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Enhanced Fujita Ratings Debate Thread (1 Viewer)


locomusic01

Member
Messages
84
Location
Pennsylvania
Yeah, I've got the Storm Data photos and a few really poor quality newspaper scans. The ones Dean has are high-quality color photos. He posted a couple of them to his website years ago, but it seems they're inaccessible now even with the Wayback Machine. Storm Data does list the names of some of the people who supplied photos, so some day I may see if I can track some of them down.

I checked my archives and I actually do have two color photos:





Edit: Didn't see your second post - nice find! I was hopeful maybe the linked NWS page would have more photos but it's gone now and there don't seem to be any archived copies of it. Bummer. Might contact Goodland and see if they've still got anything, though.
 
Messages
74
Location
Lenexa, KS
Yeah, I've got the Storm Data photos and a few really poor quality newspaper scans. The ones Dean has are high-quality color photos. He posted a couple of them to his website years ago, but it seems they're inaccessible now even with the Wayback Machine. Storm Data does list the names of some of the people who supplied photos, so some day I may see if I can track some of them down.

I checked my archives and I actually do have two color photos:





Edit: Didn't see your second post - nice find! I was hopeful maybe the linked NWS page would have more photos but it's gone now and there don't seem to be any archived copies of it. Bummer. Might contact Goodland and see if they've still got anything, though.
Besides this tornado and the Camp Crook tornado there are two other tornadoes that I know of that granulated vehicles and farm equipment and those were Jarrell, Texas on May 27, 1997 and the Chapman/Solomon tornado on May 25, 2016. The Chapman/Solomon tornado ripped up CWR railroad tracks.
 
Messages
74
Location
Lenexa, KS
Yeah I don't doubt Chapman was EF5 strength at some point (and I think the surveyors said as much)
Here is the survey from the Camp Crook tornado on June 28, 2018. If you also read further a large farm outbuilding was destroyed and it foundation was violently ripped from the ground. While that is not a really strong structure but the foundation being ripped out of the ground sounds quite impressive. Though it also could have been a weak foundation. https://www.weather.gov/unr/2018-06-28
 

Equus

Member
Messages
1,161
Location
Saragossa, AL
I had mentioned on the old TW that the Chapman tornado's damaging of mainline Class One CWR (continuously welded rail) is as far as I know unprecedented in the modern era. Modern mainline rail weighs ~130 lbs per yard and is thermite-welded in lengths of at least hundreds of feet. Older lighter jointed rail in past decades, sure, it reportedly happened occasionally, but never on a track with modern standards and rail weight. Union Pacific repaired it pretty fast so no analysis was done as far as I know, but if the damage was dealt via wind and not impact with big debris at high speed (which is very possible) that absolutely counts as "incredible damage".
 

locomusic01

Member
Messages
84
Location
Pennsylvania
I'm still not really sure what to make of that rail line damage. I've certainly never seen or heard of anything quite like it. As you said, there have been historical accounts of damage to rail lines (the 1896 Sherman tornado was noted to have caused incredible damage to rail lines, and the Tri-State tornado reportedly scoured away several hundred feet of trackbed and ripped up the overlying tracks somewhere between Gorham and Murphysboro), but nothing modern like this.

A large missile impact would definitely make sense, but that's not really what it looks like to me. On the other hand, it's hard to imagine that big a section of rail being displaced so far by the force of the wind alone. Especially when the trackbed isn't scoured out, which might have otherwise exposed it a bit more. My knowledge of rail lines is super limited so I don't really know enough one way or the other, but it's hard for me to wrap my head around. I'd be really curious to know what kind of force it'd actually take to accomplish something like that.

Pretty obvious there were some seriously violent winds there, though. The vegetation damage in that immediate area was really intense as well.
 

locomusic01

Member
Messages
84
Location
Pennsylvania
I forgot to post this earlier. While I was researching some other stuff, I dug up the paper on tree damage in Joplin and Tuscaloosa I vaguely remembered seeing a while back. You can read the full thing here, but the bit that's relevant to this thread regards Tuscaloosa:

Nevertheless, the best-fit vortex is shown with Rmax = 200 m (estimated from aerial photography), Vtan = 36 m s−1, Vr = 76 m s−1, and peak winds near 99 m s−1. The results suggest that the tornado was of EF5 intensity during this stage of its life, despite the EF4 rating assigned by the NWS. The EF4 rating may be attributable to a lack of EF-scale damage indicators in this section of the track, as shown in Fig. 3c. Of interest is that the tornado destroyed a railroad bridge during this period, as noted in Fig. 3c, implying very high wind speeds, but this indicator could not be used in the NWS assessment (K. Laws, NWS Birmingham, 2012, personal communication). Again, strong radial near-surface winds were needed to produce the best-fit tree-fall pattern.
The idea that Tuscaloosa may have reached EF5 intensity at some point is hardly news, obviously, but I thought it was noteworthy that the area of probable EF5 intensity using this method more or less coincides with the prevailing opinion. This area includes, among other things, the steel train trestle over Hurricane Creek Canyon and the coalyard where coal cars were thrown up to ~400 feet. This approach of using treefall patterns as a proxy for intensity seems to be pretty sound, so it's worth consideration I think. The study also suggests that max intensity coincided with clear RFD internal surges, which has been documented in several other tornadoes and is backed up in this case by both treefall damage patterns and radar data.

The structural damage nearest this area was already borderline EF4-5, and there are multiple lines of evidence that suggest it further intensified from there, so at this point I feel pretty comfortable mentally classifying Tuscaloosa as an EF5.

Also, just for convenience, note that 99 m/s is ~222 mph. The max wind speed estimate for Joplin in this study was 104 m/s, which is ~233 mph.
 

locomusic01

Member
Messages
84
Location
Pennsylvania
So I'm not sure how I missed this when it came out - or maybe I didn't and I've just forgotten? I dunno - anyway, Tim Marshall was on WeatherBrains last year and offered a lot more info on the ongoing EF-scale reevaluation process.


If the video doesn't jump to the right time, it starts around 1:10:46.

I also saw a presentation by Jim LaDue somewhere but can't find it right now. He also gave an overview of the process and everything they intend to cover. I've also reviewed some of the papers that've come out on the topic. Anyhow, I'd really recommend watching Tim's section of the video (and checking the other stuff if you can find it, or if I can track it down again and edit in links later), but the summary is that it sounds like they're hitting on pretty much everything many of us have brought up over the years.

Maybe most notably, there are proposals for utilizing direct measurements (mobile radar, mesonet, etc) in ratings in some form or another. They may be used as a basis for ratings or they may be added as sort of a secondary rating when the info's available (e.g. El Reno 2013 might have been given an EF-3-5 rating or somesuch, indicating an EF3 damage-derived rating and an EF5 wind speed). I still prefer the former, personally, but the latter would at least be progress. Either way, they're also working on developing standards for what sorts of measurements are usable, how to handle different measurement heights, etc.

They're also in the process of adding a bunch of new DIs (yay!), changing or eliminating some existing ones, reevaluating the DODs and so on. Some of the specific ones I've seen mentioned are jersey barriers (think Mayflower/Vilonia), grain bins, center-pivot irrigation systems, parking stops (think Joplin) and expanding the types of manufactured homes. They're also working to develop very specific guidance for assessing each DI/DOD and working on improving training so that there's better consistency between WFOs.

Marshall and others have also mentioned that they're taking the vegetation stuff completely out of the engineering side of things and turning it over to arborists and other experts who have more relevant experience. I know there's been talk of trying to create a more comprehensive set of "natural" DIs, so to speak, including different types of vegetation. I'd imagine the hangup there will be coming up with something that accounts for the huge number of variables that might influence vegetation damage without having to run extensive tests for each survey, which would obviously be very impractical. If it can be figured out, that'd be really big. It appears they're also considering ways to incorporate treefall pattern data like I mentioned above, which is pretty exciting. It's a really fascinating approach, and if it's actually as useful as it appears, it'd also be a huge help for rural tornadoes.

Oh, and they're also pushing for all surveys to be done through the Damage Assessment Toolkit, which would be awesome for us. All in all, it sounds like we should be seeing a much-improved EF-scale once this process is finished. Marshall and LaDue have both mentioned 2020 as a tentative timeframe, though of course it then depends on how quickly the recommendations are adopted once released.
 
Messages
387
Location
Niagara Falls, Ontario
I think this is good news. The point of the EF scale should be "how strong was this tornado to the best of our knowledge", nothing more and nothing less. While we don't want to see a return to the 1950s-1970s style of massively overrating some tornadoes (e.g. Tanner II on 4/3/74), I definitely think more DIs should be incorporated into the scale.
 

locomusic01

Member
Messages
84
Location
Pennsylvania
Yeah, I think any and all credible data should be considered. The ultimate goal is to better understand climatology and get a more accurate picture of when and where tornadoes happen and how intense they are. As it currently is, the EF-scale probably tells us more about population density and construction practices than maximum tornado intensity. It'll always be a tough thing to navigate, but I don't know that there's much of a downside to using all possible tools at our disposal (provided they're quality-controlled and reflective of near-surface tornado intensity).
 
Messages
74
Location
Lenexa, KS
Yeah, I think any and all credible data should be considered. The ultimate goal is to better understand climatology and get a more accurate picture of when and where tornadoes happen and how intense they are. As it currently is, the EF-scale probably tells us more about population density and construction practices than maximum tornado intensity. It'll always be a tough thing to navigate, but I don't know that there's much of a downside to using all possible tools at our disposal (provided they're quality-controlled and reflective of near-surface tornado intensity).
That is a nice way of putting it.
 

Peter Griffin

Member
Messages
16
Location
Newport, NC
Figured I would just give my opinion on the Chapman tornado and the damage it did to the railroads. I remember seeing the pics of the tracks and thought that it had to be mostly from debris impact. One of the bends in the track was just too sharp it didn't appear that it could be done by wind alone. I think debris impacted it at this point (possibly others) and resulted in the bending and shifting of the track. I'll see if I can dig up the pic later and point out what I am talking about. There is not doubting the Chapman tornado was violent but I don't think wind alone is responsible for the track damage. I'm no engineer though lol.
 
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