Significant Tornado Events

[Robinson lee]

I've seen you state this a couple of times. Do you actually have any studies showing so?

1968 Charles City IA F5 tornado once had a similar spiral scouring. According to the spiral scouring, some scientists speculated that the wind speed of tornado reached 528 mph. The fact is that the tornado in Charles City, as F5, has no very impressive damage. There is a relationship between the scouring and the movement and shape of tornado, as well as the soil, vegetation and water characteristics of the soil. Some very weak tornadoes have the same obvious effect In fact, spiral scour like this is not uncommon, such as Washington IL on November 17, 2013, Delmont SD on May 12, 2015 and Greentown tornado on April 11, 1965

 

[Casuarina Head]

It does appear that the Guin tornado produced extremely intense ground scouring within a narrow swath while moving at 70+ knots.

Scouring indicated by dark streaks at at top right, with a bare foundation (partly removed?) at the end of a driveway immediately to the left of the streaks:

Dark splotches indicate likely intense scouring at top left, near the centre of the narrow but intense swath of extreme destruction:

This image from Guin definitely seems to show not only extremely intense ground scouring in the foreground, but also some evidence of debris granulation:

The following image seemingly further confirms the existence of intense ground scouring along the entire path through Guin (compare with images one and two to verify locations):

Bankhead National Forest after the Guin tornado: note the intense band of inflow indicating near-total felling and possible (likely?) debarking of trees just right of top centre, very similar to the tree damage near the funeral home in Smithville.

Comparison with Smithville damage near the funeral home, seen at right-centre:

A closer view of the Smithville damage for comparison with the Bankhead impacts:

The more I read, the more I think Guin may deserve its upper-tier status, given the extremely short duration and narrow streak of intense winds.

 

[A Guy]

I could probably if I dug around, but it’s more just kind of common knowledge in the current era of tornado damage surveying, and have known NWS met professionals to discount it entirely in recent decades. I trust their word over dated methods of analysis. Spiral marking analysis was simply dropped entirely since implementation of the EF scale, and may have ceased even earlier than that.

That’s because as another mentioned earlier, it’s now known that even EF0-EF1 tornadoes produce dramatic cycloidal marks in open fields as long as there are suction vortices and loose vegetation that can be strewn in a spiral. All these markings are really indicative of is a multiple-vortex structure, which even weak tornadoes frequently exhibit.

There are specific events that show this lack of correlation too. A good example is Charles City. There was a newspaper article published at the time showing how spiral marking analysis was used to conclude some ludicrous wind speed estimate for the Charles City, IA F5 of 1968. I forget the exact number, but I think they placed it over 400-500 MPH, which isn’t thought to even be possible in tornadoes. Also, the damage it produced wouldn’t even be rated EF5 today, so whatever math they were using, was clearly flawed. Also of note, the Parkersburg, IA EF5 produced insane cycloidal scouring, but it was most intense near the end of the path, where structural damage had lessened to EF2-EF3. The very intense markings occurred just because there was more loose corn stubble to blow around in this area.

Fujita's method described in his Palm Sunday paper and the Charles City estimates are quite different. Lameroux and Waite used Van Tassel's method for the Scottsbluff NE tornado in '55, which yielded a similarly ludicrous 484 mph. It assumes the marks are elliptical - which of course they're not. Fujita's use of the correct cycloidal geometry gives estimates for the Greentown tornado that are fairly consistent with the EF scale windspeed for its damage intensity, or perhaps even slightly on the low side (average 174 mph, max 180 in that location).

I'm not prepared to dismiss it as readily as you, and characterising it as 'pseudoscience' is egregious. It's based on the predictable geometric variation of an ideal cycloid depending on relationship between the speed of the centre and rotational speed of the point producing it. Provided that his maths on cycloids is correct it's a sound foundation. It's other assumptions that are the issue (biggest is probably the transience of the windspeed). I'm not aware of any other literature recently testing this method, and Fujita himself didn't use it much. The conditions needed for such markings are readily obvious (clear multi-vortex structure, loose material on surface), intensity is not so relevant so that weak tornadoes have produced them is irrelevant (Edit: and posting pictures as if they prove some point equally so). The question would be is the speed expected from the geometry of the marks similar to that expected for damage? I can't find any answers on that.

It's hardly the weirdest non standard measurement method I've seen used in earth sciences. Speaking of which, there are quite a few interesting papers hanging about exploring the use of tree fall patterns to estimate tornado windspeed. Now there's a minefield of assumptions. There's even a paper on Joplin comparing three of them.

Just because a method isn't used doesn't mean it's wrong. Photogrammetry is very accurate provided the distances and angles are accurate, yet I can't think of any prominent examples of it being used for windspeeds after Fujita (if you know any I'm all ears). With the abundance of high quality footage these days, some showing the very base of the tornado (in comparison to, say, the Parker City measurement which was taken well above the ground) there's a whole PhD's worth of research that could be done calculating the windspeed visually and in some cases comparing it to EF DI speeds.

 

[pohnpei]

Just another example of cycloidal marks along with EF0 damage on its path. I believe it was from May 27 2019 tornado outbreak.

 

[MNTornadoGuy]

I would like to ask that do you have information about Maysville PA and Comanche KS tornado 1860?

The Maysville PA tornado dug 2-ft deep trenches and swept away all 20 buildings in the village of Marysville. Trees were reduced to debarked stumps and stones were reportedly rolled considerable distances.

The Camanche IA tornado was apart of a large and intense tornado outbreak across the Mid-Mississippi Valley. After doing a Goessel-Hesston-style handoff this massive tornado moved SE devastating the countryside. Despite its high visibility, at least 28 people were killed in rural areas as entire farms and sometimes entire settlements literally vanished. Intense ground scouring occurred as grass was completely stripped from the ground and prairie sod was "wholly blown away," trees were completely debarked or shredded and large stones were reportedly moved considerable distances. Eventually, the tornado entered the town of Camanche where 41 people were killed instantly. Here large 3-story brick hotels were completely leveled, numerous homes were swept away, and "trunks, clothes, beds, carpets, furniture, and even stoves absolutely vanished." At least 148 people were killed during the tornado outbreak, 92 of them from the Camanche tornado alone.

 

[Casuarina Head]

This what my list of what was probably the most violent tornadoes in recorded history (not in order):
Smithville MS 2011
Jarrell TX 1997
Hackleburg AL 2011
Philadelphia MS 2011
Sherman TX 1896
Tri-State Tornado 1925
New Richmond WI 1899
Fergus Falls MN 1919
Rochester MN 1883
Pomeroy IA 1893
El Reno OK 2011
San Justo Argentina 1973
Bridge Creek OK 1999
Moore OK 2013
Parkersburg IA 2008
Jackson MS 1966
Woodward OK 1947
Aetna KS 1927
Andover KS 1991
Comanche KS 1860
Maysville PA 1860
Wheatland PA 1985
Guin AL 1974
Brandenburg KY 1974
Tanner AL 1974
Udall KS 1955
Beecher MI 1953

Based on these images, Hudsonville ‘56 almost certainly belongs on this list, given extreme debris granulation and ground scouring.

Upon further review, my revised “master list” of well-documented “top-tier” contenders will likely be updated to include some additional events, particularly Camanche IA 1860, Rochester MN 1883, Rocksprings TX and Aetna KS 1927, Charles City IA 1968, Guin AL 1974, and Hesston/Goessel KS 1990 (yes, I would include both members of this pair). I think Charles City is often underrated because its most intense damage occurred in rural areas and was not as widely photographed as the damage in Charles City itself. The collection of images from the Hesston/Goessel tornadoes suggests that, aerials aside, ground-based images show some significant debarking, scouring, and possibly granulation, comparable with other intense tornadoes mentioned here, so perhaps they deserve to be listed as well.

 

[MNTornadoGuy]

https://www.tornadotalk.com/rochester-mn-f5-tornado-august-21-1883/
Rochester was definitely an extremely violent tornado. Entire mature cornfields were swept away.

 

[Casuarina Head]

I think you're referring to this
View attachment 6182
View attachment 6183
Cycloidal Marks estimating wind techniques was usual in early years, I remember 1957 Dallas TX tornado was estimated around 280mph for its marks.
Here's an excellent example to prove your theory"whatever tornado strength could make cycloidal marks".The following pics are Cycloidal Marks from different tornadoes of different strength in 8/24/2016 tornado outbreak.
woodburn IN EF3
View attachment 6186
unknown EF2
View attachment 6187
unknown EF1
View attachment 6188
unknown EF0
View attachment 6190

For comparison, here is an informative blog entry on the Plainfield, IL, tornado of 28 August 1990.

Information concerning the Plainfield tornado begins at 14:40 during the presentation.

 

[TH2002]

Here's some previous postings on Hesston and Goessel, Hesston does appear to have partially scoured grass in some areas but that's about it. Some of the vehicle damage is pretty impressive but perhaps it's nothing an F4 couldn't have done? Not sure.

Significant Tornado Events

To me, this suggests that there ought to be better communication between the NWS and the local community during the process of surveying. I know people who have had their homes destroyed have bigger things to worry about than the EF rating of the tornado, but if people were aware of these...

talkweather.com

Significant Tornado Events

To me, this suggests that there ought to be better communication between the NWS and the local community during the process of surveying. I know people who have had their homes destroyed have bigger things to worry about than the EF rating of the tornado, but if people were aware of these...

talkweather.com

This link has a pretty comprehensive collection of damage photographs from the Hesston tornado. Also, there is a section labeled 'Stucky Photographs' that is the only comprehensive collection of Goessel damage photographs I've been able to come across.

The damage in Hesston is definitely noticeably more intense than Goessel so I would probably side with an F5 rating for Hesston and F4 for Goessel. As for the cement factory photo, was the factory of metal or steel-reinforced concrete construction?

 

[Marshal79344]

Ground scouring and cycloidal marks should not be used to rate tornadoes in my opinion, although it should be used as contextual damage. There are certain types of fields in different parts of the country that make cycloidal marks really easy to see, such as an Illinois corn stubble field. Several EF0-F0 Tornadoes have produced visible cycloidal marks in that type of field. Some other fields also show the path of intense vortices better than others.

For Example, here is an aerial view of the Parkersburg Tornado Track. You can see the visible cycloidal marks that the tornado left behind in a non-mature cornfield.



If you compare that type of cornfield to this thick crop field in Illinois in July, it's much easier for a tornado to leave a visible scar in this type of field. Fields like this rarely appear in Dixie Alley.



The term "ground scouring" also is confused a lot. When a tornado rips crops to bare soil as it passes through a field, leaving a "dark-colored mark" as seen below with the Sibley, Iowa EF4 on June 25, 2010, several people like to call it scouring. Once again, these fields are rarely seen in other parts of the country. I bet that had this same tornado moved through grass fields in Dixie Alley that there wouldn't be scouring. Scouring, in my opinion, should be defined as when a tornado rips part of the ground out, not when a tornado leaves a pronounced mark in a field without actually ripping the ground up.



"Scouring" from the Sibley, Iowa Tornado as viewed from satellite




However, these images from the ground along the Sibley Tornado's track reveal that it simply destroyed crops, it didn't rip any dirt from the ground. The "scouring" visible from the satellite data was just cycloidal marks through tall crop fields, which are very prone to having cycloidal marks produced in them.

You just have to be mindful that some farm fields are more prone to having cycloidal marks produced in them than others. Contextual damage should be used to get a better image of a tornado's intensity than just marks in a field. However, marks in a field should be used to justify that an event was indeed a tornado. This is commonly noted during damage surveys for weak tornadoes in the High Plains area.

 

[CheeselandSkies]

There's quite a bit of footage on YouTube of the Merrill tornado though that video seems to be the only one that catches the tornado forming. Is the previous outbreak you're talking about the one that spawned the Stoughton tornado?

Yes, that's the one.

 

[Juliett Bravo Kilo]

The damage in Hesston is definitely noticeably more intense than Goessel so I would probably side with an F5 rating for Hesston and F4 for Goessel. As for the cement factory photo, was the factory of metal or steel-reinforced concrete construction?

I'm not sure about the factory, I'd love to get a before and after photo set of it.

Another damage pic from Hesston. You can see home homes swept away near the bottom corner but that's about it. I'm not sure if this would warrant EF5 today though, looks like the F5 damage corridor was confined to a small area. Not sure if the cement factory was considered F4 or F5 by the damage survey team. I'll have to go through the library collection of damage photos some other time.



Wasn't sure where else to put this so I'll stick it here. A photo of the Goessel tornado crossing Kansas 15 southeast of the town.

Credit: Doug Nelson





The aforementioned library link:

1990 Hesston Tornado · Hesston Public Library

Digital collections of the Hesston Public Library in Hesston, Kansas, USA

hesston.digitalsckls.info

 

[Juliett Bravo Kilo]

It does appear that the Guin tornado produced extremely intense ground scouring within a narrow swath while moving at 70+ knots.

Scouring indicated by dark streaks at at top right, with a bare foundation (partly removed?) at the end of a driveway immediately to the left of the streaks:

Dark splotches indicate likely intense scouring at top left, near the centre of the narrow but intense swath of extreme destruction:

This image from Guin definitely seems to show not only extremely intense ground scouring in the foreground, but also some evidence of debris granulation:

The following image seemingly further confirms the existence of intense ground scouring along the entire path through Guin (compare with images one and two to verify locations):

Bankhead National Forest after the Guin tornado: note the intense band of inflow indicating near-total felling and possible (likely?) debarking of trees just right of top centre, very similar to the tree damage near the funeral home in Smithville.

Comparison with Smithville damage near the funeral home, seen at right-centre:

A closer view of the Smithville damage for comparison with the Bankhead impacts:

The more I read, the more I think Guin may deserve its upper-tier status, given the extremely short duration and narrow streak of intense winds.

Guin is something I'd love to have more clear photographs of the damage, as I've no doubt it was a violent tornado, but the sparsity of reliable documentation makes it hard to ascertain. That said, more and more photogaphs of its damage are being tracked down so I think in time we'll have a pretty clear picture of it.

 

[TH2002]

I'm not sure about the factory, I'd love to get a before and after photo set of it.

Another damage pic from Hesston. You can see home homes swept away near the bottom corner but that's about it. I'm not sure if this would warrant EF5 today though, looks like the F5 damage corridor was confined to a small area. Not sure if the cement factory was considered F4 or F5 by the damage survey team. I'll have to go through the library collection of damage photos some other time.

View attachment 6200

Wasn't sure where else to put this so I'll stick it here. A photo of the Goessel tornado crossing Kansas 15 southeast of the town.

Credit: Doug Nelson

View attachment 6201



The aforementioned library link:

1990 Hesston Tornado · Hesston Public Library

Digital collections of the Hesston Public Library in Hesston, Kansas, USA

hesston.digitalsckls.info

It's very possible that Hesston, much like the 2011 Tuscaloosa-Birmingham tornado, falls in an unusual place. F5 but not EF5. I don't know if any anchor-bolted homes were swept away and as you said I'm unsure about the construction quality of the factory that was struck. Some interesting verifiable occurrences with this tornado, however, per Grazulis: "Checks from a plumbing and heating supply store in Hesston were found 85 miles to the northeast in Manhattan, KS." and "A personal check was carried to 5 miles NE of Blaine, KS, 115 miles to the Northeast." I have to wonder about the nature of the damage to the plumbing supply store.

Video on YouTube of the damage in Hesston. I believe the factory can be seen at the end of the video (not 100% sure though) where a bystander mentions "concrete in the background", implying that the factory may have been of steel-reinforced concrete rather than metal construction. Again not 100% sure though. Still trying to find a more detailed description of the damage survey.

 

[Juliett Bravo Kilo]

It's very possible that Hesston, much like the 2011 Tuscaloosa-Birmingham tornado, falls in an unusual place. F5 but not EF5. I don't know if any anchor-bolted homes were swept away and as you said I'm unsure about the construction quality of the factory that was struck. Some interesting verifiable occurrences with this tornado, however, per Grazulis: "Checks from a plumbing and heating supply store in Hesston were found 85 miles to the northeast in Manhattan, KS." and "A personal check was carried to 5 miles NE of Blaine, KS, 115 miles to the Northeast." I have to wonder about the nature of the damage to the plumbing supply store.

Video on YouTube of the damage in Hesston. I believe the factory can be seen at the end of the video (not 100% sure though) where a bystander mentions "concrete in the background", implying that the factory may have been of steel-reinforced concrete rather than metal construction. Again not 100% sure though. Still trying to find a more detailed description of the damage survey.

Well it was a cement factory so it could have been concrete that was being manufactured inside the building, not from the building itself.

 

[buckeye05]

I would say that ground scouring can be a good indicator of extreme intensity, but only when a certain types of ground and surface vegetation are impacted. People get too excited over any type of mark that a tornado leaves on the ground. Scouring of farm fields is not particularly significant, as these fields have higher vegetation, and loose soil from tilling and plowing. It doesn’t take a very strong tornado to leave a distinct and visible path in these conditions. Now what IS impressive is what grass or very short surface vegetation, and topsoil is scoured from the ground, such as lawns in a residential area. That type of ground scouring is a phenomenon associated with only the most violent of tornadoes. Trench digging is another type of scouring that is very rare, and suggestive of remarkable strength.

Now this damage picture from Guin, AL 1974 is pretty much among the most textbook examples of what extreme, EF5 level ground scouring looks like close up. Notice the complete removal of surface vegetation, and scouring of the underlying topsoil in the foreground. What’s even more impressive is how scour-resistant Alabama soil is, and how fast-moving the Guin tornado was. Taking these factors into consideration, I’d say this photo shows the most impressive ground scouring I’ve seen in the state of Alabama.

 

[TH2002]

I would say that ground scouring can be a good indicator of extreme intensity, but only when a certain types of ground and surface vegetation are impacted. People get too excited over any type of mark that a tornado leaves on the ground. Scouring of farm fields is not particularly significant, as these fields have higher vegetation, and loose soil from tilling and plowing. It doesn’t take a very strong tornado to leave a distinct and visible path in these conditions. Now what IS impressive is what grass or very short surface vegetation, and topsoil is scoured from the ground, such as lawns in a residential area. That type of ground scouring is a phenomenon associated with only the most violent of tornadoes. Trench digging is another type of scouring that is very rare, and suggestive of remarkable strength.

Now this damage picture from Guin, AL 1974 is pretty much among the most textbook examples of what extreme, EF5 level ground scouring looks like close up. Notice the complete removal of surface vegetation, and scouring of the underlying topsoil in the foreground. What’s even more impressive is how scour-resistant Alabama soil is, and how fast-moving the Guin tornado was. Taking these factors into consideration, I’d say this photo shows the most impressive ground scouring I’ve seen in the state of Alabama.
View attachment 6202

Which tornado would you say was more violent, Guin AL 1974 or Smithville MS 2011? Or are they on a very comparable tier?

 

[buckeye05]

So this photo of Hesston shows the most intense area of house damage in town, and what was probably the main basis for the F5 rating. The problem is that all but two homes still have their wooden subflooring still attached to the basement foundations. Close up photos of the homes that DID have their subflooring ripped off (which I frustratingly can’t find right now), show evidence of poor construction and a distinct lack of anchor bolts in that small subdivision. That type of damage would be rated EF4 today.

Now with that said, I’d really like to know what that large building that is completely slabbed near the top of the photo was.

 

[buckeye05]

Which tornado would you say was more violent, Guin AL 1974 or Smithville MS 2011? Or are they on a very comparable tier?

I’d say Smithville by far. The Smithville tornado produced damage that was so intense, that its nearly incomprehensible. Now with that said, the Guin tornado was much more poorly documented, and the clearest damage photos have been lost to time. Some of the photos that armchair tornado damage sleuths have dug up do suggest an extremely violent event occurred in Guin.

 

[buckeye05]

It does appear that the Guin tornado produced extremely intense ground scouring within a narrow swath while moving at 70+ knots.

Scouring indicated by dark streaks at at top right, with a bare foundation (partly removed?) at the end of a driveway immediately to the left of the streaks:

The foundation removal debate in Guin is very tired, and pretty convincingly debunked at this point. That driveway almost certainly ends at a block foundation home that’s had it subflooring swept away and obliterated.

edit: toned it down, I’m frustrated