Talk:Fujita scale

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Moved comment by Pakaran

Only one web source has a kilometer speed for F6 tornados, which it gives as 513-612 km/h; this does not mesh with Wikipedia's ranges, possibly because one of the sites used a conversion factor with a rounding error.

The proper speed for F6 tornadoes, from Thomas P. Grazulis "Significant Tornadoes: 1680-1991", p. 141, is 319-379 mph, which converts to 513-610 km/h. 511 km/h rounds up to 319 mph, so there is no real issue in rounding there. 612 km/h does round to 380 mph, so it is off a tiny bit. I've specified the range to be 511 - 610 km/h in the main article and moved the comment from the main article to the talk page. Catbar (Brian Rock) 02:54, 22 Aug 2004 (UTC)

It should be noted somewhear on this page that the official Fujita scale measurements are issued after a tornado has passed through an area, not while it is on the ground. It is possible to make educated guesses as to the probable F catagory while a twister is on the ground, but in the end the official Fujita scale measurement is determined after scientist examine radar tracking, eyewitness testomony, and damage. TomStar81 01:36, 9 Sep 2004 (UTC)

Well said, added. -- Solitude 11:56, 14 Sep 2004 (UTC)
  • Relative frequency ... on the whole earth ? Alvaro 23:48, 2005 May 28 (UTC)


Uhm, the percentages in this article add to more than 100%. They need to be verified. Pakaran 13:39, 3 Jun 2005 (UTC)

The numbers still add up to more than 100% Is this just a rounding issue? --Holderca1 04:21, 7 November 2005 (UTC)

Contents

[edit] 7 Categories or 13?

The article refers to "seven categories" (F0 to F6,which are described) and then later says the scale "peaks" at a "hypothetical F12".Now,I am not asking to see any F7 to F12 tornadoes,anywhere...but are they in fact categories on the scale?(The Saffir-Simpson Hurricane Scale goes only to Category 5,which extends from 156 mph to infinity).--Louis E./le@put.com/12.144.5.2 15:01, 19 October '05 (UTC)

Yes there are, although little is known about them. In fact, F6 tends to be an "unofficial" reading, although many have adopted it in the scale as several tornadoes have approached 318 mph (one in 1999 actually recorded a 318 mph gust - and some weather watchers believe it might have been in 319-325 range, although that is unofficial) Since, realistically, the highest a tornado wind will ever get is about 330 mph, they don't mention F7-12 at all. Top of F12 = Mach 1. If an F6 tornado was to ever occur, it would have to be confirmed by the direct wind speed measurement (probably on Doppler Radar) as the damage would be total by the time the F6 winds reach the structures. CrazyC83 19:25, 28 October 2005 (UTC)
I found the wind-speed numbers for the rest of the categories [1]:
F7 - 380-440 mph
F8 - 441-506 mph
F9 - 507-579 mph
F10 - 577-651 mph
F11 - 652-731 mph
F12 - 732 mph - Mach 1 (761.5 mph at sealevel)
--hitssquad 08:38, 21 December 2005 (UTC)
The correct answer is 6. There's such a large amount of confusion on this topic because of the windspeeds. Always remember that the Fujita scale was based on damage -- the windspeed estimates were added later, and the extrapolation to F12 later still. The speeds as correlated to the original F-scale have never been verified -- if anything, they have been proven to be much too high. The so-called "F6" is more a product of media hype after the Doppler-on-wheels analysis of the 99 Moore OK tornado than anything else. The windspeed is irrelevant to the damage scale. If a tornado with 80mph winds somehow managed to cause F5 damage to a neighborhood, it would be rated F5. Even a tornado with a windspeed in the "F6" range would officially go down as an F5, because F5 already represents the highest possible damage level (near to total annihilation of all well-built structures in the damage path). This is a large part of why the Enhanced F-scale is being designed. If anything, F6 should be excised from the description table, and F6-F12 mentioned only as a side note. See the four questions starting at http://www.spc.noaa.gov/faq/tornado/index.html#f-scale1. --Chairman Kaga 04:27, 18 March 2006 (UTC)

[edit] Revision

I have made a minor cleanup revision which addresses some of the cited unresolved issues.

The original F-scale connected the end of the Beaufort Scale and beginning of hurricane windspeeds with the bottom F1 wind speed to Mach 1 with the top F12 wind speed. In practice, it is a damage scale and the associated wind speeds were mere educated guess approximations, only F1-F5 were used, and F0 was added shortly after the introduction of the rating system. F6 is the only other category to have a description, and it is "inconceivable". Remember, it is a damage scale, that said: wind speeds probably do approach ~320 mph, but for how long (momentary gust? 1/100 second? 1 second? 3 seconds?) and at what height (only near the surface - where people are - counts in rating)? No measurements of 318 mph have been recorded. That so frequently abused and misunderstood figure is from a mobile doppler radar measurement taken in May 1999. It was actually 301 mph +/- 17 mph (best estimate from further analysis of about 310 mph), and this was several hundred feet above ground level.

I will write a new, and greatly improved and expanded article in the relative near future. It will also address the new Enhanced Fujita (EF) Scale, which is going into operational use in the U.S. in February 2006. Evolauxia 05:42, 22 November 2005 (UTC)

My plan was to keep one article for the EF/F scale which addresses the history and development of the Fujita to Enhanced Fujita scale, includinh only the current parameters. If anyone thinks there should be separate articles, please discuss. Evolauxia 01:14, 15 January 2006 (UTC)

[edit] Color scheme

Should the color scheme be revised to the same one as the Saffir-Simpson hurricane scale? (It would be based on the same numbers; F0 would get the same color as a tropical storm, F6 should get a purplish color sharper than the F5/Cat 5 color). CrazyC83 23:27, 28 December 2005 (UTC)

I say no. I like the scale colors the way they are now, its easy to read and pleasing to the eye. TomStar81 00:22, 6 January 2006 (UTC)

[edit] EF-Scale

Some choad removed the sections about the Enhanced Fujita scale, without warning, and without creating a separate article about it or anything. So I reverted it.

  • In the EF table, the photographic example for EF-5 is from the 15 Nov 1989 Hunstville, Alabama tornado. I should know because the remnants of my apartment are mingled in the forground and my wife nearly died from her injuries that day. My question is this: Officially, that tornado has been categorized by NOAA as F-4 (evidence such as this photo and my own experience at the site to the contrary). Should it be used here as an example of EF-5 or would it fall there under the new specs? My vote: Our frame apartment building was ripped completely off it's concrete slab foundation and the vinyl flooring was stripped off it. Sections of the sidewalk were ripped up and cars were thrown from the highway 200 yards away into my building. If that's not F-5, I don't know what is. 128.158.14.42 21:54, 12 September 2006 (UTC)
Per the new EF scale guidelines (large file), a totally destroyed appartment/condomenium/townhouse (which is shown here) would take winds of up to 217 mph, well within the new EF-5 range. The Huntsville Alabama tornado was a very high F4 indeed, but may not have been quite an F5. The F and EF scales are meant to correspond, but unfortunately this does not always happen.-Runningonbrains 04:16, 13 September 2006 (UTC)

[edit] F6

I have removed the reference to the Moore, OK tornado as an F6...for several legitimate and scientific reasons.

  • It was operationally assigned a category F5
  • 318 mph is the measurement by the DOW, which is clearly, as stated by the table, in the F5 range
  • Even if 318 mph was an F6, the actual measurement was 318 ± 10 mph, so the uncertainty of this SINGLE measurement is overridden by the dozens of other measurements taken in the same timespan which did not correspond to an F6 rating
  • The 318 mph reading was taken more than 100 feet above the ground. F-ratings, just like Saffir-Simpson Scale ratings are based on SURFACE winds, which were undeniably lower.

This is not to say that there never will be an F6, but this most certainly was not the strongest tornado in history. Had the DOW not been there, we would not even be having this discussion. Runningonbrains 16:25, 21 May 2006 (UTC)

[edit] Removing F6

Why is F6 even listed in the table? There is, by definition, no such thing as an F6 tornado. The windspeeds of strong tornadoes are known to be overestimated by the Fujita scale, hence the Enhanced Fujita scale, which makes an F6 windspeed even more unlikely, if not impossible. F5 windspeed estimates dropped from 261-318 to 201+ with the EF-scale. —Preceding unsigned comment added by 172.146.228.184 (talk • contribs)

Dr. Fujita did consider the possibility that some of the strongest tornadoes might be listed as F6, but gave no descriptions for the damage such a tornado might cause. I think it should be left on there. However, I believe a drastic re-organization of this article is in order—including splitting Fujita scale and Enhanced Fujita scale—once the EF scale is put into effect next February. Runningonbrains 00:00, 25 May 2006 (UTC)


I think the F6 rating should not only STAY, but be applied to the Moore, Oklahoma tornado.

The tornado that had the wind speeds of 318 MPH is on the very border of an F5's upper limit, which is exactly 318 MPH. Therefore, i'd consider it to be an F6, and I doubt i'm the only one that considers it as such (an F6). NOAA chart, depicting this tornado as an F6 Even NOAA classifies this as an F6, and that's an official source. Therefore, it should be regarded as such. User:Raccoon Fox - Talk 18:46, 2 June 2006 (UTC)

Could you describe where on that chart you see that it is an F6...all I can see are 5s. Please read my comments above for other reasons why the tornado does not qualify as an F6. Runningonbrains 03:40, 3 June 2006 (UTC)

There very,very,very likely is sucha thing as an F6 tornado but no-one has observed one yetMike i cool (talk) 13:01, 24 January 2008 (UTC) Mike i cool

Please be sure to read other posts on the talk page- it is clearly stated how the original Fujita scale not only contained a hypothetical F6 tornado, but it actually went up to that of an F12 tornado with winds of Mach 1. Reasons like this are why the Fujita scale was retired and replaced with the open-ended EF5 tornado. In any case, the hypothetical rank of the F6 tornado should be included for historical accuracy. JasontheFuzz (talk) 7:35 EST, 29 April 2008 —Preceding comment was added at 12:36, 29 April 2008 (UTC)

[edit] conversions for mph to km/h seem to be incorrect

for example, 260 mph = 418km/h can we please correct this for all the entries?

[edit] Copied

Most of the tornado descriptions apear copied from http://www.tornadoproject.com/fscale/fscale.htm

They're taken verbatim from Fujita's original formal write-up: Fujita, T. T., 1981: Tornadoes and Downbursts in the Context of Generalized Planetary Scales. J. Atmos. Sci., 38, 1511-1534. I believe it was originally written informally in Fujita, T. T., 1971: Proposed characterization of hurricanes by area and intensity. SMRP Res. Pap. 91, University of Chicago, 42 pp. The list has been reprinted places including http://www.spc.noaa.gov/faq/tornado/f-scale.html. The Tornado Project write-up made minor wording changes.Hebrooks87 11:04, 24 June 2006 (UTC)Hebrooks87
Regardless, it should be cited. Im a bit busy now, will get to it later if someone doesnt take care of it. Runningonbrains 20:38, 24 June 2006 (UTC)

[edit] NOAA on F6

According to NOAA's online tornado FAQ, the May 3, 1999 Moore, OK tornado was not an F6:

" Q: I heard the Oklahoma City tornado was almost "F6." Is that a real level on the original F-scale?

A: Only in untested theory. Fujita plotted hypothetical winds higher than F5; but as mentioned in the previous answer above, they were only guesses. Even if a winds measured by portable Doppler radar (slightly above ground level) had been over 318 mph, the tornado would still be rated "only" F5 since F5 is the most intense possible damage level. On the Enhanced F-scale, there is no such thing as "F6." "

So there you go. There is no such thing as an F6 tornado, even though Ted Fujita plotted out F6-level winds. The Fujita scale, as used for rating tornados, only goes up to F5. Even if a tornado had F6-level winds, near ground level, which is *very* unlikely, if not impossible, it would only be rated F5. The damage that a tornado (an F5!) with winds at the hypothetical F6 level would produce can only be speculated on, and probably wouldn't be all that worse than a tornado with F5 winds, since the only things left standing under F5 winds are reinforced concrete structures and four-story condos with their top two levels blown off. Therefore, hopefully with no objections, I am going to do some editing on the section about 'F6 tornados'.

Here is the source of my quote, the online tornado FAQ, from NOAA:

[2] —Preceding unsigned comment added by 172.145.139.17 (talk • contribs)

Alright, same editor. I added a couple of sentances explaining that F6 tornados don't exist by definition, and a link to the NOAA tornado FAQ (I don't know how to make superscripts or endnotes), and I removed this sentance:
"If this level is ever achieved, evidence for it might only be found in some manner of ground swirl pattern, for it may never be identifiable through engineering studies."
What the heck? What the heck does that even mean; that's just stupid. There isn't really any reason why it couldn't be identifiable through engineering studies- things like 2x4s punched into tree trunks or grain silos could be used. And I'm not sure there would be any ground swirl patterns unique to F6 tornadoes, especially since any F6 windspeed, if it exists, which it most likely doesn't, would be only marginally above F5 and would leave roughly the same ground swirly pattern. And that is if 'ground swirl patterns' can even be used to identify the strength of tornadoes, which I doubt. The forward motion of the storm would, I would think, have a bigger impact on the quantity of dirt blown around. And finally, if I recall correctly, not all tornadoes extend all the way to the ground. Technically the circulation must touch the ground to be classified as a tornado, but if it is three inches above ground, it's not going to matter. —Preceding unsigned comment added by 172.145.139.17 (talk • contribs)

There is an F6 but no-one has added it yetMike i cool (talk) 13:03, 24 January 2008 (UTC) Mike i cool

Hey; if a sentence is unsourced and dubious, feel free to just remove it with an edit summary noting that it's "unsourced and dubious". You don't have to write a paragraph debunking it, though it might be helpful for whoever tried to add it into the article. :) Thanks for helping out! —AySz88\^-^ 13:27, 26 September 2006 (UTC)

[edit] The Last Tornado rated on the F-Scale?

Does anyone know when, where and what rating the last tornado that occurred in the USA before the EF-Scale takes over? I think that might be at least of some historical note. LK Thurisaz 16:16, 6 February 2007 (UTC)

There was a report of wind damage in San Marcos, Texas early in the morning on the 13th which may or may not have been a tornado, but the last definate tornado was in Troy, Texas on the 12th. I may shoot them an email asking about it. -Runningonbrains 19:58, 29 January 2007 (UTC)
Officially, it does appear to be this one: Before the winter storm hit Texas on January 13, a tornado touched down in the central Texas town of San Marcos. It registered F1 by local weather and police authorities. No one was reported injured or killed, but moderate damage was sustained, including damage near the local police station and a light fixture manufacturing business. No other tornadoes were reported from the storm. The tornado was an estimated 100 yards wide and three-tenths of a mile long. —The preceding unsigned comment was added by LK Thurisaz (talk • contribs) 16:35, 6 February 2007 (UTC).

[edit] Fujita scale still in use

It's incorrect to call the Fujita scale "obsolete." The only country that will use the EF scale is the US. As far as I know, every other country that uses the Fujita scale will continue to do so. I don't think any of them plan to go through the engineering efforts associated with the damage indicators. Hebrooks87 12:15, 1 February 2007 (UTC)

You may be right, but the degree indicators are so easily available on the Internet that you and I could use it to make assessments, so it is possible that other countries (probably the first will be Environment Canada) will adopt it this year. CrazyC83 22:38, 13 February 2007 (UTC)
The Fujita scale description was easily available as well and could be used to make assessments. One of issues with the EF scale is that damage indicators are tied to US design and construction practice. MSC is thinking about it in Canada, but they'll watch what happens in the US for a couple of years. They may try an experiment where they do parallel ratings in 2008. The effort to develop damage indicators for Europe consistent with the US DOIs would be large and I don't know of anyone who's planning to do it. Some of the Europeans are quite unhappy that comparisons with the US will be difficult, at best, in the future. Hebrooks87 19:44, 14 February 2007 (UTC)

[edit] F6 above and beyond...

Since Dr. Fujita's original scale went all the way up to F12 (shown in the Beaufort/Fujita/Mach graphic) shouldn't that at least be mentioned in the article? - Aerobird Target locked - Fox One! 14:47, 1 February 2007 (UTC)

Yes it shouldMike i cool (talk) 13:04, 24 January 2008 (UTC)Mike i cool

It is. Read the article. -RunningOnBrains 03:11, 25 January 2008 (UTC)