Fujita Scale

NZstorm · Unread post by **NZstorm** » Sun 15/01/2006 22:40

The Americans have made a revision of the fujita scale. They have reduced the wind speeds for each damage category.

Original F-scale
Fujita Tornado Damage Scale
Developed in 1971 by T. Theodore Fujita of the University of Chicago
No longer used operationally -- see the Enhanced F Scale.

SCALE WIND ESTIMATE *** (MPH)
F0 < 73
F1 73-112
F2 113-157
F3 158-206
F4 207-260
F5 261-318
Source: http://www.spc.noaa.gov/faq/tornado/f-scale.html

Enhanced F Scale for Tornado Damage
An update to the the original F-scale by a team of meteorologists and wind engineers and implemented in the U.S. in February 2006.

SCALE WIND ESTIMATE *** (MPH)
F0 65-85
F1 86-110
F2 110-135
F3 136-165
F4 166-200
F5 Over 200
Source: http://www.spc.noaa.gov/faq/tornado/ef-scale.html

NZstorm · Unread post by **NZstorm** » Mon 16/01/2006 20:51

Interestingly, the revised F-scale suggests that tornadic winds upto 140km/h (75kts) are only likely to produce F0 damage.

And a higher level of F scale damage is now thought to be caused by less wind.

Now that the US is changing from the F scale to the Ehanced F scale, shud the rest of the world follow suit?

NZ Thunderstorm Soc · Mon 16/01/2006 21:35

I hate the way Yanks change just to make suit

Who do they think they are?

...they can't even spell proparlie

JohnGaul
NZTS

Michael · Unread post by **Michael** » Mon 16/01/2006 22:43

rember they think thetre the only nation on the planet

NZ Thunderstorm Soc wrote:I hate the way Yanks change just to make suit
Who do they think they are?

...they can't even spell proparlie
JohnGaub]

gllitz · Unread post by **gllitz** » Tue 17/01/2006 11:30

Hello All-
I am a "yank" - displaced, mind you, but born American. I don't think it is a matter of "Because we do it, now the rest of you have to" (...although there ARE some things going on right now with the US which I COMPLETELY disagree with, but won't go there as this is weather only...)
Anyway, go to the links explaining the scale and have a gander at the 95-page pdf file explaining WHY they use it...all the research and why Dr Fujita's scale was "enhanced" is there...

Just my $0.02.

Willoughby · Unread post by **Willoughby** » Tue 17/01/2006 12:10

The torro scale developed in 1972 by Dr. Meaden based on the Beaufort scale still seems better than the fujita scale.. or has these changes rectified the holes in the F-scale?

http://www.torro.org.uk/severeweather/tscale.htm

TonyT · Unread post by **TonyT** » Tue 17/01/2006 12:22

One side effect of using the new scale is that there will be more F4 and F5 reported torndaoes each year - a situation which will allow the insurance industry to justify raising premiums and the climate change fraternity to say "I told you so", as well as a range of other downstream effects. People very quickly forget that the goalposts have been moved, and in a few years will start quoting statistics which have been debased by this change. Unfortunate really...

GraemeWi · Unread post by **GraemeWi** » Tue 17/01/2006 12:59

Somebody send a copy to TVNZ and The Herald - they will be mortified to find their favourite wind reporting term of 'mini tornado' doesn't exist.

Cheers,

G

Weather Watcher · Unread post by **Weather Watcher** » Tue 17/01/2006 14:22

TonyT wrote:One side effect of using the new scale is that there will be more F4 and F5 reported torndaoes each year.....

I don't think this is a correct assumption. The Fujita scale is based on damage resulting from a tornado, and uses this damage to estimate the relevant wind speeds. The way I read this change is that is the Americans are just revising the estimated wind speeds associated with each F number (based on recent engineering research). The relationship between damage and F number stay the same.

TonyT · Unread post by **TonyT** » Tue 17/01/2006 14:51

Yes, I see your point, you are probaly correct, in that we dont go out and measure the wind speed of every tornado and assign it an F value, but rather look at what it does and infer a wind speed from that. My bad.

Michael · Unread post by **Michael** » Tue 17/01/2006 16:37

perhaps have the f scale to f6 or possibly open ended to some degree

NZ Thunderstorm Soc · Tue 17/01/2006 19:21

I'm going to start up my own scale, just like what I did for thunderstorm predictions

JohnGaul
NZTS

andrew begent-peers · Tue 24/01/2006 17:13

Foggy Hamilton wrote:The torro scale developed in 1972 by Dr. Meaden based on the Beaufort scale still seems better than the fujita scale.. or has these changes rectified the holes in the F-scale?

http://www.torro.org.uk/severeweather/tscale.htm

Just out of interest, some States are now adopting the Torro Scale, apparantly Ted Fujita assumed only America studied tornado's and measured tornado's. When in fact England gets more tornado's than any other country in the world per sq mile and the English were the first to study tornado's

Andrew Begent - Peers
TORRO

NZ Thunderstorm Soc · Tue 24/01/2006 17:36

andrew begent-peers wrote:
Just out of interest, some States are now adopting the Torro Scale, apparantly Ted Fujita assumed only America studied tornado's and measured tornado's. When in fact England gets more tornado's than any other country in the world per sq mile and the English were the first to study tornado's

Andrew Begent - Peers
TORRO

I would tend to agree with you on that

JohnGaul
NZTS

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