Tornadoes that should have been rated F5/EF5

[Royce Sheibal]

Hallam, Nebraska May 2004 might deserve another look. 2.5 Miles wide, with EF-4 Damage occurring in the Town of Hallam on the north edge of the rotation. Moved a whole train a pretty good distance. I'm guessing due to the lack of things to destroy in direct proximity to the maximum velocity it might be hard to prove between EF4-EF5. Such is the case with many of the F4's in Nebraska.

 

[Pete Kustra]

Another possibile candidate is the Edmonton, Alberta tornado of July 31, 1987. Its estimated peak wind speeds (268 mph) were within the F5 category.

Also, while it clearly wasn't an EF5, the Nickerson-Hutchinson, KS tornado of July 13 this year could potentially have been an EF4, considering the fact that trees in its path were described as being completely debarked, and its peak winds were precisely at the boundary between EF3 and EF4-level.

 

[calvinkaskey]

A lot of the upgrade talk for that tornado was based on this photo of the Cherokee Valley Rd area...

View attachment 10489

It was found that most of the homes in this area were not properly anchored, so EF5 was not given, although this is still obviously extreme damage. FFC does tend to be a conservative office in general, there was a tornado in Polk/Floyd Counties on 3/15/08 that was looked to be a strong candidate for EF4, but was rated EF3.

I have that pic saved on my comp.

 

[Shawn Schuman]

Oops, typo. Anyhow, is there a dividing line between what degree of soil scouring constitutes F4/EF4 and F5/EF5 damage? Several tornadoes which have caused deep scouring haven't been rated F5/EF5.

The problem with ground scouring and vegetation damage in general is that there are so many variables. The type of grass/vegetation, its condition, the soil type/conditions/moisture, whether or not debris loading was an obvious factor, etc. There's no good way to handle all of that currently, so scouring isn't used directly in damage surveys. It is a useful bit of context - significant scouring near a swept-away building might provide added confidence in an EF5 rating, for instance - but then it's still up to the people doing the surveys as to how they incorporate that information. I think the best we can say for certain at the moment is that scouring and extreme vegetation damage is quite often associated with very violent tornadoes, but its presence/absence isn't automatically evidence for/against a certain rating.

 

[Greg Campbell]

There is a big EF-scale rewrite effort in place now - one of the suggestions was to add more info into the database so radar-based winds, non-normal damage, etc. can be listed.

Thank *bleep*!
If the EF scale is to be correlated with wind speed (sustained, 3 sec gust, whatever) in any way, ignoring solid doppler data seems rather.. "stupid" (The polite word.) Given variability in construction and interpretation, one would think that a solid physical wind speed measurement would take precedence over all other evidence. But I guess that would make too much sense. This whole issue smacks of politics. Is there a back-story we should know about?

 

[rdale]

No back story - just remember that the NWS is a government organization run on policies. It's a big ship with a small rudder. The rudder works - it just isn't fast. No reason to think anything sinister...

 

[Shawn Schuman]

Thank *bleep*!
If the EF scale is to be correlated with wind speed (sustained, 3 sec gust, whatever) in any way, ignoring solid doppler data seems rather.. "stupid" (The polite word.) Given variability in construction and interpretation, one would think that a solid physical wind speed measurement would take precedence over all other evidence. But I guess that would make too much sense. This whole issue smacks of politics. Is there a back-story we should know about?

I'd imagine the biggest problem is that radar observations =/= actual wind speed obs, so there's plenty of uncertainty as to how, exactly, that sort of thing should be handled. Radar data may be of varying quality and usefulness from situation to situation, so what sort of rules do you use to determine what's acceptable evidence and what isn't? It probably won't be at or near ground level, so how do you translate data from, say, 50 or 100 or 200m AGL? At what point is it just too far above ground level to be useful as a representation of a tornado's intensity near the surface? Does it have to be a sustained velocity? How long? Is a 225 mph velocity for 3 seconds at 150m AGL enough to assign an EF5 rating?

Obviously it makes sense to use all available data to rate tornadoes, especially given the inherent flaws in the damage rating system (sparsity/lack of DIs being the most obvious), but it also makes sense to approach it intelligently and make sure you have a plan in place for how to implement it. I don't have any issue with that. I do think it was a bad idea to downgrade El Reno again after first making the call to upgrade, especially given that the velocities we're talking about were so far in excess of the EF5 threshold, but that's really the only issue I have with it.

 

[Jeff Duda]

I'd imagine the biggest problem is that radar observations =/= actual wind speed obs, so there's plenty of uncertainty as to how, exactly, that sort of thing should be handled. Radar data may be of varying quality and usefulness from situation to situation, so what sort of rules do you use to determine what's acceptable evidence and what isn't? It probably won't be at or near ground level, so how do you translate data from, say, 50 or 100 or 200m AGL? At what point is it just too far above ground level to be useful as a representation of a tornado's intensity near the surface? Does it have to be a sustained velocity? How long? Is a 225 mph velocity for 3 seconds at 150m AGL enough to assign an EF5 rating?

It would be awesome if someone like Jim LaDue, Jeff Snyder, or Chris Karstens would comment on this. There are laboratory studies on tornado structure that, AFAIK, suggest there is a somewhat robust vertical structure of tornado winds, so radar measured winds at some height aloft could be converted, likely in a statistical or probabilistic sense, to 10-m AGL. That may very well be a point of discussion in the EF-scale update. I suppose we'll find out in time.

 

[Shawn Schuman]

It would be awesome if someone like Jim LaDue, Jeff Snyder, or Chris Karstens would comment on this. There are laboratory studies on tornado structure that, AFAIK, suggest there is a somewhat robust vertical structure of tornado winds, so radar measured winds at some height aloft could be converted, likely in a statistical or probabilistic sense, to 10-m AGL. That may very well be a point of discussion in the EF-scale update. I suppose we'll find out in time.

Yeah, I'd love to hear from any of them. I've read a few papers that seem to suggest the same, but I don't really know how applicable it is here or how much confidence there would be in using it as a basis for ratings. It'll be interesting to see how it's all handled if/when radar data is eventually incorporated into the rating process. I'm sure there's also some discussion about whether it'll further skew climatology and such since tornadoes in the Plains are more likely to be observed by radar than anywhere else, but the record is already so flawed and incomplete that I'm not sure it makes much difference. Better to skew things in the direction of improved accuracy, I think.

 

[calvinkaskey]

I think it would be of utmost importance compared to the other potential ef-5s to look at the May 31, 1985 outbreak for any more ef-5s due to it's location away from normal tornado alleys and potential for an outbreak to hit an extremely populated area in the east.

 

[Pete Kustra]

Could the Lebanon, KS tornado of 5/27/2013 have been a candidate for an EF4 rating? The TIV crew reportedly recorded a gust of 175 mph.

 

[Brian R]

I am going out on a limb here but I would say the November 17 2013 Washington Illinois tornado and the 2015 Rochelle Illinois tornado should have been rated EF-5

 

[Jeff Duda]

I am going out on a limb here but I would say the November 17 2013 Washington Illinois tornado and the 2015 Rochelle Illinois tornado should have been rated EF-5

Your claim would be much more convincing if you had some sort of data or factual argument to accompany it.

 

[Brian R]

Your claim would be much more convincing if you had some sort of data or factual argument to accompany it.

I am going by the amount of damage I personally saw

 

[rdale]

It's not the amount of damage - it's the degree.