El Reno Oklahoma tornado downgraded to EF3

[Elaine Spencer]

I wonder if there isn't something else going on here besides just concern for consistent data keeping. Who might have an interest in maintaining that El Reno wasn't really an EF-5 -- insurance companies? Local businesses or real estate agents? Someone else?

IIRC there was another EF-5 near El Reno on 5/24/11. Since the town of El Reno itself did NOT get hit then or on 5/31, perhaps some persons or groups in the community would rather its name not be associated with EF-5 tornadoes?

 

[Justin Turcotte]

Here is the problem according to a Doswell blog post back in June http://cadiiitalk.blogspot.com/2013/06/the-ef-scale-ratings-brouhaha.html

The following is a recent directive from the NWS Director, Dr. Louis Uccellini:
[h=5]Directive NWSI 10-1604, Post-Storm Data Acquisition, requires us to use the EF scale, which is an impact-based rating assigned to a tornado after extensive investigation of the damage it caused. EF ratings are determined by observed damage rather than measured wind because we have no consistent way to measure wind speed for every tornado that occurs. Adhering to NWSI 10-1604 ensures we continue to use consistent methodology throughout the country for assigning EF ratings.[/h]

 

[Jeff Snyder]

Here is the problem according to a Doswell blog post back in June http://cadiiitalk.blogspot.com/2013/06/the-ef-scale-ratings-brouhaha.html

The following is a recent directive from the NWS Director, Dr. Louis Uccellini:
Directive NWSI 10-1604, Post-Storm Data Acquisition, requires us to use the EF scale, which is an impact-based rating assigned to a tornado after extensive investigation of the damage it caused. EF ratings are determined by observed damage rather than measured wind because we have no consistent way to measure wind speed for every tornado that occurs. Adhering to NWSI 10-1604 ensures we continue to use consistent methodology throughout the country for assigning EF ratings.

The issue is that we don't have a consistent way to assess tornadoes using damage either since not all tornadoes affect the same DIs. The EF scale is good in terms of laying out DoDs for DIs, but the tornadoes themselves aren't consistent in terms of hitting things. We're all very familiar with one of the biggest issues with relying upon damage to infer tornadic wind speeds -- we're limited entirely by the damage that's present. In rural areas, there's an obvious bias towards low EF scale categories since the ability to accurately assess intensity is detrimentally affected by the improbability of high-end DoDs and DIs being directly impacted by a given tornado. I'm not saying that the NWS isn't following its policies, but I think the policies are limiting and dearly in need of updating. This all assumes that the reason to assign an EF scale rating to a tornado is to estimate the near-ground winds within the tornado. Estimating winds by assessing damage, though, can be very difficult with very high uncertainty.

Applying a methodology consistently is important, but that means, IMO, that the NWS must develop a method by which observational data can be used in the EF scale assignment process. I suspect that something like this is in the works, but it still seems silly to me to ignore observational data in the name of maintaining a consistently inconsistent method.

 

[Jacob Ferden]

I'm just a non-met yahoo chaser, but per the directive they have been told to follow, it seems to me that they made the right decision...damage scale + lack of clear evidence of ef5 damage = downgrade.

The greater issue here IMO is the scale itself...Fujita's original scale was flawed, and this scale is flawed...so at some point a new, better scale needs to be developed, I suppose...although I also tend to think the greater issue as opposed to whether it was a 3 or a 5 on some set scale is what the wind speeds actually were...IMO the whole point should be about how high the wind speeds can get, and how those wind speeds affect structures.

It just seems to me that an effect on a structure has less to with whether a tornado was an EF-3 or and EF-5...but a LOT to do with if the winds were, say, 150 mph or 250 mph...they can come up with whatever scale they want, but at the end of the day, that's what's relevant.

So as long as the data still exists on El Reno, changing a rating on a pre-defined scale shouldn't matter all that much. Good can still come from it.

 

[Mike Smith]

Jacob, while I agree the original scale was not perfect, the evidence seems to indicate the original was much better than the EF. The original went up to 319 mph. The original explicitly allowed for measured winds. See: http://meteorologicalmusings.blogspot.com/2013/08/extremely-odd-decision-from-national.html

Or, am I missing your point. If so, please clarify. I'd like to better understand.

 

[Shawn Schuman]

Jacob, while I agree the original scale was not perfect, the evidence seems to indicate the original was much better than the EF. The original went up to 319 mph. The original explicitly allowed for measured winds. See: http://meteorologicalmusings.blogspot.com/2013/08/extremely-odd-decision-from-national.html

Or, am I missing your point. If so, please clarify. I'd like to better understand.

The proposal for the EF-scale, at least, explicitly permitted remote-sensed equipment as well, and obviously the attempts to standardize the huge degree of subjectivity using DI/DODs was a big step in the right direction. I do think the wind speeds need to be reevaluated, possibly somewhat closer to the original F-scale on the higher ratings, but it's obviously a very difficult problem. I think they had the right idea with making EF5 open-ended rather than providing a range, though.

To me, it's all about managing and ideally eliminating as many of the variables and inconsistencies as possible. Unless we can devise some way to remotely sense every tornado that occurs, there will simply always be frustrating inaccuracies and subjectivities. It's just a part of the deal. Incidentally, that's why I don't think it makes sense to try and preserve the current climatology when you have a chance to improve its accuracy.

 

[Mike Smith]

The proposal for the EF-scale, at least, explicitly permitted remote-sensed equipment as well,

But, in NWS practice, this is not the case.

With the original,

• F = measured wind speed
• f = estimated wind speed from damage

I don't understand the objections that going back to this would somehow skew the database. It would be clearly marked as to the type of observation that is the basis of the F-rating.

I also do not like the open-ended nature of the EF scale because it provides no useful guidance for design purposes. See: http://meteorologicalmusings.blogspot.com/2013/08/following-up-on-el-reno-tornado.html

We would be better off, in every way, going back to the original F-Scale. Ted's estimate of 319 mph is looking awfully good.

 

[Robert Edmonds]

So will the width of the El Reno tornado be assessed without radar then?

 

[f.vanalstine]

For what it is worth, I saw many destroyed cars from the Moore tornado of May 20th, and some near the medical center that although damaged, never moved an inch. In contrast, nothing I saw at Moore was even remotely close to the utter destruction of the Twistex vehicle.

Methinks the main El Reno tornado could be best described as a huge EFF1/EF0 tornado with several random and very fast moving tornadoes embedded within it, some up to EF5 ratings. I am glad that we never got very close to the monster.

Frank VA

 

[Jeff Duda]

The greater issue here IMO is the scale itself...Fujita's original scale was flawed...

How is the scale flawed?

 

[Patrick Marsh]

Jacob, while I agree the original scale was not perfect, the evidence seems to indicate the original was much better than the EF. The original went up to 319 mph.

The original scale went up to Mach 1. 319 was the break point of F5/F6. Fujita went on to hypothesize that F6 damage would be indistinguishable to F5 damage and therefore would not be used.

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

 

[Mike Smith]

Here are some additional thoughts...

What would be the advantage of admitting weather science made a mistake in converting from the original Fujita Scale to the EF scale? I see at least three advantages:

1) The top value (319 mph) is far more useful than "more than 200 mph." The 319 value is apparently quite accurate, at least based on what now we know. Might there be a peak gust of 325 somewhere? Sure. But, 319 as a top value seems close.


2) The Rozell, Kansas, tornado would be rated:
F-4 (measured winds) AND
f-2 (estimate from damage)
People doing a database search would be free do an "estimate-only" search and it would appear nothing has changed. Consistency would be preserved. Building designers could do a search by wind speed and retrieve much more precise information.


3) So much work was done with the original Fujita scale (Tom Grazulis "Significant Tornadoes", and others) we would not have to go back and re-rate the tornadoes prior to 2007 to accommodate changes in EF or some third index.



It seems to me this has huge advantages and no downside. ​

 

[Patrick Marsh]

Mike, you must have missed my post above yours.

The Fujita scale did not top out at 319. That was just the break point between F5/F6.

 

[Dave C]

The EF scale should not mention wind speed at all if ratings are going to be based on damage alone. With this treatment of observed data its clear that we can take either of the Moore tornadoes or a Joplin, move them into an open field, and now they are suddenly EF3 or weaker. This is insane, it reeks of human frivolity and politics, and in my opinion is insulting to any scientific, objective approach. Anyone who can side against radar in favor of subjective damage assessment is barking up the wrong tree. Just because one EF5 happens in the city and another in open fields should not make them unequal when scientifically evaluated. This downgrade is a load of you know what...

As far as nonsense about preserving the integrity of databases when switching systems - we have computers. We can do any conversions necessary by marking which parameter set was used to evaluate each event. Not to mention that due to the obvious and subjective rating system - none of it means much anyway. In 20 years I will be really surprised if radar measurements are not the ONLY standard by which a tornado is rated.

 

[Stan Rose]

It seems to me this has huge advantages and no downside.

The downside is under the F scale, stronger winds were attributed to tornados than were actually necessary to cause damage (due to construction weaknesses etc) That was the main reason for switching to the EF scale--the realization that you didn't need 150 mph winds to take out some houses. This was extensively demonstrated.