts, and taking shelter from the tornado, were not considered in the injury total. An estimated 1,800 homes were destroyed, and 2,500 homes were damaged, resulting in approximately $1 billion in damage."

This is a great picture of the Greensburg tornado for before and after comparison if you haven't all already seen it. I won't make any judgment on the EF rating.
(http://i27.photobucket.com/albums/c172/enak12/Greensburg_KS_Before_and_After.jpg)

The majority of homes damaged/destroyed in Greensburg were built before 1980...the construction was mostly high quality....several homes that were completely destroyed were built before 1930 when hardwood was used for structural framing....I have seen several homes in the past that had been built before 1930 that were "SKINNED" by F-3 damage on the old scale (157-206 mph)but the roof and wall structures remained intact...the parameters for the new EF scale were exceeded in several areas....the quote is "...If any or all of the damage is consistant with EF-5 damage then the entire damage path is considered EF-5 damage"....Just my 2 cents....

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.

Just with respect to well built houses(pre 1980 id assume from the design): images shown of the town shown several of these still intact. I have heard no statement or report mention a particular reason why EF5 was assessed: Whereas for the Moore tornado there was significant evidence in all cases to warrant the damage assessment.

The damage scale should really reflect the wind strengths of the original work by fujita.(By which this tornado was an F4).

I'm not sure how you arrive at this conclusion John - EF5 is not based on what we see from above or in photographs, but through intensive investigation of the damage by structural engineers. There must have been some damage in Greensburg, presumably a clean foundation where a house once stood, in order for that EF5 classification to have been given in the first place. Any subsequent questioning of this must be related to the state of that house prior to the tornado,,,, or something else. In the case of the Moore tornado, there was very little F5 damage either really. That said, perhaps Moore was a more 'violent', violent tornado, it is impossible to say.


Those images above are sobering to say the least.

Well david the fujita scale is derived from the windspeed as a proportion of the mach number in the F-series. Fujita defined the various categories based on the damage caused by a wind speed of that magnitude, as can be seen in the diagram of his work below, and was originally designed to pick up categorising of wind speeds where the beaufort scale left off.

http://www.spc.noaa.gov/efscale/Fujita1002.jpg

As can be seen there were 6 categories divised, which include descriptions(referenced from NWS.noaa.gov)

F0 (Gale) < 73MPH Some damage to chimneys; branches broken off trees; shallow-rooted trees pushed over; sign boards damaged.
F1 (Weak) 73-112MPH Peels surface off roofs; mobile homes pushed off foundations or overturned; moving autos blown off roads.
F2 (Strong)113-157MPH Roofs torn off frame houses; mobile homes demolished; boxcars overturned; large trees snapped or uprooted; light-object missiles generated; cars lifted off ground.
F3 (Severe) 158-206MPH Roofs and some walls torn off well-constructed houses; trains overturned; most trees in forest uprooted; heavy cars lifted off the ground and thrown.
F4 (Devastating)207-260MPH Well-constructed houses leveled; structures with weak foundations blown away some distance; cars thrown and large missiles generated.
F5 (Incredible) 261-318MPH Strong frame houses leveled off foundations and swept away; automobile-sized missiles fly through the air in excess of 100 meters (109 yds); trees debarked; incredible phenomena will occur.

Note that: "Without a thorough engineering analysis of tornado damage in any event, the actual wind speeds needed to cause that damage are unknown" However what is clear is that F5 damage requires significant occurences to occur, which to my knowledge have not at Greensburg.

Hence from damage estimates we know that we likely have a tornado in the order of F4.

Looking to the enhanced Fujita scale, which has upper bound, lower bound and expected analysis of wind speed required to cause certain types of damage to buildings. See the link below.
http://www.spc.noaa.gov/faq/tornado/ef-scale.html
Now to categorise as an EF5 the tornado must have indicators suggesting windspeeds greater than 205 MPH. A look at the common damage seen at the site of the Greensburg tornado for all different sorts of structures reveals  that even if we take the Upper bound value(which is really not a good expectation, the estimate is far better), the maximum estimate of damage visible in the town is of the order of 200MPH. Now with the true value of windspeed being much closer to the estimate it can be seen that the likely windspeed occuring at greensburg was somewhat below the EF5 threshold, and therefore the tornado probably should have been classified EF4.

Another interesting thing ive just noted is the removal of car displacement and asphalt ripping from the wind speed estimates, which I think is a strange move. Additionally the EF scale basically ignores how strong a tornado is after the point is reached when the windspeed becomes sufficient to be lethal to those in well built structures above ground. So hence upper level F3 and F4, F5 all fall into this category.

In Moore i completely disagree. The displacements of the cars and their mangling indicate an extremely intense tornado, and multiple structures were quite literally blown away. Just take a look at the damage in Greensburg to note the difference in tornado strength between the two(if you really want to blow it away look at the damage from Jarrell) Not only this but doppler indicated windspeed indicated a strength near 300MPH, which is more than reflective of and F5.

Hence considering the significance of the event, the Greensburg tornado was likely bumped up to EF5 to ensure adequate funding for the rebuild.

The damage HERE (http://www.srh.noaa.gov/oun/storms/19990503/) at Moore was particulary severe and was classed as F5.

And here is a pic of the Moore tornado.

(http://www.met.utah.edu/jimsteen/ams/quiz/quizpics/q2.jpg)

A quote from Sam Baricklow about the Jarrel F5 Tornado.


Cars were even obliterated in Jarrel. Check out this pic.

(http://www.k5kj.net/jer14.JPG)

Jarrel tornado right before it became a Barrel/Wedge

(http://home.austin.rr.com/candylind/caching/deadmanwalking.jpg)

I think all three are obviously violent tornadoes, no doubt but as for ratings that has to be left for the experts. But I wonder how it compares to Andover in 1991?

What do you mean "we" John? As far as I know a NWS damage assessment rated this tornado as EF5. If there was one single point of EF5 damage then it was EF5. Unless you have been through all the damage with a fine-toothed comb you are drawing a very long bow as to be so confident that is was not. Furthermore, your comparison to Moore is no grounds on which to conclude that this tornado was not EF5 . Accordingly, and based on what Jimmy wrote initially, the question is what/if any factors may have compromised the damage assessment. If this is found to be the case the tornado will no doubt be downgraded. I certainly wont be making the call from my armchair!


Hence from damage estimates we know that we likely have a tornado in the order of F4.

Again no you do not! You have not scrutinised the damage in any detail - you are simply comparing what you see in photos to a likely high end-F5 event in an urban area (Moore). The Moore tornado swallowed up a very large car yard of course there were more mangled cars. Of course there was more debris in the funnel (i would say) to act as a wrecking ball. Nevertheless, this Greensburg storm only had to produce spots of EF5 damage to be given that rating and that seems to be the case for the moment.

When all is said and done the Fujita Scale is a damage assessment scale, not a measure of a tornado's maximum intensity. Now, given that Greensburg is but a few miles north-south and given that this tornado died just north of town it did not have a great opportunity to produce EF5 damage really. You see, this is what interests me -- how intense do these beasts get...what are the limits? I don't care what EF rating is given to this storm in fact I'd rather them all be EF1! But which storm had the more intense circulation and tornado -- both of these storms are of an intensity seldom seen.

That tornado is a beast Jeff - I think you'll find that is how it was as it approached Bridge Creek. The funnel was more slender (lets say a large stovepipe) as it approached Moore.

What amazed me with the Andover tornado was the intensity of rotation - I guess everyone has seen the video on Tornado Video Classics. In fact that might be the tornado where they commented on suction vortices being visible.

I know we are going off topic, but here is some video of the Andover tornado. This always blows me away - check out that rotation...

http://www.youtube.com/watch?v=BAmKvxIEY20

Jarrell - not the best footage  http://www.youtube.com/watch?v=k-K-bj8YhiQ

Oklahoma City -  http://www.youtube.com/watch?v=4pbqGsS5iB4&mode=related&search=

red rock Oklahoma http://www.youtube.com/watch?v=AvMMcmtNUf8

Sorry i didnt clarify this sooner, commonly in scientific work the third person is used instead of the first person. Particularly when im working on all these assignments I mistakenly use scientific 3rd person. Its simply my opinion(and that which im attempting the convince the reader of).

Quote from: David Croan on May 16, 2007, 09:43:20 PM
Furthermore, your comparison to Moore is no grounds on which to conclude that this tornado was not EF5 . Accordingly, and based on what Jimmy wrote initially, the question is what/if any factors may have compromised the damage assessment

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.

My hypothesis is thus(if you didnt gather it from my posts):
Given the damage visible from the Greensburg tornado(as shown in imagery which i will further clarify below), I believe that it is possible that the damage assessment may have been compromised on the premise of being a close to EF5 adjusted upwards for sympathetic or historical reasons. My points are attempting to justify this hypothesis.

Quote from: David Croan on May 16, 2007, 09:43:20 PM
Hence from damage estimates we know that we likely have a tornado in the order of F4.

Again no you do not! You have not scrutinised the damage in any detail - you are simply comparing what you see in photos to a likely high end-F5 event in an urban area (Moore). The Moore tornado swallowed up a very large car yard of course there were more mangled cars. Of course there was more debris in the funnel (i would say) to act as a wrecking ball. Nevertheless, this Greensburg storm only had to produce spots of EF5 damage to be given that rating and that seems to be the case for the moment.

To back up my assertions on this point: I have viewed countless images(im talking hundreds im really interested in this) from Greensburg in order to perform this analysis(which i did using the exact EF scale, as outlined by the NWS), and based on this analysis concluded that we have a high end EF4 event rather than an EF5.(note that I havent posted each image and what it correlates too to save space, and your time, ive actually filled a small notebook with my notes) Now while this may not be the best method of damage assessment via images, it is a darn sight better than just coming out and saying it was EF4. The high end EF4 conclusion is reached by looking at the various buildings and performing a damage analysis(visible) on the structure. From this conclusions can be drawn from data obtained via intensive study in wind-tunnel systems. I am simply saying that the damage visible reflects more than likely a maximum upper bound limit, rather than a good estimate of the tornadoes actual strength. Hence adjusting down slightly I conclude we likely have high end EF4. This is what my analysis was intially performed on.

In addition to this, I thought i would just run a comparison to the Moore F5 event and other events of a similar class(F5's are certainly EF5s). From what the comparison's show it can be seen that:
1. The debris does not appear  to be swept away from the structure it came from, which is unlike the other events(take for instance Andover)
2. The vehicles that do appear in Greenburg are relatively undamaged, thus suggesting they havent been moved far. This again is contrary to what was seen in other events(where we have displacement of near a 1/4mile).

There are probably other points that could be made, however I agree with David that comparison of a Top end F5 event is not prudent for a low end F4(low end EF5 at maximum).

Quote from: David Croan on May 16, 2007, 09:43:20 PM
When all is said and done the Fujita Scale is a damage assessment scale, not a measure of a tornado's maximum intensity.

Just to clarify for you David:
Quoting directly from the SPC: http://www.spc.noaa.gov/efscale/
Dr. T. Theodore Fujita first introduced The Fujita Scale in the SMRP Research Paper, Number 91, published in February 1971 and titled, "Proposed Characterization of Tornadoes and Hurricanes by Area and Intensity". Fujita revealed in the abstract his dreams and intentions of the F-Scale. He wanted something that categorized each tornado by intensity and area.

And from this Fujita found that a way to deduce the maximum observed intensity of a tornado was via a damage assessment of its path.

Quote from: David Croan on May 16, 2007, 09:43:20 PM
Now, given that Greensburg is but a few miles north-south and given that this tornado died just north of town it did not have a great opportunity to produce EF5 damage really. You see, this is what interests me -- how intense do these beasts get...what are the limits? I don't care what EF rating is given to this storm in fact I'd rather them all be EF1! But which storm had the more intense circulation and tornado -- both of these storms are of an intensity seldom seen.

Here I completely agree. Fortunately or Unfortunately(depending on the resident or scientific perspective), the storm went through a cyclic mesocyclone phase just after the town, limiting the evidence available to assess the tornadoes intensity. I too would like to know how intense tornadoes get, and hence why i take such interest in this debate. At this stage I don't believe the movement to EF rating is really reflective of what we want to know about the tornadoes. As you say the rating(which is all the rage) doesnt matter: what would be interesting is to compare the circulation strength of storms to the tornado generated by those storms: and this would particularly be interesting for the high end events. Maybe something like this could constitute a piece of research or thesis I will do in the future, Until then it is an unknown quantity. However I do believe the original Fujita scale is useful to seperate the relative power of events, and hence why if the fujita ratings were still used I would dispute the assessment that such a tornado was F5(which damage suggests it is not).

Hope that straightens things out.


NB:
The images of the Jarrel multiple vortex stage are some of the most amazing images ive ever seen, and id truly like to find out more about how split main vortexes occur, and why it is such a rare occurence. This may sound sad but seeing tornadoes, both big and small has always got me excited and rushing off to find out more, and while i detest when they impact on peoples lives, I truly am constantly amazed by this phenomen of nature.


(sorry John I butchered your post formatting)

I agree that the Moore tornado was very likely a stronger tornado.  I havn't studied the EF scale but maybe the Greensburg tornado gets its 5 rating due to the width of the destruction. 

We passed through Greensburg area yesterday on our way south.  While we weren't permitted to enter the town we did get to the edge of town where EF4 damage started.     

Steven,

The width of the damage path certainly was mentioned as a probable factor towards achieving EF-5 rating.

John, I don't have sufficient time to respond in depth to your points above (by the way please do not try clarifying points that should have been clarified and clearly discuss the topic).

The main aims in developing the EF-scale from the old scale was:

- to provide a scale that is consistent in terms of damage as the old scale

- to provide better estimates of wind strengths - that with better understanding of wind dynamics were proven to show lower ratings has winds too low and upper ratings had winds too high

- to provide more reliable techniques and an array of checks that enhance and hopefully provide more accurate wind estimates within the rating

So really EF-5 and F5 should be the same damage. The main point in discussion here (and hopefully to remain here) was that should funding /politics influence decisions if this was the case. To clarify even further, was the rating reasonable anyway - which is what is being discussed above? Perhaps it was close to EF-5 and pushed over the line for whatever reason?

Regards,

Jimmy Deguara

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.

Bang on David, its good we are starting to talk on the same wavelength.

My assessment comes from the damage photography available, and in this respect I cannot see anything that warrants more than an EF4 rating. However my questioning comes on the back of the photos being provided by the Media, which naturally has a tendency to seek the most destructive or horrifying images in order to control the press. Hence if there are no images indicating EF5 damage: the question is where is the EF5 damage? The media would naturally gravitate to the most damage they could possibly find, thus likely providing an image of it.

The impressiveness of the damage does not sway my opinion of the comparison: what I was arguing was that since EF5 supposedly encapsulates F5 tornadoes: shouldnt we see comparable aspects within the damage path or are we just using a flawed system, which will never reflect the tornado intensity properly.
That particular comparison is not as strong as the actual damage evidence ill be the first to degree, although it should be considered.

From the imagery available showing the rotation of Greenburg, you are right in your conclusion that it was clearly one of the most intense mesocyclones in the period of the technologies use. On the poor meteorological pun I must say this: while we cannot tell which had the more intense rotational velocity at the mesocyclonic level, what is evident from the damage is that Moore likely had a far more intense rotation at ground level as compared to Greensburg. This raises the question that with GrLevel3 data are we able to directly correlate mesocyclonic rotation to rotational speed within the tornado itself? Or is their a loss between the two systems which is unpredictable resulting in fluctuant tornado maximum velocities for certain mesocyclone intensities.

Just reading back through that: I apologise for the use of grossly technical terms outside of the Advanced Meteorological discussion.

I must say David, im enjoying this debate kinda reminds me of arguments in "The Meaning of Life" 

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.



Mike

I think you missed altogether the point of this debate mike: we are considering it on the basis of difference in funding.

Greensburg was not 95% destroyed: rather 95% damaged, large portion beyond repair. There is a significant difference: additionally you will note that only the local official made that comment, which is part of why this debate arises: were there vested interests within the damage assessment? Clearly that town official is to benefit if people consider his town that worse off that it needs even more funding to repair.

The point of Greensburgs water tower being destroyed raises an interesting question:
An object being heavy does not matter, water towers while heavy have relatively weak support structures, together with large surface areas and a height within the maximum windspeed range, hence more than likely they will be damaged or destroyed.


We are not contesting that this was a very powerful storm that did vast damage: what we are contesting is a blurring of the rating guidelines in order to secure more disaster relief(which if you think about it is fraud).

While I agree that we are only using an arbitrary scale I dont believe it is prudent to ignore it: by categorising we can use storm dynamics in order to better predict the strength of tornadoes they produce: There is method to the madness

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!

Mike

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)!

Ive gotta say, such a concept scares me immensely. This tornado was big enough, and yet the damage swathe of the next appears even larger: What interests me is what within storms causes these giant variations within the wind swathe of a produced tornado? What causes a storm to produce a massive tornado with wind that has been experienced in a much tighter vortex?

Additionally I think that Greensburg can consider itself fortunate that the formation of the second tornado did not occur over the town while the first was still in progress. 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.

I have also found a site which has some damage that may reflect this EF5 rating, although i dont agree with this chaser plunging into disaster zones in order to obtain footage to sell, I feel that the images obtained are very interesting with looking at what this tornado did.

http://www.ultimatechase.com/chase_accounts/Greensburg_Tornado_Damage_Survey.htm

Images 2, 9, 11, 20,35 Show seriously translocated(and smashed) cars, which would be expected with a original F4-F5 event.
Images 15,17,19,26,32,38 Show homes and buildings with pretty much nothing left standing, and some with exposed slabs, one of these images is part of what i suspect may be part of the EF5 identified swathe(have a guess which one and it may not be obvious without looking at EF scale). 

While I in no way condone those who take pictures of damage for selling reasons, I believe that such information is highly useful in assessing events such as these.

These are truly frightening creatures of natures creation, and should be treated with all due respect(not like those idiots who got in really close to the tornado pre-greensburg(they have done the same for Hurricane Katrina)).

John,


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.

(http://www.crh.noaa.gov/Image/ddc/GreensburgTornado/Kiowa%20county.gif) 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.

Regards,

Jimmy Deguara

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!

Mike

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.

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.

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!

Mike

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

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

Not my implication Jimmy, what I was meaning was that the second larger wedge was quite likely stronger than the first, however fortunately it did not encounter other towns before it weakened(and another tornado formed, from the look of it its cyclic mesocyclone formation).

The damage swathes of these two tornadoes are immense and amazing, If indeed the first funnel lifted and moved to amalgamate with the second, It is indeed likely that the second tornado was far more powerful than the first.

I guess this all comes back to the respect for severe weather: really this is a terribly frightening situation, incredibly powerful tornadoes moving through towns in the dark, and we as chasers must understand these dangers, and use the images and knowledge we find to help better protect those in the line of danger. Really seeing images such as insane tornado chase videos are all very well, but it misleads the public into believing that they are safe, only to have an event such as Greensburg come along.

Maybe a poorly constructed train of thought, but it gets what i mean across: I blame sleep deprivation due to assignments.

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!

Mike

Just to add to Mike's final point there are actually over 1600 tornadoes in the United states each year(reported not sure if all confirmed, particularly for F0s damage assessment sometimes not done).

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! :)

Mike

Hi,

Just in connection with this discussion, I have pictures of Greesnburg taken during our brief survey  (http://www.australiasevereweather.com/forum/index.php?topic=443.msg3367#msg3367) at the following link:

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

Regards,

Jimmy Deguara

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?

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

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 

Hi David Carroll,


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

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

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:


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

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

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

David,

Fair enough - thanks for elaborating.

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

Regards,

Jimmy Deguara

The EF scale actually takes note of the type of building/structure, not just the damage done to that building. It actually disregards windspeeds somewhat, with EF5 being anything over 200 mph: hence leading to little definitive difference between something like Jarrell or White deer and something like greensburg(which as Jimmy has eluded to is questionable, although i doubt we will know for certain).

 :)  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

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.

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.

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 :)

Since when do we speak foreign tongues here? Im confused LOL. As far as i can tell David has gone to French, and Mike looks like hes writing latin: but i may be wrong.

David,
as suggested and allayed with evidence above I think we concluded that rating this tornado an F5 was rather inappropriate given the assessment of the damage. However when using the new rating system(which i am not overly supportive of from a research perspective) an EF5 damage swathe was quite likely present in some part of the field, although as outlined by Jimmy this could be attributable to debris projectiles due to the large radii of the strong winds. Either way, it has been rated an EF5(possibly for publicity but who knows), and we still do not enough about tornadoes and tornadic behaviour to question that assertion(even by comparing damage assessment). In my view on the old scale it would barely rate F4, but thats my considered opinion.
 
Edit: Spelling

Hi John,


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

Fair enough Jimmy, I will elaborate:

By my conclusion on the EF scale I see no damage present to suggest an EF5(with its associated structure damage), however I realise that without actually being officially on site this is hard to confirm. From what I have seen and evaluated using the damage scale the highest possible damage i can see suggests High EF4.

Reasons for my feeling on the Fujita Scale:
1. These are the respective definitions from NOAA for the F scale:

F3: 158-206mph : Severe damage. Roofs and some walls torn off well-constructed houses; trains overturned; most trees in forest uprooted; heavy cars lifted off the ground and thrown. Example Here: notice similarity to much of greensburg, also you see some of the damage criteria apparently being met.
http://www.spc.noaa.gov/faq/tornado/f3.htm

F4: 207-260mph :Devastating damage. Well-constructed houses leveled; structures with weak foundations blown away some distance; cars thrown and large missiles generated. Within the damage images ive seen I feel that this category reflects the maximum extent of what happened at Greensburg.
http://www.spc.noaa.gov/faq/tornado/f4.htm

F5 261-318 :Incredible damage. Strong frame houses leveled off foundations and swept away; automobile-sized missiles fly through the air in excess of 100 meters (109 yds); trees debarked; incredible phenomena will occur.To me it is clear that this isnt apparent at Greensburg.

2. Even using the enhanced Fujita Scale there is no evidence to suggest windspeeds that reflect a rating above F4. However I do know that the FScale windspeeds are not to be taken for gospel as they are unverified(mind you the same can be said somewhat for the EF scale). No damage criteria are met to raise the windspeed above 210 mph, hence also suggesting low end F4 by Fujitas original work. I dont believe this is as conclusive as point 1, although it is true IFF the winspeeds on the Fscale are ballpark.

From these definitions and what i assessed from photos using enhanced fujita I can only conclude that at most this tornado would have rated an F4 on the orginal scale.

If anyone would like to see my full assessment notes I could organise to post them once i begin Uni holidays.

I hope this answers you questions Jimmy,
John.

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.


Any comments here?

Regards,

Jimmy Deguara

Definitely not Jimmy: there is not that much consistency in the damage scaling noted: Jarrel wouldve been rated an EF5 and but for imagery of the event people would liken it to greensburg purely on the basis of that statement: as you have referred to apriory the damage between these two events is not consistent. There is no real analysis if the tornado is above the EF5 threshold: it just becomes an EF5. I believe this is a serious flaw and non reflective of actual damage. While the more detailed analysis of behaviour under wind speeds is very useful it has limitations: certain towns may not always have those structures and thus the damage could be underrated.

 Sorry i missed that remark Brad. If you look at the area surrounding the road in that particular image you can see a dark brown scaring around a black surface: this is consistent with other images i have seen of intial asphalt ripping(it works its way from the edges). Unlike other strong events this one did not appear to do as much ripping, but this is a feature noted with very powerful tornadoes(F4+) such as those mentioned earlier in the thread. It is my opinion that this could have been the location for the EF5 rating near to this point as if this is an area of highest windspeeds there is likely a continuation of that swathe through houses. This would be where i wouldve looked for damage in order to find the worst of it. That was the basis of what i was saying.

Hope that clarifies.

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.

This thread I think now is becoming clogged with various opinions and in some cases conflicting information that for any reader may become confusing - I guess it could then detract from the original topic and the original debate.

Thanks for all the worthy discussion - I think I will have this closed with perhaps permission from any member with anything new updated information related to the topic such as links to reports etc to be posted by the moderators.

Regards,

Jimmy Deguara