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Enhanced F Scale for Tornado Damage
NOAA ^ | Feb 2007 | NOAA

Posted on 05/08/2007 6:04:05 PM PDT by xcamel

Enhanced F Scale for Tornado Damage

An update to the the original F-scale by a team of meteorologists and wind engineers, to be implemented in the U.S. on 1 February 2007.


FUJITA SCALE DERIVED EF SCALE OPERATIONAL EF SCALE

F Number Fastest 1/4-mile (mph) 3 Second Gust (mph) EF Number 3 Second Gust (mph) EF Number 3 Second Gust (mph)

0 40-72 45-78 0 65-85 0 65-85

1 73-112 79-117 1 86-109 1 86-110

2 113-157 118-161 2 110-137 2 111-135

3 158-207 162-209 3 138-167 3 136-165

4 208-260 210-261 4 168-199 4 166-200

5 261-318 262-317 5 200-234 5 Over 200

*** IMPORTANT NOTE ABOUT ENHANCED F-SCALE WINDS: The Enhanced F-scale still is a set of wind estimates (not measurements) based on damage. Its uses three-second gusts estimated at the point of damage based on a judgment of 8 levels of damage to the 28 indicators listed below. These estimates vary with height and exposure. Important: The 3 second gust is not the same wind as in standard surface observations. Standard measurements are taken by weather stations in open exposures, using a directly measured, "one minute mile" speed.


Enhanced F Scale Damage Indicators

NUMBER (Details Linked) DAMAGE INDICATOR ABBREVIATION

1 Small barns, farm outbuildings SBO

2 One- or two-family residences FR12

3 Single-wide mobile home (MHSW) MHSW

4 Double-wide mobile home MHDW

5 Apt, condo, townhouse (3 stories or less) ACT

6 Motel M

7 Masonry apt. or motel MAM

8 Small retail bldg. (fast food) SRB

9 Small professional (doctor office, branch bank) SPB

10 Strip mall SM

11 Large shopping mall LSM

12 Large, isolated ("big box") retail bldg. LIRB

13 Automobile showroom ASR

14 Automotive service building ASB

15 School - 1-story elementary (interior or exterior halls) ES

16 School - jr. or sr. high school JHSH

17 Low-rise (1-4 story) bldg. LRB

18 Mid-rise (5-20 story) bldg. MRB

19 High-rise (over 20 stories) HRB

20 Institutional bldg. (hospital, govt. or university) IB

21 Metal building system MBS

22 Service station canopy SSC

23 Warehouse (tilt-up walls or heavy timber) WHB

24 Transmission line tower TLT

25 Free-standing tower FST

26 Free standing pole (light, flag, luminary) FSP

27 Tree - hardwood TH

28 Tree - softwood TS

A 95 page PDF file explaining the development and makeup of the Enhanced F-scale now is available, both here at SPC and from the Texas Tech server.


Back to The Online Tornado FAQ

Enhanced F-scale Website

SPC Home Page



TOPICS: Extended News; Miscellaneous
KEYWORDS: efscale; enhanced; fujita; tornados
This is to clear up why it seems the press is "under reporting" tornado wind strength, in light of the recent events.

I doubt Dr. Fujita would be very happy with this "new scale"

1 posted on 05/08/2007 6:04:09 PM PDT by xcamel
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To: xcamel

Who knows, he said his old scale was not perfect and it needed improvements.


2 posted on 05/08/2007 6:07:40 PM PDT by aft_lizard (born conservative...I chose to be a republican)
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To: xcamel
It's not that the wind is blowing, it is what the wind is blowing...
3 posted on 05/08/2007 6:07:42 PM PDT by mnehring (McCain '08 -------------------------------------- just kidding...)
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To: xcamel

Clear as mud to me:’)


4 posted on 05/08/2007 6:08:30 PM PDT by CindyDawg
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To: xcamel

Why would he be unhappy with it? He agreed his scale was flawed.


5 posted on 05/08/2007 6:14:02 PM PDT by Psycho_Bunny
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To: mnehrling
True. A plastic bottle cap at 200 mph can and will kill you... now imagine 80% of an entire town... airborne.... at 200 MPH
6 posted on 05/08/2007 6:14:49 PM PDT by xcamel (Press to Test, Release to Detonate)
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To: Psycho_Bunny

His comment about “flawed” had to do with under reporting strength/damage ratios, and it was a huge political (politically correct) fight to get number approaching 300 mph even discussed openly. He knew higher was not only possible, but likely. The technology to accurately measure 10 second bursts (not 3 second like was agreed to) didn’t exist at the time. It does now, and he was dead on right... they (NOAA) are underreporting on purpose.


7 posted on 05/08/2007 6:20:50 PM PDT by xcamel (Press to Test, Release to Detonate)
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To: xcamel
From one of your links: http://www.spc.noaa.gov/efscale/ Over the years, the F-Scale has revealed the following weaknesses: It is subjective based solely on the damage caused by a tornado No recognition in difference in construction Difficult to apply with no damage indicators if the 3/4-mile wide tornado does not hit any structures, what F-scale should be assigned? Subject to bias Based on the worst damage (even if it is one building or house) Overestimates wind speeds greater than F3
8 posted on 05/08/2007 6:21:38 PM PDT by aft_lizard (born conservative...I chose to be a republican)
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To: xcamel

Well if it’s any consolation peak shear force winds were as high as 240 knots according to radar for the Greensburg Tornado.


9 posted on 05/08/2007 6:23:05 PM PDT by aft_lizard (born conservative...I chose to be a republican)
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To: aft_lizard
Known flaw with a damage only scale. Multipoint Doppler solves this with 3D wind speed readings. - Dr. F used to use the analogy of “If a tree falls in the woods and nobody hears it, was it loud?”
10 posted on 05/08/2007 6:27:45 PM PDT by xcamel (Press to Test, Release to Detonate)
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To: xcamel

OK then a reply would be to that is, “Which is worse if you are driving a SUV getting hit by a yugo doing 100mph or getting hit by a semi doing 75 mph?”


11 posted on 05/08/2007 6:30:49 PM PDT by aft_lizard (born conservative...I chose to be a republican)
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To: xcamel

Let me correct this:

OK then a reply would be to that is, “Which is worse if you are driving a SUV getting hit by a yugo and it is going 100mph or getting hit by a semi going 75 mph?”


12 posted on 05/08/2007 6:32:25 PM PDT by aft_lizard (born conservative...I chose to be a republican)
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To: aft_lizard

“Yes”
:-)


13 posted on 05/08/2007 6:55:20 PM PDT by xcamel (Press to Test, Release to Detonate)
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To: aft_lizard; xcamel
...or a straw @ 400 mph....straight though a telephone pole.
14 posted on 05/08/2007 8:08:13 PM PDT by skinkinthegrass ( just b/c, you suffer from paranoia, doesn't mean they're not out to get you....Run, Fred, Run :^)
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To: skinkinthegrass

It’s not the wind alone that does that, it’s the pressure differences inside of the cyclone that can, for lack of a better word, soften the telephone pole.

I guess my point I am trying to make is that the size+speed is more important than just speed alone.


15 posted on 05/08/2007 8:25:00 PM PDT by aft_lizard (born conservative...I chose to be a republican)
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To: aft_lizard

it all comes down to mass in motion — basic physics.


16 posted on 05/09/2007 4:29:28 AM PDT by xcamel (Press to Test, Release to Detonate)
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To: xcamel

Having worked in the structural engineering field for a few years, I can see the corrolation between the different levels of intensity of a tornadic event and the structures it “could” effect, depending on that force acting on the structure...

But...

To me its all destructive, and dependent upon a few other factors in how a structure “might” fail...And it all happens so fast it is just impossible to design effectively enough to counter all the variables you could possibly compile into the design...

You can do your best, and there are guidelines and industry standards...But you can only do so much...

I would say that its important to go as far as you can with what you have available, but always look for ways to encourage people to prepare for the worst, and create plans and shelter you can get to very quickly that anyone can take advantage of to protect lives...

Anyone who has looked at the devastation in that town, if you notice how many (below ground) shelters beside those destroyed homes in those pictures, showed the doors open, know that those shelters saved lives, and that is the best thing yet out of this whole ordeal...


17 posted on 05/09/2007 5:50:14 AM PDT by stevie_d_64 (Houston Area Texans (I've always been hated))
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To: stevie_d_64
Right on the money.
Photo #20 from the KC arial site is a perfect example of a "safe room" built into the structure of the house. It mas mostly undamaged, and saved an entire family.


18 posted on 05/09/2007 5:57:57 AM PDT by xcamel (Press to Test, Release to Detonate)
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To: xcamel
I didn't see , "Common soda straw half way through palm tree," listed up there.

5.56mm

19 posted on 05/09/2007 6:02:21 AM PDT by M Kehoe
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To: xcamel

Those look like APB’s (Anthony Power Beams) coming across the top of those internal wall frames out from theat center room (shelter)...

I saw that pic yesterday, but it didn’t register till you mentioned it...

If they had more incentive to make “internal” armored rooms that would either be “no cost” or give a substantial insurance break to homes built in areas like this would really save a lot of lives if you ask me...

I’m having one built into our new home this time...No breaks for us, except peace of mind, and the skill to make use of it when the need arises...


20 posted on 05/09/2007 10:20:34 AM PDT by stevie_d_64 (Houston Area Texans (I've always been hated))
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